volcano monitoring

Possible eruption in Virunga National Park, Congo

eklemetti — Tue, 31 Aug 2010 06:29:04 +0000

Possible eruption in Virunga National Park, Congo

Busy ... so busy! I'll try to have more later today but the next 24 hours for me are super duper busy.

However, I did want to pass along some news that was noticed by the Volcanism Blog that a volcano at Virunga National Park in the Congo erupted overnight. Now, I haven't been able to find much information beyond the single report in the Irish Independent - and that report doesn't even specify what volcano is doing the erupting - Nyamuragira or Nyiragongo. However, we've seen eruptions at the park earlier this year so the volcanoes are almost constantly degassing, so this should be a surprise. However, until I can get more information, I'm calling this a "possible eruption."

More later on this, Sinabung, Etna and whatever other volcano decides to add to the week!

eklemetti Tue, 08/31/2010 - 02:29

Tags

Congo

New eruption

Nyamulagira

Nyamuragira

There are no large earthquakes in the area according to EMSC. That is earthquakes above Mb4.5 in size.

OT for current volcanoes, but interesting after-effects at FimmvÃ¶rduhÃ¡ls at
www.icelandreview.com/icelandreview/daily_news/?cat_id=75139&ew_0_a_id=…

Confirmed eruption at Nyamuragira Shield Volcano. Note that name is not used here either, but it darn well isn't the stratovolcano of Nyiragonga:) So logic gives...

Pictures in link, spectacular:
http://gorillacd.org/2010/01/02/massive-volcanic-eruption-in-the-nation…

Watch out Carl, that article you linked to is from the January 2010 eruption!

Mea culpa, just noticed... Recanting former statement.

Something tells me that this was a "duck".
It is weird that the Irish Independent breaks the news, especially since there was some rather spectacular photos from Nyiragongo released yesterday with soldiers photographed looking down into the lava lake. Photos where dated august 30 2010.
I guess an overexcited editor in Ireland thought that was an eruption after cuaffing a few Guinness.

There is a thermal anomaly at Nyiragongo on Modis Thermal Alerts , date 08/30/2010
http://modis.higp.hawaii.edu/cgi-bin/modis/modisnew.cgi

Etna shows a slow but continous rising of tremors: What does that mean? http://www.ct.ingv.it/index.php?option=com_wrapper&view=wrapper&Itemid=…â©=en

@Thomas Wipf

I suppose it means that the wavy harmonic line ( *buzz* ) on the seismometer plot is getting thicker. Not easy to tell however

http://i34.tinypic.com/69j583.jpg

@Thomas Wipf & Raving: The current increase in volcanic tremor amplitude at Etna could mean that the central conduit system is pressurizing (which has been pretty evident over the past few days); at the same time there have been no further ash emissions (caused by explosions or crater wall collapse) from the Bocca Nuova since the morning of 30 August. It is not excluded that one or more large, vent-clearing phreatomagmatic explosions will occur anytime soon, and for this reason access to the summit craters of Etna is prohibited since 27 August. We had the first such explosion on 25 August, but the Bocca Nuova continues to be obstructed.

At the same time, the conduit of the Northeast Crater on the other side of Etna's summit area is open and has been the site of deep, loud explosions since several months, and it is well possible that magma is gradually rising in this conduit.

I guess we will better understand what is going on quite soon ...

Mildly OT, Jessica Ball at magmacumlaude is running a series of blogs on her fieldtrip to Montserrat this summer. Wow.

http://magmacumlaude.blogspot.com/

I have been away from posting for a while and I am way behind in reading so I think I will start back here. I may get to some of the other threads later, but right now, I just want to get back in.

Looks like some interesting things going on with a volcano that the authorities thought was extinct? Hmmm. I have my own theory on that and I know some here would disagree with me, but I don't believe any volcano is truely extinct. There is a college right in the middle of a crater called Howell Mt. in N CA and not too far from that crater is a geyser that they call the "Old Faithful" of CA. It is not that predictable, but it does go off frequently and you can get rather close to it: as within about 30' or less. You can also get right up to it and there are fish living in the water by the blow hole.

I don't know much about this, but I do know that Mt St. Helena is near Howell. The former is not extinct. So I have a question for those of you who are more knowledgeable than I am to explain what constitutes an extinct volcano. I know there are geologic reasons that can show that some volcanoes are extinct, such as the cones on the flank of Etna that erupt once and that is it for them. Or is it? What would stop them from erupting a 1000yrs down the line?

Just wondering. I have my reasons for believing that no volcano is truely extinct and it is just based on theory and speculation, not what is seen, the geology of the area around the volcanoes, plate techtonics, and whatever else is going on deep below the crust, which would indicate that a volcano is extinct.

Any thoughts?

@Diane N CA [12]

Dunno... this one under Jackson Mississippi might safely be assumed to be extinct.

http://i52.tinypic.com/5e5mya.jpg

@11parclair, great link - those observatory videos are something, thanks.

Diane: I think time scales have something to do with it. Southern Finland was full of very active volcanoes over 1,5 billion years ago. None of them has erupted during the last 1,5 billion years. I guess those can be considered extinct?

The Indonesian authorities never claimed that Sinabung was extinct.

Volcanoes are described as active, dormant, or extinct. These are relative, descriptive terms.

Active Volcano: A volcano that is erupting. Also, a volcano that is not presently erupting, but that has erupted within historical time and is considered likely to do so in the future.

Dormant Volcano: Literally, "sleeping." The term is used to describe a volcano which is presently inactive but which may erupt again. Most of the major Cascade volcanoes are believed to be dormant rather than extinct.

Extinct Volcano: A volcano that is not presently erupting and is not likely to do so for a very long time in the future.

Mt Sinabung has shown anecdotal evidence of being weakly active in the late 19th and early 20th centuries, but *relative* to the many active volcanoes in Sumatra, it was given a classification by government geologists, as 'known active in the past, presently inactive' (B group).

The Indonesian government had to prioritize monitoring centers for earthquake, tsunami and volcanic hazards because resources are spread thinly, as the island arcs (several) sit on an exceptionally geologically active region.

Relative volcanic risk, for Indonesia, means that volcanoes that were not active in the past 100 years are probably not going to be very active in near future. When you must pick and choose between critical monitoring needs with limited resources, decisions on where to site equipment and assign manpower must be made on the best available information.

@Lurking #13, thanks. I had no idea there was a volcano under Jackson Miss. That is a great map of the volcano, too.

@Passerby, I figured you would give me a good answer to my inquiry. Thanks for clarifying some terms for me. I got the idea the Indonisian gov. figured it was extinct because, if I remember right, someone else thought they did. I can see why they have to pick and choose. There is so much going on over there they probably can't really keep up with all the activity.

@Jack #15, I forgot about Finland's volcanoes. It has been mentioned before so I should have remembered. :-) Anyway, I suppose they could be considered extinct.

Does anyone have any idea when the last time the Sutter Buttes in the Northern Central Valley of CA erupted? I know someone mentioned it before, but it was quite a while ago so I don't remember. (note to self: write it down!)

Hi,

@ Diane, #12: Another possibility might be the "hot spot one": a plate moves over a hot spot, creating a chain of volcanic islands. Any volcanic island that is far enough removed from the hot spot through plate tectonics might safely be considered as extinct, I guess (what ever "far enough" is).

Diane,

Here is a link to the the USGS and a bit of into on Sutter Buttes.
http://tapestry.usgs.gov/features/33sutter.html
Doug Merson

@Diane [17] -
Our volcanoes can indeed be considered extinct - nothing visible remains of them, only the pipes & diamonds...

Diane,

to go with CK's comment, Midway is a "hawaiian" volcano, it is extinct. I believe that Diamond head on Oahu is considered extinct. The big island has several (3-5) active volcanoes and Maui has 1-2 active/dormant volcanos. However all of them, including Midway 1000 miles away are the same hotspot.

OT, but just out of curiosity.

Mag 2.7 Date-Time: Tue, August 31, 2010 at 18:00:30 UTC

Location41.781Â°N, 87.850Â°W
Depth0 km (~0 mile) set by location program
RegionILLINOIS 20 km (10 miles) WSW of Chicago, Illinois

Mag 2.7 comes up at about 11.2 Tons TNT (â707 MJ). That lat and lon do pop up in a quarry, Vulcan McCook Quarry.

Isn't that a little large for a quarry less than a mile from a residential area?

I am seeing interesting change in the tremor plots around EyjafjallajÃ¶kull. The eruption has not resumed at this point. But this change in tremor plots is interesting and does not seem to be related to weather changes. Sometimes the tremor plot change before something happens. But only time is going to tell is if that is the case now in EyjafjallajÃ¶kull or not.

The change can be seen on station esk (Eystri SkÃ³gar), mid (MiÃ°mÃ¶rk) so far.

@JÃ³n FrÃmann

The other day I was trying to relate what the difference in "tremor" and "quake" to my wife. I used an analogy of being able to hear water running in a pipe, as the fluid moves through it. But magma and hydrothermal fluid being much much lower in frequency.

Was my analogy correct?

If so, does the climb in the low frequency tremor level denote a deeper location for this movement?

@Lurking, This is like water under pressure, a lot of pressure. When it gets released from that pressure, it boils and sometimes explodes like we sometimes see. Your analogy is good enough to explain magma. But this is far more complex that in my opinion. But you should ask the real experts here on this question, like Erik or Boris.

This did happen in EyjafjallajÃ¶kull at the start of the eruption. But when water got stuck under the glacier in the first few hours there where massive spikes in the harmonic tremor plots on the low frequency, that is 0.5 - 1Hz.

@22, Lurking, that is a functioning quarry and a recycling center, near Midway Airport (you can see it on the Waymarking map by zooming in at the next link), according to this site: http://www.vmcmccook.com/

It's been running for 100 years and covers 650 acres. Maybe they do blasting? If so, there should have been many other quake-type episodes, but I've never noticed any. Quakes are more often on the Mississippi River by Missouri and Arkansas. http://www.waymarking.com/waymarks/WM501Q_McCook_Quarry_Vulcan_Material…

@Jane...

It wasn't really a question of it being a quarry... just in the calculated size of the blast.

It generated a Mag 2.7 seismic event. At the equivalent of about 11.2 Tons of TNT, that's about the size one would expect of a Western State open pit mine in a cast shot with ANFO. Not in a neighborhood quarry mining building material. Sure, they have issues with the State over compensations for Joliet Rd starting to slip off of what is left of the ground it is precariously perched on, but 11.2 tons equiv of TNT in one blast? Think autos... that is the same as about seven pickup trucks packed to the gills with explosives.

In 1899, a fire at Ft Pickens set off 8000 lbs of black powder (a much weaker explosive) and hurled bricks across the bay to Ft Barrancas when the powder mag was destroyed. That's about 1.5 miles.

Thanks for all the answers. I appreciate it. I did not know that the Sutter Buttes were considered to be the southern most outcrop of the Cascades. I always thought it was Lassen. When I took geology, the teachers told us that no one at that time knew why there was a volcanic eruption right in the middle of the northern part of the Central Valley. Maybe they know more about it now. It is sort of a strange place for a volcano to come up.

Thanks, Doug Merson for that link.

Kultsi, what part of Finland are the pipes and whatever else is left of the volcanoes there? I do remember you telling us, but lately my brain has been discombobulated. LOL. Anyway, thanks for letting me know what is left there to see. Do you have any links to a picture of them?

Did the USGS have it listed on their map as a possible quarry blast when you posted your first comment, Lurking?

It is now.

Difference in seismic wave patterns, volcanic and tectonic:

www.vulkaner.no/v/vulkinfo/ordbok/vulktrem-e.html

Show that to your wife. The wave form is quite different, as you can see. She's not that fluffy, or you wouldn't have married her.

@Diane N CA, You can see all the known volcanoes here (link below) in the U.S.

www.volcano.si.edu/world/region.cfm?rnum=12

@Passerby

Yup... listed as a possible quarry blast, pulled up Google Earth and zoomed in, "epicenter" slap dab in the middle of a quarry. Used street view to find out the name of it, found out that they are having 'issin contest with the state over the road that has been closed since either side has been mined down to roughly a 70 to 100 foot drop on either side and it's now starting slide off of it's perch.

The wife doesn't follow this like I do, but occasionally she finds amusement and interest as I leap around the house ranting about seismic activity.

Eh.. it's a hobby. At least I haven't scared the dog lately.

Maybe the removed the damaged road bed; it's a safety hazard.

@29
>Difference in seismic wave patterns, volcanic and tectonic:

That USGS image is very misleading as it's got a very uncompressed waveform scale (240 pixels/10 seconds) compared to most helicorder views that can be seen on the web. This is what is becomes after it becomes comparable in scale (about 12 pixels/10 seconds):

http://img830.imageshack.us/img830/8194/6mbapz99.png

Very little detail can be understood from such compressed yet widely used scale.

QuakeExplorer allows you to zoom in on an event... provided you can wrangle the right miniseed into it. (that is, if you can find it to begin with)

http://alomax.free.fr/QuakeExplorer/

I'm still trying to figure it out, and am looking for something with a more idiot proof interface.

I was able to pull off an interesting trick with it though, I was able to pipe the waveform out as a .wav formated file, drag it into Dplot and run FFT's on the data. Sure, QuakeExplorer offers a frequency component display, but doing it via Dplot allows me to compare time segments (obtained via different set ups for the seed link) overlaid on each other.

Quite handy if I can figure out what I'm looking at.

I don't know, if this has already been posted by somebody else, but the WorldNews website has a short article about the Sinabung eruption with a pretty cool picture:

http://www.newstime.co.za/WorldNews/Indonesias_Sinabung_erupts_red_aler…

Actually, I hope the picture is in fact from Sinabung and not some other eruption....

Last report of ChaitÃ©n. Note that is the 2nd time that has an increased level in a short lapse of time (see the previous report). Meaning something? I think not, but you never know.

It's nice to see that Volcanism Blog has returned to life after a long ausence.

http://www2.sernageomin.cl/ovdas/ovdas7/informativos2/Regiones/2010/RAV…

Posted this on the other thread--

Jakart Post (their) Weds. am update on the situation around Sinabung

www.thejakartapost.com/news/2010/09/01/sinabung-smolders-while-fear-gri…

#28 Best word of the year: "discombobulated". That's the way I feel when I come back from a hard day's work and read so many new posts. Thanks, Diane, for making me laugh. I needed it!

Today's word is suspense. ... :-|

http://i56.tinypic.com/157oqk5.jpg

I'm still feeling a little verklempt after reading the last few posts in the previous thread. :(

I seriously regret having asked about the underground bunkers that poster "Val" mentioned.

I understand that there are certain types of people in this world who believe it's OK to create a profit-making venture out of other people's death and misery, but I'll always consider it disgusting and disrespectful.

#40 No verklempt feelings,YRH - you have a great heart.

#35. I wouldn't be surprised if that picture comes from Mt Merapi?
http://grdurand.com/blogger/uploaded_images/merapi_lava-752853.jpg
And: http://www.theage.com.au/articles/2006/05/13/1146940775320.html

And oh, thanks Eric for a wonderful site! ;)

Umm.... that's a lot of stations.

For anyone with a proclivity for the technical side of seismology...

The IRIS network list:

www.iris.edu/mda

and the IRIS BUD (Basic Uniform Data) link:

www.iris.edu/bud_stuff/bud/bud_start.pl

Best I can find is that one station that I mentioned earlier at Toba, however there are quite a few Malaysian stations that would likely pick up the larger events in Indonesia.

*sigh... back to square one.

#42. Oops, sorry about the first link. This will work better:
http://grdurand.com/blogger/2006/06/largest-burst-yet.html

#35 & #42. Now I (we?) don't have to wonder anymore:
http://www.life.com/image/71174715

Just hate when journalists does that. >:(

#40 I very much agree. I went to the village of Kaliadem (where the fateful bunker is located) for the magnificent view of Merapi from there. What was shocking on my arrival was that only a year after the tragedy, literally dozens of stalls were set up near the bunker selling "souvenirs" from the pyroclastic flow location, including video of the digging/rescue operation! And the only reason the two victims were there in the first place was to help save the local population...

The bunker in Kaliadem is a very sad example of an otherwise great idea gone wrong. If that door had shut properly, the bunker would likely have saved the lives of two people who would have had no other way of escaping the pyroclastic flow on time. Another feature in areas close to and south of Merapi are pyroclastic flow dams, including one in Kaliadem that may have slowed down some of the PFs in 2006 and helped protect some of the areas further downslope.

#41 Renato, some people never know the comfort their kindness brings to others.

I remember spending so many wonderful hours laughing and learning with all of you while watching the sun set and rise over EyjafjallajÃ¶kull after my twin sister passed away suddenly in March.

Renato, you and many others here have such great hearts. I'm forever grateful.

#47 Princess: If you start talking like this, I'll get "discombobulated" again.
Love you guys!
Take a look at Parclair's YouTube video on "Empathy" over the other thread ("A request by me"). You will surely find some comfort from it.
In the meanwhile, we have a lot of work trying to cope with these two ongoing eruptions.
Always missing you around. Would like to hear from your Haitian protÃ©gÃ©.
PS: I still watch the sunrise and set at Eyjaf.

#48 Right now there are flocks of birds hovering frÃ¡ new Ãorvaldseyri cam (the only one working besides MÃºlakot)
And I must hit the bed. Good night!
OT: Missed a post from you over the "A request from me " thread.
You should show your whole cold blooded genealogical three dating back from the Tudors. Promise I'll keep paparazzi away.

#49 *typo* genealogical tree

Does somebody have an interest in Nyatambe hill in Gwassi at the shore of Lake Victoria, Kenya. It has a very deep crater at the top and many volcanic rocks around it which the locals call 'kamasia'. I nver read about it in Geography and with the settlements around it, I am worried that if it is not extinct, then there is a disaster waiting to happen.

Thank you Renato. I'm watching the video right now (thank you Parclair!), but have paused it to say: the boy I sent to high school in Haiti has chosen to stay working in carpentry but his younger sister will be taking his place at the school, so it's all good. :)

#51 Please, Lehman Leo, tell Nyatambe to give us some time 'till we get our feet on the ground over these too already in motion. ;)

#52 Thanks to your spontaneous act of empathy. Be good!

Lava at the crater?
http://cdn.wn.com/ph/img/86/dc/767fde443cde2d1c9a58d438e808-grande.jpg

I think the report came from this.

http://english.peopledaily.com.cn/90001/90783/91321/7122742.html

#49 Renato the fra-hvolsvelli cam is showing a beautiful sunrise (but I know what you mean - the cams are hit-and-miss these days)

May I post on the "A request from me " thread tomorrow Sir Renato? I've had three careers to date, my resume is outdated, it's 4 a.m. and I'm exhausted and discombobulated all at the same time.

Oooh! Did you hear there's a new season of The Tudors on CBC this fall? No need to keep the paparazzi away. I'm just an illegitimate corn chip offspring trying to keep a low profile (see paragraph #2) :)

#57 Till tomorrow then. I'm already falling apart. TschÃ¼ss!

#51 Lehman Leo - Isn't Nyatambe Hill just ... a hill?

@Renato Rio #55, that photo shows the active lava dome of Kelut (or Kelud) which grew during the winter 2007-2008. Similar and extremely spectacular photographs of that lava dome are at Volcano Discovery: www.volcanodiscovery.com/en/kelud/1107/lava_dome.html

@Princess Frito #59, if you knew how many rather peaceful-looking hills are actually volcanoes ^-^

ETNA UPDATE - a summary on Etna's activity during the month of August 2010 is available at the INGV-Catania web site:

Italian - www.ct.ingv.it/index.php?option=com_content&view=article&id=240

English - http://www.ct.ingv.it/index.php?option=com_content&view=article&id=243

@Boris Behncke (#60) Glad to see you chipper this morning

Might be a typo in your report?

"... The explosive evento f 15 August was accompanied ..."

@all:

Regarding Virunga National Park eruption...
Seems like some editors brain ran a bit to far with some newly released photographs taken on 30 august 2010 showing soldiers trecking around on Nyiragongo with the lovely lava lake in the background. For a layman journalist it is quite understandable that they think that it is an eruption.
But on the other hand, what is an eruption after all, lava flowing around happily in a lake could in some sense of the word be considered as an eruption.

Here is a link of some of the photographs, there are more on Xinhua/Reuters if you have access to their archives.
http://www.cam111.com/photonews/2010/08/30/44656.html

@Raving #61, thanks for pointing out that (double) error - also the date was wrong (25 August, not 15 August). You made my day!

Wow, the tremors at Mount Etna are rising more and more. http://www.ct.ingv.it/index.php?option=com_wrapper&view=wrapper&Itemid=… On this webcam one can see a lot aof degasing going on today: http://www.guide-etna.com/webcam/
@Boris Behncke My parents will go to Mount Etna End of Septmeber. How is the situation right now? Any summit-tours allowed right now?

@Thomas Wipf #64, the summit craters are currently off-limits - access is forbidden due to the fact that the conduits of the Bocca Nuova, Voragine and Southeast Crater are obstructed and the gradually increasing tremor amplitude might be a sign of rising gas pressure, which could be released with a large phreatic or phreatomagmatic explosion.

I have been an avid lurker of this forum for some time. Felt I should say that the reason the Irish Indo was the 1st paper to publish this story(I believe) is because the Irish Army is in the Congo as peacekeepers.
The Irish Army has been there for many decades and as a result there are strong links between the Irish and the Congolese.

The role of the Ãglaigh na h-Eireann there goes beyond Peacekeeping. They provide alot of humanitarian and rescue work. The would know the lay of the landscape pretty well.

@Diane [28] -

The pipes are mostly on the Eastern side of Finland, tens of kimberlite pipes have been fond this far. This is old crust area; the aging of the pipes is between 590 to 625 Ma. Not all pipes contain diamonds, and the prospecting is very expensive, as the pipes are often covered with glacial moraines several tens of meters thick.

No indication of the ancient volcanoes remain visible: we had this great grinder at work during the last ice age; also kimberlite is quite suspect to erosion, so it is not easy to find.

Picking up a diamond on the ground here is possible, but the most likely reason for that is that somebody dropped it...

How'd y'all get that photo to work with your comment? I need one! :)

This sounds decent. We are resting here in my own hotel room in Killarney checking a lot of these comments. Several are good while some do not help to make a lot of common sense at all. I'm just on vacation however I could not help myself from looking around this blog although my hotel room right here in Killarney charges on line usage per hour.5 star hotels killarney kerry,5 star hotels killarney special offers

Nyatambe is just a hill right at the shore of lake Victoria in Gwassi, Kenya but with a deep crator at the top. Local legend has it that if you fall into the crater, the only place to discover your daed body is in Lake Victoria.

You can come and see for yourself by visiting Gwassi.

My mate and I had been just discussing this specific subject, she is normally looking for to prove me totally! I am about to show her this post and additionally rub it in a bit!

Sinabung and Etna updates for 8/30/2010

eklemetti — Mon, 30 Aug 2010 06:20:09 +0000

Sinabung and Etna updates for 8/30/2010

Classes starting today, so I have to be brief:

Unique twin ash plumes from Sinabung in Indonesia, erupting on August 29, 2010.

Sinabung
The Indonesian volcano continues to experience explosions, which one last night (well, last night here in Ohio) that prompted an ash advisory for aircraft up to 6,100 m / 20,000 feet, although most reports I've seen pegged the ash column at closer to 2,000 m / ~6,500 feet. Eruptions readers have found a bevy of links for footage and information about the eruption, including a remarkable image gallery from the BBC that shows the volcano exhibiting two ash plumes - one that is vertical, one that is shooting off to one side (see above). This definitely makes it seem that the vent is partially blocked and these explosions are helping "clear the throat" of the volcano (NOTE: this does NOT mean I think something big is going to happen, rather just that it seems to be the reasonable explanation for the bifurcation of the plume). My hunch is that even now, very little "new" juvenile magma has been erupted from Sinabung, but that is pure speculation until there are any analyses of the ash shard morphology or composition.

There is also some video from Portuguese television Some of the most recent images from the volcano show a strong, single plume with some rock avalanches (possible block and ash flows) on the flanks. Evacuations have increased to over 21,000 people living near the volcano and some flights have been diverted due to the taller ash plume. The biggest threat right now is the ash fall from the explosions and as such, the government is providing face masks and moving people to sturdier shelter. The current death toll appears to be 8 (video), mostly from respiratory-related problems. What comes next might be a guess for everyone at this point as the Surono, head of the Indonesian Center for Volcanology and Geological Disaster Mitigation admitted again "We don't know what set it off, how long it will continue or whether to expect pyroclastic flows or more powerful eruptions."

Etna
Not to be forgotten, Etna continues to show signs that it is entering a new cycle of eruptive activity as well (albeit much less of a surprise than Sinabung). Dr. Boris Behncke points us to some new updates from the INGV (italian - top and english - bottom) that describe the explosions and collapses that have been producing the ash fall on Sicily. Be sure to check out Dr. Behncke's Photostream for the latest and greatest images of the current activity at Etna - currently he has some close ups of the explosions occurring in the Bocca Nuova crater (not to be missed). You can always watch Etna's show on the multitude of webcams as well.

eklemetti Mon, 08/30/2010 - 02:20

Tags

Just a little correction - the updates at the INGV web site are now both in Italian AND in English (I am personally taking care of that!), though the titles remain in Italian so far.

For another list of Etna web cams, compiled by my friends of the Hotel Corsaro, look here:
www.hotelcorsaro.it/etna-webcams/?lan=english
I also hope we will soon have the images of the new Montagnola (upper south flank of Etna) web cams, both visible light and thermal, on-line on the public pages of the INGV.

As for Sinabung, unfortunately there seems to be very little instrumental monitoring at this volcano, and thus it is extremely difficult to say what will happen there. Go figure, it's often difficult even to forecast the behavior of a volcano that is extremely well monitored! All depends on the signs that a volcano gives, and how they fit with previous records. At Sinabung there is little of the two, poor instrumental monitoring, and no data for comparison. I hope the volcanologists there will soon have the possibility to install more monitoring equipment - at Pinatubo in 1991, such action helped to save tens of thousands of lives.

Thanks for correction, Boris. I thought you said that but then the page said "There are no translations available" so I was a little confused. Maybe I should have just, you know, read the english (funny how the brain works on no coffee).

@Erik, ah yes the coffee factor ... I am lost without having had my morning coffee, especially under the climatic conditions in Sicily; let's hope Etna will always allow me to have a good Sicilian coffee before getting to work :

The link "The current death toll appears to be 8 (video)" does not work but try this:

http://www.dn.se/webbtv/nyheter/se-bilder-fran-vulkanutbrottet-pa-sumat…

Is Sinabung monitoring data publicly available?

@Boris Behncke, Catania, Italy, I am sorry to ask you here. But did you get my email, or did it get lost in the black hole of the internet known as /dev/null.

As for the Sinabung volcano, the few indicators that I get are no good. This eruption appears to be on the phase of dropping and re-starting again with more power. Given the few and little data that I get. But overall this does not look good at the moment. It is also a big factor that the volcano is awakening from a long period of dormancy, and that might not be a good thing.

I am assuming (given the data) that new magma is pushing out and re-warming older magma that was left in the magma tubes inside the volcano since the current eruption started. When the new material might reached the surface is a good guess, but I think that is going to happen sooner rather then later.

Even if events this far bear an uncanny resemblance to both Tambora and Pinatubo, that's not to say a major eruption is inevitable.

Or? ;)

Here is a new news from BBC News.

www.bbc.co.uk/news/world-asia-pacific-11127918

It is interesting to notice that the eruption is bigger the second time then in the beginning.

"Is Sinabung monitoring data publicly available??" (Mr Moho #5)

According to http://www.thejakartapost.com/news/2010/08/30/mt-sinabung-erupts-after-… PVMBG head (Dr?) Surono is quoted as saying "We never monitored the development of Mt. Sinabung because it was considered extinct".

The same article explains the division of Indonesian volcanoes into A, B and C as follows: "The center classifies type A volcanoes as having erupted at least once since 1600, type B as never having erupted since 1600, but showing signs of volcanic activity, and type C as never having erupted in recorded history."

This makes sense in a country with hundreds of volcanoes to monitor and limited funding to do so. Before we shake our heads, how well is - say - Colli Albani or the EEVF monitored...?

I know that correlation does not imply causation, and history does not always repeat itself. However, Sinabung has a neighbor (Toba) with a very bad reputation, just over 30km to the southwest. I would think that the proximity of the two would warrant a little extra caution in the case of Sinabung. The evidence of what can happen during a worst-case scenario eruption is a 35-100km caldera that is located right next-door.
I know that another Toba, Tambora, Krakatau, or even a Pinatubo is unlikely; however, I'd keep my distance!

Here is a You Tube video of Sinabung erupting.

http://www.youtube.com/watch?v=_nrTercH_Es

Quake felt on Mount Sinabung. Tuesday, Aug 31, 2010
www.thejakartapost.com/news/2010/08/30/quake-felt-mount-sinabung.html

A five-minute earthquake rattled villages near Mount Sinabung, North Sumatra, on Monday as the volcano continued to spew ash clouds.

Irfin Dian, a Kabanjahe resident, said the temblor was felt for five minutes, before Mount Sinabung spewed thick black clouds.

@Doug C., The problem is that the government of many countries don't think like that.

This same issue is also in place in Iceland. Where a string of volcanoes is not monitored at all. Even if some of those volcanoes did erupt about 1000 to 1500 years ago. Those volcanoes are on SnÃ¦fellsnes peninsula. So this problem is not unique in Indonesia, far from it.

The unmonitored volcanoes of Iceland.

www.volcano.si.edu/world/region.cfm?rnum=1700

Doug C. (and others) - Tread carefully when trying to connect volcanic systems like that. Remember, these are volcanic arcs where volcanoes are close to each other, but horizontal distance doesn't mean much in most cases. I mean, we don't worry about Mt. Adams erupting if Saint Helens is active even though they are quite close together. There are examples where the systems appear to be interconnected (or at least stacked) such as Katmai, Alaska (1912), but linear distance is never a good way to connect volcanoes without other evidence.

Erik:

One reason for the discrepancy between the Volcanic Ash Advisory Center and Indonesian reports of ash plume height may be the elevation of the summit. VAACs give heights above sea level, and the Indonesia authorities appear to be giving heights above the 2,460-meter summit. 2,000 + 2,460 is pretty close to the 6,000 meters reported by the VAAC.

One question: You mention that you suspect there is little new magma in the system, but reports I've read state that there are lava flows on the surface. Is this consistent?

thanks

#12 There's a link for earthquakes from Indonesia Met Service
http://www.bmg.go.id/60gempa.bmkg?Jenis=URL&IDS=9279258135813849788
They had a 5.2 EQ, in Papua and another 4+ in Miamar, but too far from the area of our interest.
@Passerby I believe both an eruption and a strong earthquake are likely at the Great Sumatran Fault. The next strike slip megathrust is expected at the plate boundary, but further to the South (Padang region).
@Lurking, quakes in Indonesia are so large that you can't tell precisely if they are tectonic or volcanic. Hope the link above gives us some more info on the smaller ones.

Another at a local newspaper saying that there were six volcanic quakes yesterday in Sinabug:
"Kabanjahe - In accordance with data obtained by the Online Alert Sinabung from post disaster response in Karo Regency Road Veterans Hall Kabanjahe, volcanic earthquakes have occurred six times in Sinabung between the hours of 00:00 pm - 7:15 pm, today". Nice picture form the volcano.
http://www.waspada.co.id/index.php?option=com_content&view=article&id=1…

According to the "Jacarta Globe"
"A total of 30,052 people have been registered at 21 camps as of Monday afternoon, up from about 19,000 on Sunday, according to the North Sumatra Search and Rescue Agency."
They also mention "numerous cases of diarrhea".
http://www.thejakartaglobe.com/home/as-mount-sinabung-continues-to-rumb…

R Simmons - I've been trying to find a reliable source about the lava sighting, but there is nothing yet. My hunch is that it could be rock being lit from glowing in the crater mistaken as lava, but that is just speculation. However, if lava is confirmed, then that is definitely new material.

The historical eruption record of Sinabung should give a clue about the developement of the ongoing eruption. Volcanoes tend to repeat themselves. For example in the case of Mount Pinatubo the vulcanologist saw the marks of ancient violent explosive events in the terrain at the volcano and could expect the same type of eruption again. And the explosive eruption did happen. The same thing with Sinabung, what does the historical eruption record at the volcano tell the vulcanologists this time?

I found a snippet of video that shows a glow near the end, and a photo. Neither is particularly clear.

http://www.asiaone.com/Multimedia/News/Story/A1Multimedia20100830-10791…
http://www.thejakartapost.com/news/2010/08/29/mount-sinabung-sumatra-er…

>what does the historical eruption record at the volcano tell the vulcanologists this time?

Damn little. The updated wikipedia page reports,

>scientists were unfamiliar with the characteristics of the volcano, due to it having been dormant for so long.

From the Pinatubo wikipage,

>Although there seems to be no local knowledge of the previous large eruptions in the Pinatubo area, several Aeta residents reported in 1991 that their elders recalled small explosions in the past. Pinatubo was a known geothermal area before the 1991 eruption, and small steam explosions are quite common in such areas. It was only after volcanic activity began in 1991 that geologists studied the eruptive history of the region in any detail. Eruptions at the site can be divided into two major eras.

It was only after the eruption that geologists determined 'modern Pinatubo' (differentiating it from ancestral volcano active 1+ MYA) previous eruption history:

'Earlier large eruptions occurred 17,000, 9000, 6000 â 5000, and 3900 â 2300Â± years ago.'

That is the extent of the similarity between Pinatubo and Sinabung: they both were relatively unstudied until they erupted, and they have small eruptions and were geothermally active.

Prehistoric eruptive history of Sinabung is unknown at present.

Villard: that's one of the things about Sinabung that is so worrying; has there ever been a detailed geological survey of it? There is probably something gathering dust in some Dutch academic archive and all-but forgotten, (as the 1930s identification of Lamington as a volcano was forgotten) which might give some clues. In Pinatubo's case PHIVOLCS had to start more or less from scratch, and fortunately the volcano gave them time to do it

Lake Toba, a supervolcano is nearby? Correct?

Just to say Thanks to Boris....your blog is really nice, so I'm totally addict. I've seen your pictures from Etna...and I can recognize one with the lava's flow on the building...I've here when I was 11 years old...
I've no more reason not come on Sicily at the last spring...to see Mr Etna and miss Sea....
Thanks a lot for all your staff on the Net...I have a look on Eric and Boris Blog every night...
Muriel

New eruption at Sinabung in Indonesia

eklemetti — Sun, 29 Aug 2010 08:13:33 +0000

New eruption at Sinabung in Indonesia

Sinabung on Sumatra erupting on August 29, 2010.

Eruptions readers were quick on the news about the new eruption at Sinabung in Indonesia. There isn't much known about the eruptive history of the volcano - checking out the Global Volcanism Program, the last activity at Sinabung might have been an explosive event in 1881 with persistent fumaroles up until 1912. However, most news sources are quoting 400 years as the last known eruption of the volcano, apparently information from the Indonesian government.

The eruption itself appears to be an ash-rich explosion with ash fall reported up to 30 km from the volcano although the ash column from the explosion was only 1.5 km (~5,000 feet) tall. The volcano had been showing signs of activity with smaller explosions and minor steam-and-ash plumes on Friday, but the explosion on Saturday was much larger than expected. From the details I've read, [speculation] I wouldn't be surprised if there is no new magma (juvenile material) in this eruption, but rather just older material that was in the conduit. My hunch is that this explosion might be the start of more and the heat from the magma interacted with groundwater near the summit to cause the explosion - a very common precursor activity at a composite cone like Sinabung (think about the events leading to the eruption at Redoubt).[speculation] However, Surono, head of the Indonesian Center for Volcanology and Geological Disaster Mitigation, warned that "we have little knowledge in terms on its eruptive patterns and general forms."

A closer look at the August 29, 2010 eruption of Sinabung. Image by Binsar Bakkara/AP.

Thousands of people have needed to evacuate their homes around the volcano on Sumatra after this explosion - however, some have stayed behind to prevent the looting of their property. A 6-km exclusion zone has been set up around the volcano by the Center for Volcanology and Geological Disaster Mitigation as well.

eklemetti Sun, 08/29/2010 - 04:13

Tags

This could be a very nasty surprise. Like Krakatau or worse.
Composite Volcanoes are not to be complacent about (ask us
in the Pac NW. of the US..)

I think this image from yesterday taken by Terra/MODIS may show the eruption. (Warning: large image.) There's some high level gray clouds that may be ash, and a small grey mark underneath in the vicinity of Sinabung. The volcano is just slightly to the northwest of the Toba caldera.

(My posts seem to be getting caught in the spam filter. Hopefully this one will go through.)

@PeakVT Your posts might get trapped because you use the 'named' link feature.

Here is your Terra/MODIS image juxtaposed with the Google Earth location image. "A" marks Sinabung

http://i37.tinypic.com/atm7bs.jpg

More pre-eruption pictures available at Panoramio. Zoom the map out to locate further images.

http://www.panoramio.com/photo/14329723

Thanks for the warning and the image. It looks to me like the small grey puff definitely is Sinabung. There's not much of a plume compared to EyjafjallajÃ¶kull. Hopefully it will stay that way.

http://commondatastorage.googleapis.com/static.panoramio.com/photos/ori…

It looks like that the volcano is doing cleaning house, or a small pre-eruption phase to a larger eruption. So there might be more to come. But due to lack of data it is hard for me to know when that might happen, so I am not going to speculate on that.

Only time is going to tell us what happens. But given the fact that his is around the area where several Mw7.0+ earthquakes have happened, I am surprised that this didn't happen sooner that a volcano started erupting in this area.

Hi everyone!
That panoramio pic is quite interesting. Does anyone know the story behind all those words made with rocks?

Here's another shot. Messages to the Gods?

c0278592.cdn.cloudfiles.rackspacecloud.com/original/518838.jpg

this erupting vulcano lies only 30 km or so from the supervulcano Toba... i wonder why nobody worries about that...

wikipedia says:

Lake Toba is the site of a supervolcanic eruption that occurred 69,000-77,000 years ago, a massive climate-changing event. The eruption is believed to have had a VEI intensity of 8. It is believed to be the largest explosive eruption anywhere on Earth in the last 25 million years. According to the Toba catastrophe theory to which many anthropologists and archeologists subscribe, it had global consequences, killing most humans then alive and creating a population bottleneck in Central Eastern Africa and India that affected the genetic inheritance of all humans today.

http://en.wikipedia.org/wiki/Lake_Toba

#5 #7 I don't like this... After 400 years of dormancy, how many volcanoes are known to wake up "peacefully"? Any records of other such examples? According to Google Earth and SIV, there is a neighbor volcano (15 km to the NE), Sibayak, that emitted an ashcloud in 1881.
And actually, this is not only an area of 7+ quakes. There were too megathrust EQs in the last 6 ys or so, with epicenters less than 300 km apart, revealing a complex net of faults in the area. Besides, it is less than 35 km away of the deadliest caldera in historical time, Toba, a lake stretching 90 km across. Too bad we lack of data on this because I think there is some reason to get worried.

#11 I meant "two" megathrust EQs. (9.0 - 2004; 8.6, 2005)

@ Princess Frito (#8): I've seen it in other craters as well, one of them being Puy de Pariou in France: http://commondatastorage.googleapis.com/static.panoramio.com/photos/ori…

I guess it's kind of the same as those little rock piles that can be found on a lot of mountains.

Anyway, it's way too early to even think about words like 'Krakatau'. I was even somewhat surprised that the eruption made the headlines of Dutch national radio this morning.

@ JÃ³n FrÃmann: after December 26, 2004 an increase in eruptions in northwestern Sumatra wouldn't have surprised me. But then again, so relatively little is known about the effects of major tectonic earthquakes on volcanic systems. Btw, haven't you thought of maybe putting some helicorders in the Eifel ;-) ? I guess the area could use some ^_^ .

#10 #13 #11
@Gijs de Reijke: Even if there aren't such effects (EQs triggering eruptions), we are dealing here with an intricate faulting system relatively close to a triple junction. If you look at the image posted by Princess Frito you can see two of the various dormant volcanoes in the area (my guess).
And here is another dormant volcanic complex 110 km to the NW of Sinabung according to Wikipedia:
"Mount Kembar is a Pleistocene volcano, located in the northern Sumatra island, Indonesia. It contains a fumarole field, named Gayolesten. The volcanic complex is located in the junction of two geological fault systems and it is a shield volcano."
I'm no expert, like JÃ³n, and I think he's absolutely right in his concern.
There's no reason to take for granted that the whole region is out of risk and maybe this small eruption is an alert to Indonesian authorities to be more careful with this particular zone.

Im not a scientist...but this happening now...I dont like...Is it some links, data to observe this vulcano?
pardon for my english...and thanks guys in this forum helping to educate/inform us!
/lena

Thanks Gijs. I've never seen that type of environmentally-friendly graffiti before so I did a double-take. Sadly, in a few other shots of Sinabung, there are rocks with spray paint on them. :(

In the list of Sumatra volcanoes at Wikipedia Mt. Kembar is the only shield type volcano (Lake Toba labeled as a tectonic-volcanic type and Sinabung, a stratovolcano).
My questions here are:
1. How many instances of shield volcanoes, which are generally associated with rifting and hotspots, do we have at subduction zones (really don't know the answer).
2. Could we even think of another type of deeper source of rising magma related to this area between Toba and Kembar?
This is mere speculation of an amateur. @Passerby?

@ Renato Rio (#14): Yeah, I agree that it is a very interesting setting. That's why an eruption any time between now and 2004 wouldn't have surprised me at all. But like I said, the area's complexity probably makes it all the more difficult to understand what's going on there.

@ Peter van Rooij (#10): huge systems like Toba usually require more time (hundreds of thousand of years, if not more) to produce enough eruptable magma for an eruption the size of what produced the 'Young Toba Tuff' around 74.000 years ago. I don't think a big earthquake by itself 'shakes the bottle' enough to produce an enormous eruption at Toba at this point in time.

Looking for entryway to Indonesia Geological Directorate, Center for Volcanology and Geological Hazard Mitigation, Bandung, Indonesia.

None of my old links work, which is a shame because they had a crackerjack website with daily updates on 60 major volcanoes that span the Center's monitoring program; Indonesian government has undergone a de-centralization process. The old eruption volcanic monitoring site is gone. The public portal to the geological directorate isn't helpful - zero direct links. WOVO links are old.

What we want:
http://pvmbg.bgl.esdm.go.id/joomla

Director portal
http://www.bgl.esdm.go.id

@Passerby: Only director portal works for me. Of course, in Indonesian. For some reason Google translator works better in Portuguese(!!!??) Because of East Timor?

@ Renato

There are a lot of known shield volcanoes in subduction zones, for instance the Masaya volcano in Nicaragua (that is close to the Apoyo crater lake which could be a resemblance)and several shield volcanoes in the Kamtschatka Peninsula. I'm also doubting wether the Simbalung is connected to Lake Toba. Such as the proclaimed connection between Eyjafjallajokull and Katla. It is interesting to think about however without any proof.

Off Topic...
i continue to watch the earthquakes in Iceland
and was wondering if anyone else thought
Upptyppingar might erupt?
Anyone who knows more than i got an oppinion?
And that would be everyone ;)

Thanks in advance.
Best!motsfo

#22 @Maik:
Thank you very much for the information. I was just doing my research and found many "andesitic shield volcanoes" in USA (Alaska, Cascades) and elsewhere . Kempar, Indonesia, happens to be of this type. (http://www.volcano.si.edu/education/tpgallery.cfm?category=Shield%20Vol…)
As for the Toba connection, it was pure speculation on my part. I try to be careful about such things as to look for imminent catastrophes, but since we had been discussing earlier about other possible mechanisms involved in intraplate volcanism (which is not the case here), such as crustal thinning due to underlying faults, I thought that, like it has been supposed for Krakatoa (Wikipedia), a thinner underlying crust could also explain the explosive origin of Toba's caldera, and that such thin crust could also be present under the segment of Sumatra Fault from Toba to Kempar, since a similar faulting pattern is present there.
As for Katla and Eyjaf's connection, for what I've been reading, I'm still not 100% convinced there are no connections, but I'm getting there too.
#23 @Motsfo: According to more knowledgeable people at this blog, those quakes are purely tectonic (see earlier threads).

#24 Correction: Kembar, Indonesia.
http://www.volcano.si.edu/world/volcano.cfm?vnum=060106=A

@Passerby @Maik:
The more I dig in my quest for understanding the more puzzled I get. I thought the question about the existence of shield volcanoes at subduction zones was solved. But I went on, and here I am again, sharing my doubts with you guys. Feel free to ignore it, but I thought that maybe they could heat up the debates over this thread. (OK. After this post I must say good night and go back to my errands).
Shield volcanoes = volcanic edifice formed either by more fluid, mafic magma, poor in SiO2, or pyroclastic surges (???!!!! - which means "very explosive eruption"), providing a wide angle of magma deposit.
Andesitic magma = felsic, high SiO2 content.
Then I stumbled on this article (http://www.nature.com/nature/journal/v461/n7268/full/nature08510.html#B1) - abstract, calling for "A dearth of intermediate melts at subduction zone volcanoes and the petrogenesis of arc andesites"
My question: how come there be "andesitic shield volcanoes" other than formed by SiO2 rich pyroclastic flows of explosive etiology? We are supposed to find conical-shaped "andesitic stratovolcanoes", because of their highly viscous lavas, but not "shield-shaped".
So, I'm kind of back to where I started:
Could Kembar be one of this type of "explosive" andesitic shield volcano, relating it to Toba's explosive genesis?
Thanks for reading this.

RR pointed out: According to Google Earth and SIV, there is a neighbor volcano (15 km to the NE), Sibayak, that emitted an ashcloud in 1881.

If you look at the near neighbor, you're struck by the visual similarity of these two stratovolcanoes.

www.indonesiavolcanoes.com/mount-sibayak-trekking.htm

I think Erik is correct. A push of magma up under the volcano has caused ejection of old material and brought Sinabung to the same state of simmer as it's neighbor.

I would, therefore, look also at Mount Sibayak for clues of increased activity.

Geothermal Setting:
'Thermal manifestations Hot springs and steaming grounds are distributed in the southwestern part of the Singkut caldera. High-temperature fumaroles and solfataras exist on the top and also on the southeastern part of Mt. Sibayak. Temperatures of hot spring water range from 30 to 63Â°C.

'Hot springs are also situated outside the caldera; at Sinabung area about 14 km southwest of Mt. Sibayak, and Negeri Suoh area about 7 km southeast of Mt. Sibayak.

Discharge waters at Sinabung are of low to moderate
temperature and of bicarbonate-sulphate type. Discharge waters at Negeri Suoh have temperatures in the range 40-60Â°C.

Geological setting (excerpt):
There has been a complex volcanic history in the area with a number of eruption centres developing over a considerable period of time within the Quaternary.

The geological structures in the Sibayak area are mainly controlled by volcanic and tectonic processes. The caldera structure, elongated NW-SE, developed after the Mt. Singkut volcanic eruption. Some fault structures within the caldera are oriented NW-SE, and are parallel to the Great Sumatra fault...

Source: Optimization of power production, SIBAYAK GEOTHERMAL FIELD. (Geothermal Training Programme, Report 16 (2004) ReykjavÃk, Iceland.

Righto. We have a roughly triangular area rich in hot springs that parallels the Great Sumatra Fault.

en.wikipedia.org/wiki/Great_Sumatran_fault

'The Indonesian island of Sumatra is located in a highly seismic area of the world. In addition to the subduction zone and the associated Sunda Arc off the west coast of the island, Sumatra also has a large strike-slip fault, the so-called Great Sumatran Fault, running the entire length of the island.

This fault zone accommodates most of the strike-slip motion associated with the oblique convergence between the Indo-Australian and Eurasian plates. The fault ends in the north just below the city of Banda Aceh, which was devastated in the 2004 Indian Ocean earthquake.

>>>>After the December 2004 earthquake, pressure on the Great Sumatran Fault has increased tremendously, especially in the north.

We have the northern end of this island dominated by a constrained and very large and powerful fault, that has increased in activity *markedly* since 2004. The volcanoes of interest lie parallel to this Great Fault.

Now we have a jump in magmetic intrusion below a very quiet volcano considered 'safe' until a few days ago, having a more active neighbor with 2 active vents. We have geothermal field that supported the first power plant in Indonesia, one that is slated for expansion shortly.

I wouldn't be worried about an eruption. I would be very, very worried about another massive earthquake in the area.

Somebody tap on PVMBG's horn and get their attention. They have dozens of able geologists who should be looking for signs of rapidly increasing groundwater pressure, pronto!

Couldn't resist a quick lurking and... bingo!
Hope the guys at PVMBG show your lucidity, Passerby.

Sorry about the lack of posts....well the volcano bussiness is off season
I've been not only frantically prepping for class and my Eyja talk....any news from Pall Einerson?
or from the volcano front
i dont see nothing coming from icelandic univ's
at least some sismic data

Looks like another eruption, this time to at least 20,000 feet.

IDD41300
VA ADVISORY
DTG: 20100830/0038Z
VAAC: Darwin

VOLCANO: Sinabung 0601-08
PSN: N0310 E09823
AREA: Sumatra
SUMMIT ELEV: 2460M

ADVISORY NR: 2010/3
INFO SOURCE: CVGHM
AVIATION COLOUR CODE: RED
ERUPTION DETAILS: CVGHM REPORTED VA TO FL200 AT 30/2330Z.

OBS VA DTG: 30/0030Z
OBS VA CLD:
SFC/FL200 N0315 E09830 - N0305 E09720 - N0205 E09810 -
N0315 E09830 MOV SW 10KT

FCST VA CLD +6HR: 30/0630Z
SFC/FL200 N0315 E09830 - N0255 E09655 - N0130 E09725 - N0315 E09830
FCST VA CLD +12HR: 30/1230Z
SFC/FL200 N0315 E09830 - N0240 E09550 - N0100 E09645 - N0315 E09830
FCST VA CLD +18HR: 30/1830Z
SFC/FL200 N0315 E09830 - N0205 E09500 - S0020 E09625 - N0315 E09830

RMK: VA NOT IDENTIFIABLE ON SAT IMAGERY DUE TO METEOROLOGICAL
CLOUD. FORECAST BASED ON MODEL OUTPUT. NOW AT CVGHM ALERT LEVEL
4 [HIGHEST], SITUATION WILL BE CLOSELY MONITORED. Graphic at
[lower case] http://www.bom.gov.au/info/vaac/advisories.shtml
NXT ADVISORY: NO LATER THAN 20100830/0630Z

Really nice little reference maps of the tectonic setting of Sumatra, the Great Fault and volcanoes of North Sumatra.

www.tectonics.caltech.edu/sumatra/sumatranfault.html

Pay particular attention to the Interceptor FZ, the Central Domain, and the velocity vectors in the top map, before opening the large lower map and locating our two volcanoes of interest.

@motsfo, The Upptyppingar case is interesting and that would be a understatement. According to my ideas, and the ideas that I base that on. The Upptyppingar appears to be a volcano in formation. It has not erupted yet as a volcano with a magma chamber. But it is going to do so at one time in history. When that might happen I do not know.

If we are extremely lucky we might get one off cone volcanoes there in less then 5 to 10 years. But I am expecting big eruption in 30 to 50 years, based on current models and given the number of earthquakes. But only time is going to tell me what is going to happen, and how this is going to evolve at Upptyppingar.

According to an article in the German news magazine 'Der Spiegel' locals reported seeing lava flowing from the Sinabung volcano:

http://www.spiegel.de/wissenschaft/natur/0,1518,714420,00.html

The google translation reads as follows:

"Local media reported, citing witnesses, leaking lava was seen from miles - even in the tourist area of Berastagi to the north of the island. Volcanic ash from the 2451 meter high volcano had reached the provincial capital Medan.

"At midnight there was a severe blow - one suspects a volcanic earthquake," said Irsal. "Soon after we saw lava running down from the top of Sinabung and fire burned the forest at the foot of the mountain."

Here the original:

"Lokale Medien berichteten unter Berufung auf Augenzeugen, auslaufende Lava sei aus mehreren Kilometern Entfernung zu sehen gewesen - auch in der Urlaubsregion Berastagi im Norden der Insel. Vulkanasche aus dem 2451 Meter hohen Feuerberg habe die Provinzhauptstadt Medan erreicht.

"Um Mitternacht gab es einen starken Schlag - man vermutet ein vulkanisches Erdbeben", sagte Irsal. "Kurz darauf sahen wir Lava vom Gipfel des Sinabung herunterlaufen und Feuer verbrannte den Wald am FuÃe des Berges.""

But I don't know, if those observations were confirmed from independent / qualified sources.

Here is a picture series from BBC News on the eruption.

www.bbc.co.uk/news/world-asia-pacific-11126417

Not much to look at... I can't find any listings with lower magnitude quakes, so your not gonna get much more than an overview. That is one of the beauties of Iceland and Italy, nice quake lists.

Mag 4.0+ 1973 - 2010, Sinabung location +200km circle. Perspective view. USGS data source. (easier to pull and has depth info, unlike the site in country)

http://i38.tinypic.com/2mmtjpk.png

So, I come back and what we have here? - an eruption with a significant ash plume, wood fires from lava emission, a huge earthquake in perspective and a magnificent plot showing the subducting slab under Eurasian plate!
You guys want me to get "fired" too?

Yep the volcanes are acting up again. This one may be big so I will be sure to keep track of it for the coming weeks.

I'm just passing by and looking for some information related with the recent eruption of sinabung this morning at 6 AM (Local time). I'm indonesian and know too little about volcanism, could u all give a opinions of worst case scenario that might happen here with this mountain?

@Lurking:
Could you show us a N-S and a E-W view? Or maybe just a flat view to get a perspective of the Sumatra Fault.

@Adibrata:
Good morning. Hope you're doing well. From what part of Indonesia are you typing? So far, we are having some news of an ashcloud (post #30) and rumors of some lava pouring out from the summit (#33). Maybe you are more up to date with local information.

Try the Figures

www.nature.com/nature/journal/v440/n7080/fig_tab/nature04522_ft.html

to this paper: Nature 440, 46-51 (2 March 2006)

Plate-boundary deformation associated with the great SumatraâAndaman earthquake.

www.nature.com/nature/journal/v440/n7080/full/nature04522.html

The last figure will help you put Lurkings timely plot into perspective. The first figure is a neat graphic, showing the fault segments and the last dates of rupture.

Although you might not be able to read the paper, in this case the accompanying figures speak for themselves.

@Passerby
On the reference maps of Sumatra tectonic settings, could you please explain what is the red dotted circle across Toba lake?

Short footage on Sinabung by the Portuguese television. They also mention "lava pouring from the summit".
http://tv1.rtp.pt/noticias/index.php?t=Vulcao-Sinabung-entrou-em-erupca…

@Adibrata Could you translate the main story here for us? With more information, we might be able to help you. Thanks.

http://www.metrotvnews.com/

The Sama dengan kejadian hari sabtu story? Also, is the Dua Ruko di Surabaya Hangu Terbakar story related to the eruption? If so, where are the office buildings that caught on fire? Thanks very much.

Thank you @Passerby. Now it is Good Night!

Sibayak, Sinabung and Toba share a common feature. They straddle the Sumatra Fault.
Sinabung sits out on a lava plain by itself. Sibayak is a volcanic cone straddling the side of the Singkut Caldera.
There are domes every where around the surrounding area in between Toba and Berastagi. Sibayak and Sinabung are obviously active as they emit sulfurous fumes.

Local history states that both Sibayak and Sinabung showed some activity in 1881. This may be coincidence but I'm not sure of the two cones share exactly the same magma source.

There are around 500,000 people in the surrounding areas of the eruption area. 60kms to the Northeast sits Indonesia's third largest city - Medan. If a major eruption took place at Sinabung there would be a bit of a problem for all these people.

The fertile plains around this volcano are a major food producing area with a huge export business with Singapore and Malaysia.

@Renato Rio: Well, I'm in Jakarta right now, but still, with a country like Indonesia, we don't expect another natural disaster happen in indonesia soil, because the impact will be huge..
@parclair, NoCal: I believe those two news is not connected, the two Ruko (office building) is located in Surabaya (East Java).

@42, RR Subducted fault zone, in line with the yellow arrow.

@46

>Sibayak, Sinabung and Toba share a common feature. They straddle the Sumatra Fault.

They do not. They *may* straddle a transverse fault system not shown on the Cal-Tech map. The geothermal field-power station engineers will know.

News report on the 2nd eruption that occurred Monday, as reported by Chance, #30, ash to ~2 Km.

news.xinhuanet.com/english2010/world/2010-08/30/c_13468893.htm

Re: Renato Rio[39]

Okay, but like I said, it's not much to look at. Remember, this is a plot of all quakes since '73 as they appear in the USGS catalog. It was used because the in-country catalog was less than helpful (no depth info). That doesn't mean that there isn't a better catalog that I just haven't found or have access to.

North view, looking through the the fault plane:

i38.tinypic.com/160o7eo.png

East view (looking east), not fully in line with the fault plane:

i35.tinypic.com/24q8glg.png

And a plan view:

i37.tinypic.com/9ql0ew.png

The lack of sub mag 4.0 quakes pretty much rules out being able to plot magma paths, cracks and creaks.

There's a huge discrepancy surrounding the height of the 2nd eruption. Post #30 says 20,000 feet whereas post #49 says 2 kilometers.

Which is it?

Plan view: almost like a back arc volcanic group from subduction melt upwelling. Super interesting to see the fine structure from 3 directions and in 3-D.

Oh Goodie! Deep-focus EQs.

Excellent work; thanks again Lurking!

several pic taken this morning at 6 AM (local time)
http://foto.detik.com/readfoto/2010/08/30/090614/1430742/157/1/gunung-s…

@Adibrata 53. Wow. That eruption looks serious. Thanks for the link.

I'm no epxert in this, but have some interest in volcanoes.

I noticed the new pictures on BBC (http://www.bbc.co.uk/news/world-asia-pacific-11126417) seem to show a double column of smoke, one at an angle. multiple vents?

@Willem

I'd be interesting in knowing the time relationship of that image verses the the one linked in post 53.

The plume on the left is definitely being shot out almost horizontally, then turning upward from the heat.

If the vent was partially obstructed, did it clear, making the image from 53 possible? Or is this something that fell and obstructed the vent shown by 53, possibly causing the twin plumes?

Very nice photos there Adibrata, thanks for posting that link.

I'm due to get into Medan tomorrow afternoon, around 3pm local time. I'll be there for about 4 or 5 days and will endeavor to post photos and updates on the eruption here...

The situation at Sinabung reminds me of a number of very different volcanic events, some of which culminated with large, destructive eruptions, whereas others calmed down after some time without growing really big and dangerous.

So far the eruption appears to be phreatic, maybe the initial explosions unleashed hot material (you can see incandescence in video posted on YouTube: www.youtube.com/watch?v=GQz8co21wAs) but certainly NO LAVA FLOW. Fluid, Hawaiian-style lava does not come out of this type of volcano, especially not at the start of a new eruption after long repose. Maybe there is a lava dome pushing from the summit, although I would expect this to happen later on, after the path for the rising magma has been cleared.

There are indeed spectacular photos at Daylife, which show that there are several vents at the summit and on the side of the volcano:
www.daylife.com/photo/0e6T0SP25Vbfx?q=volcano
www.daylife.com/photo/037rcQD2gSdXb?q=volcano
www.daylife.com/photo/04bUeSkcd33Px?q=volcano

Three scenarios can be envisaged:

(1) SoufriÃ¨re de la Guadeloupe (1976-1977) - phreatic explosions and probably magma uprise, without culminating in a magmatic eruption; similar events have occurred at Fourpeaked (Alaska) in 2006, Koaryaksky (Kamchatka) in 2008-2009 and numerous other volcanoes. One particular example is Ontake in Japan, which erupted in 1979 after possibly up to 30,000 years, but all that happened was a few phreatic bursts and then the volcano calmed down again.

(2) Unzen (1990-1995) - phreatic explosions followed by lava dome growth without much explosive activity. Much of the disaster caused by the Unzen eruption was due to collapse of the lava dome, which grew on a very steep, unstable flank and thus often crumbled, generating pyroclastic flows. A variation on the theme is SoufriÃ¨re Hills (Montserrat) where initial phreatic explosions were also followed by dome growth and frequent dome collapse, but there was also strong explosive (Vulcanian to sub-Plinian) activity.

(3) Pinatubo (1991) - initial phreatic explosions followed by dome growth and then a massive cataclysmic, caldera-forming eruption, which in turn was followed by lava dome growth.

A Pinatubo-like scenario is possible but less likely than the other two scenarios. If Sinabung behaves like Unzen, i.e. if it builds a lava dome at its summit or on its steep upper flank, there is a high risk of pyroclastic flows generated by dome collapse. Seismic and deformation monitoring is imperative here, to see whether a large volume of magma is making its way to the surface, as at Pinatubo, or whether it is rather modest and will produce a lava dome-building eruption.

Out of topic but certainly of interest, a little Etna update:

Since the strong 25 August phreatomagmatic explosion at the Bocca Nuova at Etna's summit, there have been numerous smaller and 8 medium-intensity explosions, the latter of which generated conspicuous but short-lived ash emissions. Observations made at close range disclose that these events are virtually noiseless, and the ejected ash is altered, lithic (old, not new hot magmatic) material so far.

Access to the summit craters of Etna is now prohibited by decree of the Prefecture of Catania. The situation is considered highly dangerous; during a strong phreatic or phreatomagmatic explosion at the Bocca Nuova on 12 September 1979, nine tourists were killed and more than 20 injured.

It is likely that the current explosive sequence is a vent-clearing activity, as magma is reoccupying the conduits of the summit craters. Evidence for magma uprise is also in the fact that fumarole temperatures on the crater rims and on the outer southwest slope of the central summit cone (which hosts the Bocca Nuova and Voragine craters) are rising, leading to increased sulfur deposition (at temperatures above 120Â° C).

Updates are posted in Italian and English at the INGV web site - www.ct.ingv.it

Thanks so much for that insight Boris, very interesting read!

A short clip from BBC: http://www.bbc.co.uk/news/world-asia-pacific-11128800

@#60 - Heh. Literally at cockcrow.

@Lurking:
There's an outstanding concentration of EQs under Toba (rather than at Sinabung) and since they aren't from the Great Sumatran fault, what are they? An unknown fault or Toba's own faulting system? - if I understood it right.
@Boris and all:
Thanks for the stunning pictures and posts. We we'll have a busy week from Indonesia and Italy. Keep safe you and Adibrata.

Don't like this. Hope it follows the more innocuous paths proposed by Boris. This could become a Plinian event hugely affecting nearby population (500 000). We need more tremor plots and GPS measurements. Where can you get them, Lurking?

A local newspaper (Google translated) is unsure of what to expect from this:
"Identification Difficult Vulkanolog Sinabung" (...)
"The team from Bandung Volcanology led Surono still can not decide what type Sinabung," says Head of Department of Energy and Mining, North Sumatra, Untungta Kaban." (...)
"Sinabung eruption in the middle of the night when it came to a radius of 10 kilometers. Even the dust up into the sky vulkaniknya Medan, a distance of approximately 150 kilometers from the eruption site."
http://matabangsa.com/index.php?option=com_content&view=article&id=1997…

Sinabung does not look like your normal (strato)volcano with a regular summit crater. Judging by the photos, it has more of a "flank" crater running from summit to about 2/3 of the way down...

I would be very suspicious of any volcano that suddenly starts erupting after centuries of dormancy.

I would be very suspicious of any volcano that suddenly starts erupting after centuries of dormancy.

Posted by: mike lyvers | August 30, 2010 6:42 AM

Like Chaiten for example?

www.dn.se/webbtv/nyheter/se-bilder-fran-vulkanutbrottet-pa-sumatra-1.11…

More video including aerial ones from the summit. According to this site, eight people have been killed.

@Boris:

There was news-footage of lava earlier today at the same place where you can actually see it at #53 pictures. Nice to see that even experts can be surprised by volcanos now and then.
Thanks for the list of possible things that can happen at Sinabung.

@all:

For those who cannot read swedish the article Henrik cited states that there are now 4 times as many dead from this eruption than the Eyja (8).

@Carl on Lava #69, I did in fact refer to the news footage where you see incandescent material - but that is not fluid lava. It is rather hot blocks falling from a lava dome, or vegetation set on fire by hot material. We should remember that also phreatic explosions can throw out rocks at temperatures of up to 800Â° C, which means they're incandescent, even though they are not derived from new magma!

Tragically (but not surprising), the news media are mixing up the Sinabung news with photos of all sorts of eruptions (including old EyjafjallajÃ¶kull).

New post ... and first day of classes!

http://scienceblogs.com/eruptions/2010/08/sinabung_and_etna_updates_for…

@Boris:
I guess that some idiot then had clipped in some nice bubbly burping lava in the news here in Sweden. Unusual that they do things like that here.

@Renato Rio [62]

That has more to do with how the plate is being subducted and in what regions stress and fractures build up.

The Toba caldera forming event was an easy 75 kyr ago.

It's very unlikely that a bag-o-quakes at 150+ kilometers deep on the folding area* of a subducting plate in the 1973 to 2010 timeframe has anything more to do with it than it does any other volcano on the island.

Remember that the plots do not have any quakes under 4.0. Just the larger ones.

Likely, a large quantity of quakes are there but just not available for plotting. If the ratio is anything like Iceland, then that number is HUGE, and is probably why they don't report every creak and pop. They also might nor have the same gear coverage as Iceland.

* I'm going with the folding idea, I think Passerby and others of that camp are dead on accurate.

We know that a prominent fracture zone is being subducted in the area of Toba and Sinabung. I suppose there might be a chance that bending crust that is 'prefractured' in an opposite orientation to bending axis could provide a route for magma flow to the surface. Just enough to provide hydrothermal heat source and fumaroles, but not vigorous eruptions in the recent past.

So one could guess that a build up of stress on the Great Sumatran Fault, perhaps near the segments which haven't been active in several hundred years - note that the old rupture dates roughly correspond to the approximate period of last known large eruption for Sinabung) - are under considerable stress buildup from the 2004 Aceh quake.

This is why I fear that a major EQ is much more likely than any large eruption, and why I concur with Erik that we're seeing old material being expelled under a sharp rise in pressure under Sinabung and perhaps under adjacent volcanic centers, given the anecdotal evidence of paired minor ash eruptions in early 1880s (same period as Krakatoa to the south, and mid-island Dempo and Kaba eruptions - all part of the southern domain subduction region of the GSF).

This is the provenance of the Cal-Tech group who has been chugging away on the tectonics of North Sumatra for a decade. We'll give them a buzz and see what they make of our idea.

planet-wise , the dates to watch out for are :- 5th to 9th
September , there are 6 planets in a 30 deg corner of space
around the sun .

@All: if anyone needs a hand in translating indonesian article from a local news, just let me know, sometimes even google translate not with a right grammar.. :)

little update from several local news today, there's no high activity today at mount sinabung, some analyst said that because the pressure at the magma chamber under the volcano is decrease..

What u guys think about this?

If we register at iranican.com to post blogs does our email get published? I see that your bloggers have their emails published.

[quote] Hi everyone!
That panoramio pic is quite interesting. Does anyone know the story behind all those words made with rocks?

Posted by: Princess Frito [quote]

i just googling about Mt.Sinabung then arrive here ^_^ thanks God cause i get more information unheard before about this Mountain, anyway I'm living here in 'Kabanjahe' [the capital of Tanah Karo] near Mt.Sinabung just about 20km [the Mount looks quite clear from here]
about Princess Frito question i guess the Rocks written was names [perhaps the names of the people who ever came there]
i also hope like Adibrata, maybe u guys who knows about geologic could share information for us, especially for us the people around this mountain...so we know what we have to face here... Thanks a lot ^_^ [i'm sorry if my english bad ^_^]
next time i'll share more pics i get during the eruption...

Is usually blogengine superior to live journal in some manner? Really needs to be because it's starting to be popluar lately.

Just keep posting good stuff.

I can't consider I have ever noticed a site with this particular lots of feedback into it!

Great stuff.. I am going to need a bit of time to entertain your site:D

Friday Flotsam: Galeras settles, Krakatau anniversary, what is under Yellowstone and more.

eklemetti — Fri, 27 Aug 2010 11:43:41 +0000

Friday Flotsam: Galeras settles, Krakatau anniversary, what is under Yellowstone and more.

Sorry about the lack of posts - I've been not only frantically prepping for class and my Eyja talk, but also I'm somewhat under the weather with an ill-timed sickness, so even though there is stuff to talk about, I haven't really had time/wherewithal to deal with it.

However, expect big things from Eruptions next week!

Drawing of a ship washed inland by the tsunami generated by the August 27, 1883 eruption of Krakatau.

I'll throw a few quick links:

The alert status at Galeras has been dropped back down to "orange" after the non-explosive eruption earlier this week. However, INGEOMINAS warns us the threat is still there (spanish) for an eruption (and more evacuations).
Another volcano anniversary falls this week - this time the 1883 eruption of Krakatau in Indonesia. You can even hear a witness to the actual eruption get interviewed by author Simon Winchester.
Curious about what is going on underneath Yellowstone - check out the great post on Highly Allochthonous that examines the source of the giant North American caldera system.
Dr. Boris Behncke has kept us appraised on the currently activity at Etna on his photostream - not a lot of coverage of this new activity at the Italian volcano in any other media source.
And you can catch up on all the week's volcano news with the Global Volcanism Program's Weekly Volcanic Activity Report!

eklemetti Fri, 08/27/2010 - 07:43

Tags

Global Volcanism Program

volcanoes and society

yellowstone

Eruptions readers who recall our technical chitchat here on deep focal earthquakes,

scienceblogs.com/eruptions/2010/07/climate_volcanism_and_the_ande.php

you will very much want to go look at Chris Rowan's blog entry for today, mentioned in Erics opener above.

Look closely at Fig 2B. What do we see?

We see what looks very much like a critical folding unit dimension of 200 Km.

The twisting corkscrew shape that Chris mentions is a massive torsional movement that is mirrored in the curving path of the hotspot, seen in the first blog figure.

I am thinking that we are seeing an interesting phenomenon:

The 'unpleating' of the folded subducted crust.

Recent tomography evidence of PNW crust subduction through deep focus EQ modeling (discussed in papers I presented in July, linked above) suggests that diving crust remains intact - stretched and thinned, but with structural integrity in place, as it descends to just below 800 Km.

So, I'm not what happens as it's mashed down into pleated folds, but it sure does look like it's a pleated and unfolding structure that is feeding upwards as the Yellowstone hot spot.

Now, with this picture in mind, look at the last set of modeled tomographic data. See the cold subducting crust plunge downward at the coast, being pleated and stacked at some critical depth (S2), and then an ancient fragment rising by convection, to emerge below and along the path of the Yellowstone hotspot?

Could be coincidence (the apparent pleated geometry), but if this is true, it's quite remarkable!

@Erik
We cannot be too grateful for your relentless endeavor in keeping us updated with all kinds of geological information whatsoever. This your blog is an outstanding example of generosity in sharing knowledge and arousing curiosity as a mean of improving our understanding of the world and the relationships between man, science and Nature.
And I also want to thank Boris, ECho and all the other collaborators, as well as our fellow bloggers who, with their valuable comments and posts contribute to keep this blog "rocking". It's been a thrilling experience to be around.
I must confess I'm still far from grasping the whole picture in which concerns magma and volcanoes, but I'm fascinated and eager to learn more.
I'm specially interested in understanding the mechanisms governing plate tectonics and hotspots. Although my expertise is yet insufficient to go deep into the matter, I daresay that, concerning the mantle plume theory, there must be some kind of gap between what is being explained and what is really taking place underneath. Except for Hawaii, where mantle plume provides a very plausible explanation for volcanism, there must be a link between sinking of old plates and hotspots elsewhere. We've seen that kind of connection in Iceland and Yellowstone and recent EQ activity in ancient subduction zones appear as good examples of weird behaviors of magma formation.
It has been said recently in this blog that the mantleplume.org would be a questionable source, though the article in Highly Allochthonous points to the site.
Maybe you could give us some opinion about this as well as some other reliable sources in the net (or books) where a layman like me could get a good perspective in the actual course of debate.
Many thanks in advance.

@Passerby
As soon as I have sent my last post I saw your comment on Chris Rowan's blog. I must give you a special thank for getting me into this debate and for the whole lot of fascinating homeworking you have been charging me with. I can already feel the good results, so I hope. :)

Renato, meet Dr. Foulger:
foulgerconsulting.com/Bio_GRF.html

I used her consulting cv, as it's more up-to-date than her faculty 'vita. She's certainly legit and so is her website.

Ah, the dreaded late-summer ick. Hope it clears your system soon!

@Passerby
I was thinking of buying the book, but I was afraid it would be too difficult to my present level, but since you recommend it, I'll give it a try. Many thanks.

Renato, I wasn't referring to her book, but to her website, in reply to your post query.

If you are thinking about trying her book, you should write to Dr Foulger and ask if it's appropriate for the general public. At the very least, you should work through the material on her mantle.org website.

#7 @Passerby
Yes, that is exactly what I needed when I addressed to Erik. I didn't notice the contents before I answered to your post. Cool! After going through the site I might as well be able to understand the book.
Oh, dear, and all my daily errands waiting for me...
Look what you've done to me! ;)

@Passerby
Just found what I wanted here: The Mantle Plume Hypothesis Pro and Con: Evidence from Earth's Most Voluminous Large Igneous Provinces.
"A common mechanism for the formation of LIPs is highly desirable, yet, at present, all existing hypotheses appear in some way deficient."
Yes. That's exactly what I meant, but to go deeper in the matter I'll have to wait till I have enough time to grasp the basics on seismology and petrology.
As they say in Italian: Piano, piano, si va lontano.

Start at the simple level and then move into Gillian's website, with a range of factual complexity.

www.rasmussen.edu/student-life/blogs/main/beginners-guide-to-plate-tect… (NASA recommended)

USGS, This Dynamic Earth - The Story of Plate Tectonics (online edition)
pubs.usgs.gov/gip/dynamic/

Introduction to Plate Tectonics
www.hartrao.ac.za/geodesy/tectonics.html

Virtual Upper Mantle
www.virtualuppermantle.info/

Geology.com earth internal structure
geology.com/nsta/earth-internal-structure.shtml

As they say in Italian (musical direction): poco a poco.

More recent mantle plume theory and discussion, Episodes, March 2007 (several papers, start with Dr Xu's intro)

www.episodes.co.in/www/backissues/301/301.htm

Since the Episodes volume 30 March issue mentions the OneGeology concept, introduced in 2007, I'll throw in the link to this global geology website.

www.onegeology.org/home.html

#13 Grazie infinite!

@Passerby
What an invaluable material!
All links are bookmarked and I'll take the weekend to start studying them "poco a poco" (actually, I've already started).
Now I'd like to repost a link to this RUV article. Do you have any idea of what could they be? Cracks being found along the Icelandic rift system?
"New cracks in Sprengisandur"
http://www.ruv.is/frettaskyringar/innlendar-frettir/nyjar-sprungur-a-sp… (Icelandic)
Thank you very much.

@1:

If I remember correctly you where the one *snorting* the most about my little brain-fast of the vorticing plumes/hotspots. I find it hilarious that you a few weeks later present the only "proof" of that idea so far. If I remember you even went to the trouble to suggest I should study fluid dynamics before saying anything... Haha!

The world is a small thing after all:)

@Renato: The geophysicist PÃ¡ll Einarsson thinks these cracks, brand new as they are, are somehow related to the eruption in VatnajÃ¶kull glacier in 1996.

Renato, the cranks are in the Highlands between HofsjÃ¶kull and VatnajÃ¶kull icecaps. It's a dry volcanic and gravel flood deposit plain. They're associated with area rift systems, and their appearance in Spring and Summer suggests erosional exposure at the surface from glacier melt floods.

If Pall Einarsson infers that they're related to the Gjalp 1996 eruption, he might be referring to crustal deformation effects of this event.

Crustal deformation associated with the 1996 GjÃ¡lp subglacial eruption, Iceland: InSAR studies in affected areas adjacent to the VatnajÃ¶kull ice cap, Iceland (2007).

homepages.see.leeds.ac.uk/~earcpa/article.pdf

See Figs 1, area 'T' (the rift system mentioned in the riv article), and 2 (interferograms, deformation maps). It's in the approximate area of the cracks reported a few days ago.

Article in English, I found this while reading the Icelandic news on recently formed melt lake to the West on the Ok glacier remnant, posted by birdseye.

www.icelandreview.com/icelandreview/daily_news/?cat_id=16567&ew_0_a_id=…

/en.wikipedia.org/wiki/Highlands_of_Iceland

#16 @Carl
I enjoyed very much all your talking about magma fluid behavior. Ever since then, I've been noticing that all plots and graphs concerning quakes distribution and lithosphere deformation, as well as rising magmas, exhibit a cork screw / semi helical pattern. Of course, there are many forces at stake here and we don't know exactly how the stuff in the mantle behaves, whether fluid-like or semi-solid, to state precisely if they go "by the book" in either way. But since we are no experts, we're entitled to do some speculation in this non academic forum and get ready for the criticism. I'm too far from giving my own opinion, but trying to gather some information on this.
What I've read so far draws me back from mantle plume and convection currents theories as being the main responsible for plate movement and magma formation and that gravity is still very much to be blamed. But this is a mere intuition on my part and I'm ready to be slapped on my face to be saying such a sacrilege. Passerby is helping us a lot with all the material he has been providing and I hope someday I'll be able to discuss the subject in a less amateur way. So, let him snort at his leisure. He has already showed he's ready to respond to the good discussion, as you can see in the deep EQ debate.
Love you guys!

#17 #18 @Reynir @Passerby
Thanks for your posts and links. When I read about these cracks I thought they would cast some light in our Icelandic debates, and wanted you guys to examine the finding. I'll take a look at the articles.

#20 I read the article. The crevasses provide evidence supporting Einarsson's hypothesis of slip faulting at TungnafellsjÃ¶kull area due to a 5.6 EQ under Bardarbunga and the 96 Gjalp eruption. Wonder if recent EQ activity to the N of Bardarbunga is anyhow related to this and since activity in the area is somewhat "enigmatic", as they say, we don't know exactly what to expect. The ice sheet there is too thick to give us precise GPS measurements and even to surely state if an eruption has occurred.
Fascinating.

The authors do a nice job of presenting possible explanations for deformation and then examining data in light of each case.

You asked for an explanation of the crevasse formation at this location, and since you posted an article quoting Einarsson's comments point to the 1996 eruption, I did the best I could to point to published study connecting cause and effect.

The authors noted deformation to the north as well as the NW. We have already discussed the potential for tectonic faulting absent of intrusions in some locations, and magmetic dike intrusions in others, to explain earthquakes covering a large area to the east of Askja, with many excellent plots provided by Lurking.

so in summary, what goes down must come up?

@Passerby, Renato Rio, Reynir, NK

I have no clue where "Goose Lake" or "New Valley" are at.

Following along, the best I can come up with is the general region between VatnajÃ¶kull and HofsjÃ¶kull.

So, in response to Renato Rio's musing:

"Wonder if recent EQ activity to the N of Bardarbunga is anyhow related to this and since activity in the area is somewhat "enigmatic", as they say, we don't know exactly what to expect."

A plot of this area and recent activity (since 8/1/2010)

I won't be doing many of these plots, I had to layer the quakes in level by level to get them on the background image.

http://i33.tinypic.com/nd6a90.png

Provided that I got the extents of the background image right.

(the lat and lon of the quakes are accurate)

SCRAP THAT

Corrected version.

http://i38.tinypic.com/eugbjc.png

Thank-you, Lurking.

If Renato will go to Fig. 1 of the 2007 paper cited above, he will see a reasonable match between recent seismic activity and that recorded between Sept 29 and Oct 13, 1996, predating the eruption.

That should answer your last question, RR.

For those of you who think I'm an idiot. Well, your partially correct. But lacking a way of editing my hose ups... I am a fully exposed idiot. Can't zip the fly.

@Renato Rio, etal.

Speaking of Gillian Foulger and plumes, this link may be of interest. I site-searched the scienceblogs.com blog and didn't see it anywhere already.

http://www.geolsoc.org.uk/plumesdebate

GÃ¦savÃ¶tn (Goose Lakes): 64Â°46.7'N, 17Â°31'W.

NÃ½idalur (New Valley): The mouth is at ca. 64Â°43'N,18Â°03'W. The valley was first found for certain ca. mid-19th century, hence the name.

Both are popular rest spots after a day of bouncing and jouncing on a fourby trail.

From the www.icelandreview.com link in Passerby's post [18]

"The crevasses are located a stoneâs throw away from the road between the GaesavÃ¶tn lakes and NÃ½idalur valley. "

And thanks to Reynir, NK's coordinate set on GÃ¦savÃ¶tn and NÃ½idalur, a replot (correctly oriented) with those locations and the background image constraints double checked.

http://i37.tinypic.com/hv5ftt.png

@Renato Rio, all

Please read each of the following books before giving an opinion ...

http://www.dgf.uchile.cl/biblio/Libros_nuevos/mostrarioSismologia.htm

Haha, just joking. Saw the list and thought of your quest for deeper understanding. Seems like a lot of work.

Famous Quantum Physicist Gerard 't Hooft says any dedicated person, young or old, can become a good PhD-level Quantum Physicist just from free material on the web. The following is a great read regarding acquiring scientific knowledge and expertise on one's on, and also the value of mentors to give guidance (eg passerby).

http://www.phys.uu.nl/~thooft/theorist.html#list

So it would seem, hopefully, the same would be true of Volcanology.

Here's an animated gif timelapse of yesterday's (Friday) venting from Etna's volcano craters. It is a 4.4 MB file comprised of 95 images taken by CAM 4 8:10 AM to 12:40 PM UTC,

http://i33.tinypic.com/30uajxt.gif

A total of 4 1/2 hrs played back in just a couple of minutes. The images were separated by 2 minutes 40 seonds, which is a limitation given by Cam 3's rate of updating. In this version of the animation, each image is displayed for 200 ms.

The action, like Thursday, started fairly sedated, but built in intensity over time.

Some curious action happens on the edge of the right-most crater .. just barely discernable.

Correction to above: 4 1/2 hours is played back in 20 seconds. So an hour goes by in approximately 4 1/2 seconds!

My dear mentors: I am a mess. I don't think I deserve to be the object of William's experiment on internet learning. Split between sciences and arts, I got stuck on a TV presentation of the last part of "Der Ring des Nibelungen" and missed my errands as well as my geological studies. I'll try to catch up on your recent posts and see what is behind Lurking's plots.
@Passerby: Do you believe we could witness a revival of 1996 around VatnajÃ¶kull any soon? Just caught four more quakes over HerÃ°ubreiÃ° area.
28.08.201023:37:5065.137-16.3965.8 km1.690.014.7 km SSW of HerÃ°ubreiÃ°
28.08.201022:43:2965.090-16.2637.7 km0.535.065.5 km N of Upptyppingar
Saturday
28.08.201021:58:0965.206-16.3005.2 km1.138.273.6 km WNW of HerÃ°ubreiÃ°arlindir
28.08.201020:34:5264.674-16.5081.1 km1.274.46.7 km NE of KverkfjÃ¶ll
28.08.201020:17:1165.082-16.2687.8 km0.644.654.6 km N of Upptyppingar

#29 @William M Boston: Great link. I ask your permission to quote one paragraph:
"Volcanism that appears to be anomalous (...) results from the inhomogeneity imparted to the mantle by plate tectonics and intraplate deformations that occur preferentially along pre-existing lines of weakness. The possibility of such a radical simplification alone is a strong hint that may something important may be going on here."
That is exactly what we have been discussing isn't it Passerby?

Make sure you understand where you're pointing, to, RR.

en.wikipedia.org/wiki/HerÃ°ubreiÃ°
en.vedur.is/earthquakes-and-volcanism/earthquakes/vatnajokull/

We were talking about the clustering under Vatnajokull, NW corner. You're now referring to a fracture zone to the north of the icecap.

If an increase (above interannual average) in geothermal activity under the icecap results in a large lake forming, which is released as a sudden flood, it's possible that volcanic centers (probably Grimsvotn) will be destabilized at either crater or associated fissures and would then erupt. Whether the force of an eruption would be enough to break through 700-900 feet of ice and throw up a large volume of ash, is not known. IES can better address this question.

#37 @Passerby: Yes, I know HerÃ°ubreiÃ° is far to the North of Vatna, but I thought it could be somehow involved in the whole fracture system. But as I see, I am wrong at this.

>That is exactly what we have been discussing isn't it Passerby?

We've discussed interplate EQs, faulting and rifting at sites like Reelfoot Lake/New Madrid fault in the south central US, and to a limited extent, faulting along the Wasatch Front and SW corner of Utah (wrt geothermal activity), but we haven't gone much into intraplate tectonics.

This quote from the same source:
The plume hypothesis as it is applied today requires that Earth dynamics is driven by two independent modes of convection - plate tectonics and plumes. The former is driven by forces at plate boundaries - ridge push and slab pull, and the other is driven by heat from the Earth's core.

is a bit oversimplifed and outdated. That's why I posted a more recent paper written and published a few years ago.

The latter (plumes), especially the mid-depth yellow dots on Courtillot's figure (plumes originating from the depths of the upper mantle) may be a case of intact, less dense folded crust rising with heating from pressure change and mixing chemistry, after passing under thickened continental boundary.

The action of subduction and plume, at least in in the Yellowstone case, does not appear to be 'unrelated'.

What Chris doesn't mention, at Highly Allochthanous, is that there is a physical and very long transverse fault system (with respect to the coast) that roughly parallels (to the south) the A-A' transect shown in Fig 2 of his Yellowstone plume blog post. That's a clue to the curving coastal plate subduction driving the curving torsion, shown in Fig 1.

@38, we have more or less parallel track grouping of EQ activity, but having different mechanisms, as discussed in a couple of nifty papers with referenced figures described here, which Lurking then used to superimpose recent seismic activity for reference, and he also graphed their frequency over time.

#39 When we were discussing the Moro Golf deep focus quakes it was suggested that they have to do with "invisible" subducted plates and related faults, which I understood could be pretty much the same source of meltings under Yellowstone. I apologize for my skipping to conclusions too quickly, and maybe William is right when he tells me to read all those books before I post my opinion (even though he says he was joking). So please feel free to correct me and tell me when I should be quiet. I'm really happy to hear what you guys have to say, but so far I'm convinced that maybe other people could benefit from the wisdom with which you respond to my stupid remarks (yet I could be wrong on this too).

#40 Certainly missed this discussion. My fault.
What intrigues me most is this repeated pattern of swarms (or isolated quakes) occurring almost simultaneously all across Iceland, like over this past 4 hours report from IMO: Reykjanes + Vatna + HerÃ°ubreiÃ° + Askja + TjÃ¶rnes. Difficult to think they are not somehow related (beyond MAR).

Mount Sinabung in Indonesia seems to have had a small eruption today.

If you go to Chris's blog, which started us looking at deep focus earthquakes and possible mechanisms,

all-geo.org/highlyallochthonous/2010/07/fridayish-focal-mechanisms/

He correctly describes the opening sequence of deep focus EQ, that continued for quite a while, as being related

>All four focal mechanisms indicate NW-SE extension. Like the Halmera earthquake, this sequence appears to be linked to the westward subduction of the Philippine plate beneath the Sunda plate, with the earthquakes taking place in a deeply subducted part of the Philippine slab. The extension is probably the result of down dip tension as the slab sinks into the mantle, with the first shock apparently triggering similar events above and below it.

But that only whetted our appetite to know why they are occurring at such depth. While it could be stretching and elongation, the fact that they tend to cluster at specific depths was shown by Lurking in his graph and more obviously, in USGS and PHIVOLCs EQ data that we picked up from a secondary source and couple of related papers.

That made us wonder about the potential for *structure*, because these same critical depths of clustering were found in other places, like near the Cocos plate.

That led to set of references that have, for me, been exciting to read and ponder. For instance, Dr. Courtillot's plume and tectonics map

http://www.geolsoc.org.uk/webdav/site/GSL/shared/images/ourviews/plumes…

shows two shallow hot spots, to the east of the subducting Cocos plate, off the coast of Southern Mexico. That could be rising heated and unfolding subducted plate (pleated) that doesn't have the overriding thick continental edge to contend with, so buoyancy, heating convective forces drive it up from shallower depths. Maybe.

Your questions and remarks are never stupid.

Alternate theories - And then there was three.

geology.about.com/od/platetectonics/a/nohotspots.htm

What we are talking about here, and technical discussions of a few recent papers seem to be pointing to this conclusion, is a third theory: that thinned and subducted plate material sinks into the depths of the upper mantle, much deeper than 400 Km when it's very cold, water-laden ocean material, and is pushed deeply under continental crust, where it, amazingly, remains intact for some distance underneath the lithosphere.

A volcano on Sumatra, named Mount Sinabung stared erupting today at 19:00 GMT (midnight local time). According to news, this is the first eruption in that volcano for 400 years.

Here is the BBC News on this eruption.

www.bbc.co.uk/news/world-asia-pacific-11123169

Here is the volcano information. But that has last eruption listed as unknown.

www.volcano.si.edu/world/volcano.cfm?vnum=0601-08=

Wiki article.

en.wikipedia.org/wiki/Sinabung

Here's a link to the Jakarta Post

http://www.thejakartapost.com/news/2010/08/28/agency-says-mt-sinabung-i…

Solfataric activity with incandescence 1912, no eruption. Last eruption listed by as 1600AD.

www.thejakartapost.com/news/2010/08/29/volcanic-ash-clouds-blanket-meda…

See other related articles, side bar.

Etna popped again

http://i36.tinypic.com/301253n.jpg

#43 Your last flattering remarks will have me popping up again. Thank you for the incentive, Passerby.
And now, lets learn what is going on in Sumatra.
Thank you for the info, JÃ³n.
And thanks for the update on Etna, Raving.

@Passerby

The statement in nohotspots.htm:

"Seismic imaging around some major, classic hotspots has not found clear evidence of magma conduits below the transition zone (400 to 660 km deep). At the Yellowstone hotspot, Humphreys' team found that the transition zone is cool, not hot."

Seems to be contradicted by the "figure 2" image (right hand side) at all-geo.org/highlyallochthonous/2010/08/yellowstone-what-lies-beneath/

But my real question, if you don't mind:

"...That's a clue to the curving coastal plate subduction driving the curving torsion, shown in Fig 1."

Then what causes the apparent curve? I would think that whatever feature that it cause would trend south ward since the southern edge would be leading the charge. That is unless it separated unevenly.

(Note, I'm not sure where the figure 1 is at, I am assuming it's the image above the labeled "figure 2")

Is it a shearing of the two sides of what once was a spreading center for the Farallon?

You also mention

physical and very long transverse fault system (with respect to the coast) that roughly parallels (to the south) the A-A' transect

Is this a surface feature or a deeper item? If the latter, is it associated with the leftover part of was the spreading center?

According to the 3D model on Wikipedia, the Farallon currently resides deep under the East Coast. You don't happen to think that what is under Yellowstone / Snake River is the left over western part of the Farallon? Sort of the left behind part, all folded up and shoved down into the muck.

Sinabung Simatra erupts after 400 years:
http://www.reuters.com/article/idUSTRE67S06O20100829

Reuters says 'first eruption in 400 years" -I'd guess they mean "First eruption in at least 400 years" since that's about the length of the historical record there. GVP profile says no confirmed dated eruptions (one uncertain in 1881)

Some of the very first pistures of the eruption on an Indonesian News Site: http://www.google.de/imgres?imgurl=http://www.detiknews.com/images/cont…

@42 (Renato Rio)):

As you know I once sugested that there is a force running all those formations, and that those separate formations where taking there force from one central source of power.
My theory might be glaringly wrong since I am not a geaologist, but mathematically the theory is sound and corroborates with at least some of the evidence witnessed in the simultaneus events we can all see.
About my theory, the basis for my initial thought was to look for inital causes of that part of the world. Because I think we can all agree that something is lacking in the standard modell, my theory might be entirely wrong, but someone has to come up with a theory in the end to fill up the missing parts sooner or later.
And let me remind you that almost all of todays theoris are just theoris. One should always challenge them now and then, even if it is done from someone who is wildly out of his field of expertise. In my case my knowledge of geology is to low (but I do have some and gaining more every day), but my knowledge in physics in general and fluid dynamics in particular is good. If I ever gain enough knowledge about geology I will probably sumarize it into a paper, mostly out of the math being really neat.

What I really would like, is to see an original thought from Passerby on the subject.

Sinabung in North Sumatra is quite close to Toba. It's located close to the town of Berastagi. There is an adjacent Volcano - Sibayak which overshadows the township itself. The two Volcanos maybe plumbing related. Berastagi is an important vegetable and fruit growing area. Its located on a plateau around 1000 metres above sea level - The temperature there is very pleasant.
Here are some images.

This is Sinabung. Note that there have been sulpheric emissions for hundreds of years.

http://farm5.static.flickr.com/4137/4936892099_f79266dfc5.jpg

http://farm5.static.flickr.com/4137/4937478340_2a29d57077.jpg

Here's its sister Sibayak

http://farm5.static.flickr.com/4120/4937478424_6ceb00b489_b.jpg

More about Sinabung.

http://news.xinhuanet.com/english2010/world/2010-08/29/c_13467877.htm

Good morning, evening, night. Here's more info on Mt. Sinabung. There are more links at the bottom of the story. If you go to the front page of the post, there's a dawn/dusk pic of the eruption that looks pretty impressive.

www.thejakartapost.com/news/2010/08/29/a-safer-place.html

Video of Mt. Sinabung

www.youtube.com/watch?v=7jx_ZQ9848g&feature=player_embedded#!

#52 @Carl on Iceland:
It's not only the swarms recurrence, but also tremor plots and GPS measurements that show parallel fluctuations, even though kept within standard levels. I can't tell what causes these fluctuations, but just speculate if there could be some sort of common source for them all. Looking forward to hear more from you.
@everyone on Sinabung: Another next VE3 candidate? After 400 years you don't know what to expect. According to linked news there have already been two deaths. Worrisome.

Some news on Sinabung:

http://scienceblogs.com/eruptions/2010/08/new_eruption_at_sinabung_in_i…

For anyone interested in the 1883 Krakatau eruption the fascinating Royal Society report from 1888 is downloadable (PDF 27.2 Mb):

http://ia311311.us.archive.org/1/items/eruptionkrakato00whipgoog/erupti…

I love this game, this is a great article bring back some memory.

I saw something about this topic on TV last night. Nice post.

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A busy day for Etna and Galeras

eklemetti — Wed, 25 Aug 2010 11:18:12 +0000

A busy day for Etna and Galeras

Today was a doubleheader for volcanic eruptions in the news:

Today's explosive eruption from Mt. Etna. Image courtesy of the INGV.

As I briefly mentioned earlier, Galeras in Colombia had an "atypical" eruption - apparently meaning it was non-explosive - that has prompted evacuations and a change in the alert status to "Red" for the volcano. Various news sources don't have a lot of new information yet, but you can check on the report on the INGEOMINAS page (spanish) - and they have links to some of the Galeras news (audio, spanish) from their main page. Some of the latest reports from Colombia (spanish) indicate that the eruption is "ongoing" but "under control" and areas around the volcano are experiencing some ash fall. However, Diego Gomez of the Volcano Observatory in Pasto is calling Galeras a "very unstable volcanic system" right now, so we'll keep an close watch on the volcano - which you can do from the webcam.
Less than a week after Boris Behncke's great series on the volcano, Italy's Etna has decided to keep our attention by having an explosive eruption earlier today. The INGV already has a great post on the event (italian and english) on their website with pictures and thermal images of the ash-rich explosion that produced the 1-km tall plume. This is the largest explosive event this summer from the Bocca Nuova ("New Mouth?") vent. Again, if Etna is heading into a new eruptive cycle, we'll all want to watch the events unfold - and luckily there is a webcam for that as well.

For both of these events, updates as they arrive!

{Special thanks to all the Eruptions readers who have posted links/info.}

eklemetti Wed, 08/25/2010 - 07:18

Tags

Note that the update on the INGV-Catania website is both in Italian AND English! I somehow didn't manage to make an English version of the title; next time I guess I will create two separate files.
By the way, some ash has fallen on our house in Trecastagni, about 15 km southeast of the summit of Etna. First time in 3 years that we've had ash from Etna at home.

Thanks for pointing that out - I just sort of muddled through it and didn't even notice the English on the bottom!

Keep us posted on any new developments!

In other news an interesting news release from USGS:

"An Island's Rebirth: Life emerges After a Catastrophic Volcanic Eruption"
http://www.usgs.gov/newsroom/article.asp?ID=2574

Boris, it might be prudent to re-engineer the INGV website so that it presents in several languages, including English.

It will do wonders for attracting international interest and support. As it stands now, it's not very user friendly to those who don't read Italian.

@Boris Behncke, Catania, Italy, Do you have any online webcorders that I can take a look at ? I think that there might be more to this explosion at Etna then meets the eye.

I am also considering moving to Sicily in few years time (after few years living in Denmark) to watch and monitor Etna eruptions.

Or better yet, public real-time waveform data, USGS-style.
Ok, that's hoping too much maybe :)

@Passerby #4, I am working on an English version of the site - since I am the one single person in charge of this, it takes a bit of time, but all updates from now on will be in Italian/English (let's hope there will not be too much to update on, for the moment, since I still have to do my summer holidays).
@JÃ³n FrÃmann #5, that would be a fabulous thing to have you here and look at our seismic data ... unfortunately all that can be rendered public is what is actually rendered public (we've got to treat a lot of data confidentially due to Civil Defense issues), but once you're here things will be easier.
What is important to point out is that today's event seems to have been phreatomagmatic, and such events are among our worst nightmares, because very often they have extremely little precursory seismic or other activity. In 1979, nine tourists were killed at the very same crater that made today's explosion by a similar, though more powerful event. What is true is that since a few weeks we've seen a series of smaller explosive events (and collapse) in the Bocca Nuova, especially on 5 July and on 8 August. Normally such explosions occur when magma rises in the conduit and encounters fluids, and my best bet is that sometime within the next few days, or weeks, or maybe months, we will see new magma appear within the Bocca Nuova, as happened also in the summer of 1995 after more than 2 years of quiescence. There are frequent explosions also within the Northeast Crater, which is another of the four summit craters. These explosions are still very deep and you will not see any material being thrown out because it is happening presumably at a few hundred meters of depth. But you do hear these explosions when on the rim of the crater, and they appear to be growing in frequency and strength.
So the signs are that magma is rising within the conduits leading up to the summit craters, and hopefully we will see some spectacular activity there before a new flank eruption will rip open one side of the mountain and stress the hell out of us and everybody else involved.

I have posted some photos on my Flickr page: www.flickr.com/photos/etnaboris

Ok. I must go to work now, just passing by to ask if you see some activity on the right slope of the Galeras cam. The ash cloud is getting bigger, hovering over the village, to the left, but the funny dark cloud to the right, looks weird. Regular clouds?

@Boris #7: seismic data is considered 'confidential' due to 'civil defence issues'?!

The mind boggles. The word 'idiots' comes to mind. That sounds positively Soviet...

Care to enlarge?

Sheesh, 2 minutes warning on the Etna seismometers (a posteriori) !

@Boris Behncke, Catania, Italy, As the eruption in EyjafjallajÃ¶kull showed. I can detect a low harmonic tremor from up to ~40 km away (maybe more, but more distance less signal is always the case). Where I go, I take my geophone with me and I do put them online since I am not bound to any contract like you. I do not like the signatures in the plots on the pictures, they indicate a gas-pressure pocket inside the volcano. I do not know where inside the volcano it might be.

If I move there, I will be there sometimes after 2015. I will let you know when the time comes. :)

Ref [9] (Fireman)

I'm guessing it has a lot to do with panic and lawsuits.

With the way that the Icelandic and Cascade volcanos show up in the seismic data, I was thinking that after that awesome plate outline that Galeras would give this beautiful seismic stack.

I was disappointed. I'm guessing that that the volcanic stuff doesn't make it into the database.

http://i36.tinypic.com/30wbldv.png

This Emergency and Disaster information site is not up-to-date with Mt. Etna's activity (last Etna page update was June 1), but the map shows activity. Their earthquake listings include whether or not a quake is located near a volcano. I think that's a new feature. The "Supervolcanoes Monitoring System" has quite a long list of calderas and other massive volcanoes.
http://hisz.rsoe.hu/alertmap/index2.php

Good background material, with some answers for you, Lurking.

THREE-DIMENSIONAL SPATIAL DISTRIBUTION OF SCATTERERS IN GALERAS Volcano (book chapter).

www.tdr.cesca.es/TESIS_URL/AVAILABLE/TDX-0905106-125920//Carrube6de7.pdf

Scatterers are the signals used to determine magmetic structure placement below the volcano.

This article explains why you have such a busy shallow EQ system (says same thing as chapter, above, but more succinctly).

1989â1995 Earthquake sequences in the Galeras volcano region, SW Colombia, and possible volcanoâearthquake interactions. Tectonophysics 2008

>The area is also affected by the continental faulting represented by the Buesaco, Aranda and Pasto faults belonging to one of the most seismically active structures in Colombia, the Romeral fault system.

and

>The coexistence of an active volcanic complex and an active fault system complicates the study and interpretation of the different processes taking place in the region as well as the identification of any connection or interaction among them.

Conclusions:

1. You may not have access to all of the seismic data for volcanic EQ and

2. The superimposition of tectonic and volcanic seismic activity complicates sorting signal origin/cause.

Might explain the hash of data, rather than a clear signal source below the volcano.

I sort of figured that there was missing data from the catalog. As for the two "platforms" of quakes... I'm thinking that's and instrumental artifact and not part of what is actually going on there.

As for the paper, good read. Any idea how they came up with the idea of "screw" to describe the shallow low frequency events? (tornillo)

Dunno if it implies a shaking or a shape.

The Coda Wave idea is new to me, but I like the idea of the seismo/geo people getting into interferometry to sort of peer into the depths of the volcano's feed system.

Google Tranlate does a good job of translating Boris's website into English. The left side menu is nicely translated also. Just save the link as a favorite.

http://translate.google.com/translate?hl=en&sl=auto&tl=en&u=http%3A%2F%…

Or Boris could have the link on the front page within a buttton called "English" - and just letting Google Translate do all the work, lol.

Could use the same trick to have buttons to translate into any languages.

William M Boston

@Passerby
Trying to do my homework on Galeras, just stumbled into this on page 118 in the article you posted (thanks for it):
"Such lava tends to be high in silica (mafic magma)."
I suppose it should be the other way around mafic=low silica felsic=high silica. Or maybe I'm wrong?

@ 16. Yeah, sure you can use Google for a hashed version in English (or French or Spanish or German), but it won't bring in non-natives, and it won't build you a fan club and *lots* of tourism revenues that can be translated to supporting geology and civil defense.

That's why the IES and IMO were clever to be as forthcoming as possible in sharing and explaining technical info in updates and graphics with the rest of us outside of Iceland (in English), and I suspect, to encourage realtime webcam coverage.

It's got them a nice dividend in tourism economy, despite the negative press from passenger air traffic shutdown for several weeks in May.

Etna is, as Lurking put it, a huge mother of a volcano. It's sheer height, longterm activity and explosive power, in a heavily populated region, is rarely matched in terms of potential for impact especially when viewed in terms of combined action it's active neighbors to the north.

@Lurking #12

Why is there a line of quakes at 4.5 km in the plot you made, as shown in link following?
http://i36.tinypic.com/30wbldv.png

I see the same thing at Yellowstone at almost 5 km and sometimes faintly at nearly 10 km, as shown:
http://yellowstonecaldera.net/Yellowstone/quakes.php?from_mo=8&from_dy=…

I'm sure it must be for some well known reason. But I am not sure what that is.

Lurking? Anyone?

At Renato, standard boiler plate

Basaltic magma is made up of mostly mafic minerals. Rhyolitic magma has high levels of felsic minerals. Andesitic magma is composed of intermediate minerals -- not quite mafic, not quite felsic, or a fairly even mixture of mafic and felsic minerals.

Mafic magma (basaltic magma) will have a fairly low viscosity and is associated with shield volcanoes (Mauna Kea for example), and mid ocean spreading centers.

Felsic magma (rhyolitic magma) is much more viscous and is associated with explosive volcanic eruptions found in Composite volcanoes (also called Stratovolcanoes).

Andean volcanoes are predominantly andesic and dacites. See wikipages for Galeras, andesite.

Geochemistry and petrology of the Galeras Volcanic Complex, Colombia . J. Volcanology Geothermal Res. 77 (1-4):21-38 (1997).

>The Galeras Volcanic Complex (GVC) has erupted lavas and pyroclastic flows, ranging from basaltic (mafic) andesites to dacites (more viscous), during the last million years.

Wording is somewhat confusing. More attention should be paid to the volcanic earthquakes, regional faulting, and magma chambers inferred by seismic 'reflection'.

For Lurking, 15: see

seismo.berkeley.edu/annual_report/ar03_04/node20.html

Refers to seismic record (decay events, signal tailing, coda), not physical manifestation of EQs forming an ascending screw-shape.

Off topic, but I didn't know where else to put it.

FYI. This is a new theory on the formation of the Earth;

Evidence supporting Kevin Mansfield's Earth Formation Hypothesis.

The Hypothesis:

Earth, as we now know it, formed from the collision of two similarly sized planets, called Heaven and PreEarth. Heaven had a radius about ninety percent that of PreEarth. These two, initially comprised a binary system (just like the Earth and Moon presently comprise a binary system) orbiting the Sun.

Like a bullet rips through the skin of an apple, leaving most of the skin unscathed, Heaven crashed through the crust of PreEarth, taking most of its energy into the interior, while leaving much of the crust unscathed. Now, imagine that the mass of the apple and bullet are so large (planet sized) that the bullet cannot escape their combined gravity. Then you have the hypothesized situation. Of course, as PreEarth swallowed Heaven, it greatly expanded in size. This expansion, however, did not leave the remaining crust unscathed.

The Evidence:

1) The hole in the Earth where the planet Heaven entered, i.e., the north west Pacific.
2) The impact mountains around the Pacific Ocean, i.e., the ring of fire.
3) Western impact mountains ripped off continental block.
4) The impact caused continental drift.
5) The theory predicts a single circular continent with splits, i.e., Pangaea.
6) The theory predicts oceanic crust very different from continental crust.
7) Warren Carey's evidence, is also evidence for this hypothesis.
8) Apparent sea-floor ages explained as geochemical gradient due to mixing.
9) The theory predicts Earth's core is rotating faster than its mantle.
10) The theory predicts Earth's magnetic field is rapidly decreasing.
11) The theory predicts/explains magnetic reversals.
12) The theory allows the force of gravity to have been smaller in the past.
13) Removes the thermal catastrophe.
14) The theory provides a decent power source for continental drift.
15) Animations of the expansion plus drift can be produced.
16) Provides a new theory regarding the formation of the Moon.

See http://preearth.net/evidence.html where each point above is expanded upon:

A brief history of the ideas.

Many of the ideas above were first presented in a public lecture, on November 2, 2008, at the Alexandra Park Raceway, Auckland, New Zealand. They were subsequently written up and published, on April 20, 2010, in the form of a 26 page paper. The preprint server arxiv.org refused to distribute this paper (clearly, the task of releasing preprints to the scientific community should be taken from those at arxiv.org and given to some responsible party). Consequently, toward the end of May, the website www.preearth.net was established to publicize the paper. This summary of evidence was completed on July 29, 2010.

Kevin Mansfield, has a BSc(Hons) from the University of Auckland (Auckland, New Zealand) and a PhD in mathematics from the University of New South Wales (Sydney, Australia).

From http://preearth.net

The site http://hisz.rsoe.hu/alertmap/index2.php claims also Stromboli is erupting?

@William M Boston[19]

Honestly, I don't know. Having worked with instrumentation, my gut feel is resolution error. If the signal from a quake has much ambiguity you will get only as fine a target as can be determined from the gear. You will especially see this in any of my plots that use data that crosses several years of technology improvements. A a rough guide, the most recent 5 to 6 years of data can be (sort of) assumed to have the quality of modern equipment. But you have to be careful with assumptions. (that's based on what I've seen in my plots)

Also remember that I only have access to the data that is publicly available, and cannot do any independent Q&A of what is in the databases. (not a researcher either) I generally count the oddities like that as "instrumentation" or "technology" errors.

@Passerby...

That rocks.

So the tornillo is actually the coda waveform itself and is a separate class of waveform... not a quake, and not a harmonic tremor. Sort of a "ringing" of the subsurface structures as seismic waves pass through or bounce off of them. The "scatterers." As previously mentioned.

From one of the other links I was left with the notion that it was something they were just snagging off of the waveforms for arbitrary quakes around the volcano.

That is very cool.

For those who are asleep I can just say that the daytime imagery from Etna is spectacular with nice strombolian activity and a lavarun downslope (Upper-left) if I am understanding the imagery correct from the webcam.
I think Boris summer vacation got cut short on this one.

http://www.guide-etna.com/webcam/wcsrc/wc3.htm

Anybody with more webcam links out there.
Seems like it is time to sit in the vibrating volcano-chair again and drink beer and watch lava-eruptions.
Good thing = The weather is better for webcaming at Etna.
Bad thing = more people around Etna than Eyja.

Here is a better link with more cams.

It seems like the scineceblogs-goblin had a problem with the last attempt to post it so it is without the http and www...

guide-etna.com/webcam

Hello,
Images of Galeras. Unable to see the official site
http://www.facebook.com/album.php?aid=23797&id=129540827071058

@Boris:

Two small questions, both probably silly.

1. Is it just Bocca Nuovo erupting, or is it Bocca Nuovo and North Crater?
2. What is the likelyhood of Catania being hit by the eruption? Should I fly down and move my boat from Catania?

Totally understand if you don't have time to answer.

Best of luck with your continued work with Etna, and your wonderfull articles where ominious and fortitious for us volcanophiles:)

Carl

I'm surpised that sites with web cams do not have scripts which combine a number of past images, say 10, as an animated gif file, which would of course then be updated at the same interval as the webcam (say about every 60 seconds).

Then on the same otherwise boring web cam page, people could amuse themselves endlessly by clicking on the continuously updated timelapse gif animations (say for last 10 minutes, last 30 minutes, last hour). Gif animations are trival to create from image files, so it should be easy to program for automated creation.

Timelapse animations of oldfathful and all the people movements would be interesting and great amusement. And convenient to click a timelapse animation of the last hour to quickly check for a geyser display.

And right now that Etna action with fire shooting up in the air on CAM 3 would be great as an timelapse animation.

Off-topic: If you have to go on geology excursions into the dry, fire-prone forests, here is a bit of good news:
"Fuel treatments reduce wildfire severity, tree mortality in Washington forests" http://www.physorg.com/news201979329.html
In other words, if the authorities do a minimum of prevention, neither geology students nor others need to get burned to a crisp.

Hi,
Boris postet this link to some real-time seismic data in his Flickr feed: http://193.206.223.22/Etna2007/SegSismici.asp?Staz=ESVO_HHZ_IT&Pos=6

Original entry can be found here: www.flickr.com/photos/etnaboris/4928165941/

Etna on cam 3 is showing increased intensity. The fire is shooting higher on the left side, and recently it has begun to shoot explosively in the air on the right side also.

I believe the left side is the so called side vent, whereas the right side is the location of the three main craters on the summit. But not sure about that. Anyone know?

Correction to earlier comment about fire shooting into the air at Etna ... it is probably just steam ansd smoke but with the appearance of fire due to the intense side lighting of the morning sun, and to its being washed out as a result of the saturation of the cam's sensors.

The display has showed increased intensity. Was originally just on the left side, but is now occuring on the right side now also, as viewed from cam 3 .

I believe the left side is the so called side vent, whereas the right side is the location of the three main craters on the summit. But not sure about that. Anyone know?

Hi,

What is going on at Eyja? The Mila webcams show a imho big plume above her.

and to others who check in on Iceland, news of maybe more reasons for seismic effects that we've been noticing - glacial unloading has already been mentioned, now it's in the Icelandic news...tho' not extrapolated to volcanics.
www.icelandreview.com/icelandreview/daily_news/?cat_id=75139&ew_0_a_id=…

@William:
The left vent is the Southeast crater, on the right Northeast crater and on the saddle between those two, Bocca Nuova (left) and Central crater (right), seen from Cam 3. It looks as if all four craters are steaming violently. And there is a small vent steaming on the slope on the left, which was also steaming when I was there in July.

@35 Peter Which number three? Etnaguide or the INGV one (altho' I've just notice #3 is down-- oh well, another reference--

http://www.ct.ingv.it/index.php?option=com_wrapper&view=wrapper&Itemid=…

@36 parclair NoCal
Sorry, forgot to mention: webcam 3
http://www.guide-etna.com/webcam/

I do not like the low period earthquakes on the INGV sensors around Etna. Those earthquakes appear clearly on ESVO seismometer that INGV has.

@JÃ³n FrÃmann

Out of curiosity, other than location information, is there anything that can be gathered out of the leading or lagging of the various signals from ESVO vs ESPC? I realize that they are pretty much on opposite sides of Etna and ESPC seems to lag by as much as 3 seconds in some instances.

Stacked plot of the two, ESVO on the top trace.

http://i34.tinypic.com/5mgwzk.png

Sorry been out all day without access to any computers.

There is currently no eruption of incandescent magmatic material under way at Etna. There have been a few more, but smaller, explosions, from the Bocca Nuova last night. No large rocks have been ejected, just ash, and the material appears to be a lot of old, altered rock with maybe a minor fraction of new magmatic material.

@JÃ³n FrÃmann, the signals that you see on the ESVO seismograms are explosion signals, caused by the deep explosions within the Northeast Crater. These have been occurring, though less frequently and less strongly, for many months. It is a very typical sign of Strombolian activity. But certainly the gradual increase indicates that magma may be rising within the conduit of the Northeast Crater. This is, so to say, Etna's most typical business.

@Carl on Etna #28, the latest explosions were from the Bocca Nuova, but the Northeast Crater has continous deep explosions since a while.
Catania has never, not one single time, been destroyed completely by lava flows. It has been threatened on a number of occasions, and its western outskirts were destroyed in 1669, but not its center. Today it would be far more difficult for a lava flow to reach the center of the town and the harbor, because of the multitude of multistorey buildings in reinforced concrete that constitute Catania's suburbs. These would provide a serious obstacle for a lava flow, which cannot be simply overrun or broken down by a lava flow.

In any case there are no signs that at Etna a major destructive eruption is imminent (that would mean, a flank eruption from low elevation). What I consider the most likely scenario is that in the next few weeks to months we will see a gradual reactivation of the summit craters, and then for some time - which may be months to years - summit eruptions, which are the most beautiful thing one can imagine, and they are not a threat to populated areas and human property. They might occasionally disrupt air traffic, because they can release significant quantities of ash.

Then, as more magma usually rises into the volcano's feeder system than exits from its summit craters, the mountain will gradually swell and become more unstable, and this will be recognized by the seismic activity and by the deformation monitoring, as well as gas emissions. In case of a major flank eruption - especially one from low on the flanks - there will possibly many weeks of premonitory deformation and seismicity, as was the case before the last eruption of this kind, in 1669.

The worst scenario we're imagining is a flank eruption that develops extremely fast and emits lava at very high rates, as in 1981, when lava initially travelled at a speed of 3 km per hour - and the nearest population centers were 7 km away. Luckily in that case the lava passed between two villages. That was on the sparsely populated northwest side of Etna, near the town of Randazzo. An eruption of this type on the very densely populated southeast side would be an enormous challenge.

Funny anyway how I just posted that big Etna story one week ago and now the volcano is getting a bit more active.

I will keep you informed ...

EyjafjÃ¶ll has a nice big plume today ..

I guess thats only water from the crater that has made its way inside the crater..

it looks nice tough in the sunlight..

@Boris Behncke, Catania, Italy. I am going to send you a email this weekend with few questions. Since if I am going to move close to Etna volcano in Italy. I have few questions to ask and to be answered if possible.

I am considering skipping Denmark all together and go directly to Sicily, Italy.

I have been trying to read your data. But I don't have a lot to work on. But I do believe that the magma that is pushing up the volcano is moving faster that you currently think. But with the data shortage that I am dealing with, I might be wrong. Only time is going to tell me what happens next.

Here is a capture of a frame from web cam 3 earlier today. http://i38.tinypic.com/vp8fx1.jpg From that angle and with that sunlight angle, the steam can easily be confused with fire shooting up from Etna's craters. But no fire ... yet.

Here is a quickie gif animation I made from of 12 frames from the web cam.

http://i35.tinypic.com/xpps9j.gif

Notice also the venting from the lower ridge on the left.

Curiously, the vid cam (#3) refreshes the screen every 20 seconds, but only refreshes with a new image every 2:40 seconds. I wonder if that is by design or by malfunction. About 3 minutes between images seems unusually long. Due to the long image display interval, there isn't much continuity between the frames.

Anyway, web cams create image frames perfectly matched to frames required for timelapse animations, and, as mentioned above, it would be so useful, interesting and esay to have such timelapse gif files automatically created for viewing directly from the webcam's page. Such a shame not to implement that.

Ha ha .. This awesome song comes to mind when viewing cam 3.
http://www.youtube.com/watch?v=flOvM4Z355A&feature=related

All devotees of Etna should play that song for her! A great song, and so fitting for Etna at this time! When you listen carefully, you can hear harmonic tremor! ;)

And soon Enta and her devotees should play this equally great classic song for the molten lava struggling within her. So appropriate for the moment! ...
http://www.youtube.com/watch?v=CbiPDSxFgd8

Here is a quickie gif animation I made from of 12 frames from the web cam.

http://i35.tinypic.com/xpps9j.gif

Notice also the venting from the lower ridge on the left.

@Peter Tibben re #35

Thanks for the description. Let's see if I can correlate that with the following Google Earth pic:

http://i35.tinypic.com/rad83l.jpg

My favorite view of the summit craters, as in the pic above, is upside down with respect to cam 3's view, but I have it imaged correctly now in my mind for that perspective. :)

@William M Boston:
Thanks for the *gif time lapse. And I agree it would be a good idea to have them at the websites.

AVO raised Cleveland to yellow due to a 'persistent thermal anomaly'

@44 William M Boston
Thanks for the time lapse gif. For comparison, see picture
http://picasaweb.google.com/ptibben/EtnaSicily#5507022110941199874 which I took on July 17. The steaming east vent of Southeast crater on the left and right from the centre, on the slope, is the small vent (yellow sulphur deposit)on your time lapse gif.
Boris has some nice aerial pictures of the topcraters on his flickr page http://www.flickr.com/photos/etnaboris/page21/

I just came up with a rather perverted idea...

I was leafing through pictures of Etna and suddenly it dawned on me that it would be perfect to build a house inside one of the 300 smaller craters. If I understand it correctly they just blow once. But I guess there is a law or fifteen against doing it. But oh my... wouldn't it be beautiful to live in a crater when the volcano goes:)

You can see what I am talking about in the third picture from the top in this link, I say "dibs" on the one in the middle (imagine a concrete walled in castle with a watch-tower with decking around a cool beer and...)

@Carl, living on a volcano would be fine *except* for the sulfur in the air. Kinda takes away from the pleasure... (sulfurous beer, yech) ;-)

I wonder how high the sulphur concentration in the air is about that spot?
I don't think it is that noticable except when Etna is blowing hard. And to be honest I could stand some sulphur in my bear to watch Etna Bopp from an observation tower. But my original plan was to have the tower glased in and the entire compounds air running on an air-purifier/degasser in a presurrised setting. I don't want to get totally gased if the wind is wrong. But around the plattform there should definitly be som decking so one could sit outside schmoozing a bear when the wind is blowing gasses away:)

@Boris:

Let's rephrase the craterhouse discussion into silly question number three and four for Boris:
3. How high would the concentrations be of Sulphur and other poisonous gasses around those smal 300 craters? Is it still breathable?
4. Is it a ban against building a house there? I could as well just build a house there to go along with the boat I allready have there. (If your around the port someday it is the vintage 50 fot Alden that is currently being repainted thanks to the good crafts-men in Catania.

Carl, Is it really worth the feeling (to be watching Etna go up in a major way) to be telling about it to St. Peter at Heaven's Gate? ;o)

@Jack:
Actually I think I've done something worse...
31 August 2004 I was sailing like a madman to get south of the Virgin Islands to avoid Frances to no great luck. Volcanos might be passably dangerous, but I would take them any day to a category four hurricane. Sitting on 17 ton boat that gets airborne is as close as I ever want to come to St Peter and his merry Wallruses.

@Carl
(LOL) I'd rather have my beer in a pub next door. :)

Some news on the steam rising from EyjafjallajÃ¶kull: http://icelandreview.com/icelandreview/daily_news/?cat_id=16539&ew_0_a_…

@53 try riding a aircraft carrier in a hurricane and taking green water over the bow, early 70's

@56

Done it in a Frigate... does that count? I know it's not as but but we buried the gun mount in green water, which then smacked the bridge.

I would not like being on a carrier if green water hit the bridge. it is a rather interesting experience not knowing if the boat is going to auger it's way to the bottom or come back up

@56:
I would prefer to be indoors on a carrier then being tied to the rudder-wheel housing outdoors on a fifty fot sailing yacht any day to be honest.
The sheeting of water from the waves (it is no longer mere spray in a 4) travelling at 125 knots have a tendency to give you a rather nice skin peel, but it hurts like hell.
Plus that it solves the problem of having to go to the mens room, you are generally so scared that you just solve it by pooping in your pants. But I guess I am a wuzz:)
For those wondering what the name is of the sail you use in a hurricane, it is called a storm monkey. Mine was one square-metre and it still sufficed to give me 9 knots of continuous speed.

But... If you do it correctly you can hike the stern on a wave-front and just happily surf for the next twelve hours with your eyes riveted backwards up the 20 metre greybeard behind you, after a couple of hours you will probably be speaking to it since it feels like an old friend, I even named "my" wave Herman after Herman Melville.
Good thing was that nobody even cared about me entering the US. I guess the Coast Guard and US Customs had better things to do.

So please give me a lot of land in a crater adjacent to Etna.

gina ct 56: You know you're in trouble when the Captain comes up and tells you that your transfer to submarines has been successful :o)

@Carl #48 and following - no problem with the gas at Etna except if you're right at the summit on the downwind side. There is no gas emission from any of the craters on the flanks (except those formed in 2001, 2002-2003, and 2008-2009, which will remain hot still for a few years to come). There are areas of diffuse carbon dioxide emission especially in the valleys above the town of Zafferana, but those areas are now well known and are not open to development (construction, agriculture).

Many of the cones and craters on the sides of Etna are already private property - but most of them are on the territory of the Etna Natural Park, where construction is either totally prohibited or allowed only in a very rudimentary way. So I would rather propose some place lying on a ridge or on a hill rather than in a valley - unfortunately in recent years much development has taken place in valleys, and these are at high risk from lava flow invasion during future eruptions. So those areas are no-no for anybody interested in moving to Etna.

I do actually like a lot sitting on my terrace watching Etna with a good beer or a good red wine produced on Etna - and our home village sits on a little old cone and thus is more protected than many other areas.

For the moment there is no visible activity at Etna except for vigorous gas emission, sometimes rhythmic, and numerous small explosion quakes. Things might still take weeks to months to evolve to some more serious summit activity.

@Boris Behncke, Catania, Italy, You have a email from me. I hope it arrives.

In regards to Etna, I think that there is more going on the meets the eye and I am expecting some explosions in two to four weeks time. But my data is limited and I might be wrong because of that.

@Carl the slightly Ahab

Back during an interdiction ops, we ran across a beat to h3ll and back, storm rigged sailboat. The occupant asked for a whiskey, so we gave him the position. He then clarified that he knew the position and actually wanted whiskey if we had any to spare.

Odd things you find at sea.

>I am expecting some explosions in two to four weeks time.

*snort* After Boris patiently explaining that INGV is fully expecting a *continuation* of sporadic deep phreatic explosion with occasional ash emissions, with good potential for increasing activity, I would say your 'call' is a safe bet.

@Peter Tibben #47
Great set of Etna pics, and informative descriptions! Thanks for link.

At 15.08 on wednesday 25 I was arriving to the summit of the Etna central crater. I listened a profound but not loud sound and immediately appeared a brown and white cloud of ash like a mushrom. I didn't see nothing more because I ran down the slope as quick as I could. Three minutes later I turned for the first time and I was very impressed by the enormous dark mushrum that was over me. Luckely the wind was flowing in the opposite direction and I saw a gentil man that was waiting for me at the base and the bus of the funivia that was collecting people. I'm very impressed. The next day I put a candle to Santa Agata for my great luck.

#66 @Maria Congost
Surely you were lucky. That's the reason why I say I prefer watching these wonders of nature from afar. But I must confess I kind of envy your experience. You will have a story to remember for the rest of your life. Boris: keep two eyes open, you and your family.

Etna webcam timelapse 28 August 2010
http://www.youtube.com/watch?v=mRYOIkeISxA

@Passerby #64

Interested in safe bets?
http://i34.tinypic.com/1y0oc3.jpg

** double snort **

*cocking an eyebrow*. Etna at 28 to 1, but Vesuvius at 12 to 1?

Geologically-challenged dolts.

#68 @d9tRotterdam: Good to have you back with your timelapses. We can see quick bursts of ash venting from the main crater.
#69 Yellowstone 50/1 (????). I'd place my bet at Galeras. Recent activity didn't correspond to all the buzz that took place before. And then, Katla? Who knows?

Oh look! The odds have changed ... :-P

http://i54.tinypic.com/4rdi5h.jpg

Umm... Santa Maria/Santiaguito at 33-1 might be worth a punt.

I am new here at the college, I'm just stopping by to see everything. Do you have any recommendations for clubs to join?

Thanks! :)

I definitely like your blog but i highly recommend you look at the punctuation on a number of of your articles. Many of them are packed with spelling errors and I believe it is very frustrating to say the least nonetheless I probably will come back again.

Due to numerous region, territory or country cultural specific reasons, a game that looks perfectly fine in one country may be looked upon as the devil incarnate in another. This is one of the reasons why video game localization - as opposed to translation- is a must for video games.

That said, these facts raise an important questions: when does the "localization" of content stop being "localization" and turn into full-on "censorship"? And is that something one should accept?

As a recent example, Yakuza 3 on PS3 shows well how thin the frontier between censorship and localization can be. A lot of gamers complained because some scenes and important elements of the games where changed when the game made it to US.

Now the question is: do all of these elements actually required to be changed? Isn't that just based on a stereotype that American gamers tend to be more religious and concerned about nudity and violence? Gamers were most likely expecting something different after reading about the game in specialized media

Now if you look at it, most gamers actually are adult and will absolutely not care to find certain elements. In fact, their absence may come as a huge disappointment for them and alter their gaming experience. So should developers think a little more about what public they are targetting, or just assume anyone may buy the game by accident, and thus edit it?.

Video game localization is an important process to bring games to new people, and shouldn't be taken that lightly.

What do I miss about my wife? Her absence.

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I salute you, I really like the way u put the thing... maybe you could join my internet page and tell a few corrections. Thanks in advance :)

Good story! I am going to need a bit of time to entertain your article!!

Galeras Erupts

eklemetti — Wed, 25 Aug 2010 06:17:18 +0000

Galeras Erupts

An undated photo of the crater at Galeras.

I am literally out the door, so I will fill this article a little more after my prior academic obligations, but there are reports of an eruption at Galeras in Colombia overnight. 8,000 people living near the volcano have been evacuated as INGEOMINAS moved the alert status at the volcano to "Red". Not much out there on the details of the eruption beyond this intriguing statement:

Diego Gomez from the Pasto Observatory of Vulcanology and Seismology said that due to the atypical, non-explosive eruption, another eruption is imminent.

Galeras the most active volcano in Colombia (at least in the last 50 years), last erupting in January of this year.

eklemetti Wed, 08/25/2010 - 02:17

Tags

Posted by: Henrik, Swe | August 25, 2010 3:40 AM
8
Hello
After the strong earthquakes in recent days, the Galeras volcano erupted this morning in Columbia.
http://intranet.ingeominas.gov.co/pasto/P%C3%A1gina_Principal
Posted by: Sherine, France | August 25, 2010 7:13 AM
9
Thanks, @Sherine:
I got this from El tiempo, Colombia:
"The eruptive event occurred in the early hours of Wednesday, after which the alert level was raised from orange to red indicating that another eruption could be recorded in minutes, therefore she reiterated the call for residents to attend to shelters. According to Dr. Martha Calvache, deputy director of Ingeominas, the incident happened around 4:00 am and the organization and the state is monitoring the volcano.
The signal of the Galeras has lasted for nearly an hour, one of the largest that have occurred in the area, as added Calvache."
www.eltiempo.com
Posted by: Renato Rio | August 25, 2010 7:32 AM
10
They say that although weather conditions at the site are good, yet they don't know the kind of material extruded from the volcano.
www.elespectador.com
Posted by: Renato Rio | August 25, 2010 7:41 AM
11
#8 Link for the Galeras web cam:
http://intranet.ingeominas.gov.co/pasto/Imagen_en_l%C3%ADnea
Posted by: Renato Rio | August 25, 2010 7:49 AM
12

Thanks, @Renato for the link
I found another interesting link
http://www.vulkaner.no/v/volcan/galeras-e.html
http://www.vulkaner.no/v/volcan/galeras-e.html
Posted by: Sherine, France | August 25, 2010 8:21 AM
13
I get the feeling that Galeras could turn nasty since the residents flat out refuse to go to shelters with the words "nothing will ever happen"...
Posted by: Carl | August 25, 2010 8:46 AM

The info from onaired.com -- director of Red Cross relief Colombian, Carlos Ivan Marquez, said that a red alert status was ordered. People from villages nearby should evacuate to shelters, but since this kind of eruption is common, few have left their homes. GOES records a single eruption.

An "atypical" and "non-explosive" eruption???

Mind you, since the story also claims that the last Galeras eruption sent "streams of lava" down the slopes, I think the reporting leaves something to be desired

Finally found a better Etna webcam. She's steaming away. INGV thermo cam is neutral. Must be normal. Seismometer, south flank, shows a clear spike, few minutes ago.

http://www.guide-etna.com/webcam/schiena000M.jpg

OT, but here are some wonderful paintings/ lithographs of Vesuvius from the 18th centruty

http://bibliodyssey.blogspot.com/2010/08/campi-phlegraei.html

Just browsing for the relevant pages on Galeras - if anyone else wants the links:

http://www.ingeominas.gov.co/
& if you click the pdf with google translate, you get the description of how they reached the decisions at 4am. Sounds a bit like doing a jigsaw in the dark - making some guesses as everything under cloud cover! They do describe local ash deposits though.

We've had a powerful explosion at Etna's summit early this afternoon, which produced an ash plume about 1 km tall and weaker ash emission for about 20 minutes. The source of the explosion was a vent in the western part of the Bocca Nuova, one of the four summit craters of Etna.

I have posted a preliminary report at the INGV-Catania web site, both in Italian and in English, and you will appreciate the photos ...

For more competent info on Galeras (in Spanish), try this:

intranet.ingeominas.gov.co/pasto/P%C3%A1gina_Principal

And looks like a lovely day there on the webcam:
http://intranet.ingeominas.gov.co/webcam/pasto/volcan-galeras000.jpg

Ha! I just happened to catch the opening salvo of an ash emission at Etna.

http://www.hotelcorsaro.it/

Meanwhile, French engineers are preparing to drain a lake that has formed under the Mont Blanc glacier. The last time a subglacial lake flooded the valley below was 1892.

France to drain lake under Mont Blanc glacier
www.bbc.co.uk/news/world-europe-11080827
www.spiegel.de/international/europe/0,1518,713669,00.html

Reducing the Pressure (excerpt, Der Spiegal)

>Engineers are planning on pumping one-third of the water from a pocket dozens of meters below the glacier's surface. "Pumping off the water will reduce the pressure in the pocket and allow it to drain off in a more controlled fashion," said Jean-Marc Peillex, the mayor of Saint-Gervais-les-Bains, in a statement.

http://en.wikipedia.org/wiki/Mont_Blanc (with location map)

Webcam 3, back to updating properly.
http://www.guide-etna.com/webcam/wcsrc/wc3.htm

Etna is awake.

Oh, finally found the page - on the home page intranet.ingeominas.gov.co/pasto/P%C3%A1gina_Principal

click on the videos link on the right you can see the thermal cams from last night of the Galeras activity.

Man, Ingeominas nailed the situation perfectly, on August 24th, 6pm (last report before eruption the following morning 4am):

' With fluctuations in the energy levels of the signals, the record remains significant seismicity related to both fluid dynamics as fracturing of crustal material in the area of the volcano. Last night at 11:02 pm highlights another Volcano-Tectonic earthquake located about 800 m south-east of Galeras, about 2 km deep, which had a local magnitude of 3.4 on the scale of Richter and was reported as felt by some residents of the city of San Juan de Pasto.

In aerial reconnaissance of the surface activity, the emission was observed pulsating white gas in small quantities. Measurement of Sulfur Dioxide instrumental in both the permanent stations west of Galeras as mobile equipment on the Beltway, continue to show values of the gas flow at low levels.

In general, seismic activity has occurred since Aug. 20, is the largest energy values compared with either of the processes has been Galeras since 2004, especially the contribution of seismic processes associated with crustal material fracturing in the area of the volcano. We consider that there are characteristics of a partially sealed, facilitating conditions of pressure and instability, which can evolve into states explosive eruptions. '

@ EIRIK, emskib, Boris, Passerby - thanks for the links, bookmark bar loaded and ready....

Yes Passerby, we could be in a pattern of pressure cooker

Sherine, merci! Incidentally, you beat both Erik and Sally Kuhn Sennert to it, well done!

I don't know if you remember it, but I recall that back in late March or early April, Dr Behncke told us about a new cycle beginning at Etna, but also said that an eruption could be several months away and hoped that she would would wait until after the summer holidays.

We now have August 25th, holiday season all but over and Etna rumbling...

@Boris Behncke, Catania, Italy, I don't know how accurate I was this time. But back in April I did comment on this being a chance. But with volcano like Etna, they are always in risk of sudden eruptions so my opinion might not mean a lot, or anything at all.

I don't know if you got any warning or not. But this looks like a good size explosion in Etna.

I do lack a lot of data on Etna at the moment. So that leaves me part on the dark on what is going on inside the mountin.

Older thread from April.

eruptions/2010/04/etna_showing_signs_of_new_erup.php

@Erik, yesterday "volcano day"? - I think you missed it for 24 h! :)
@Boris, thanks for the link. After all our Etna talking we were granted an eruption to lurk at.
@JÃ³n FrÃmann: All we needed now to complete this our Volcano Day was Eyjaf's return or some Katla news. Actually, there was a significant steam plume at Eyjaf this morning.
#13 @Sherine: Couldn't paste our earlier talk from this morning. But thanks for your readiness in alerting us on Galeras.

Err... "wow"

Found the USR quake catalog... did a plot of a little over a years worth of quakes.

You can actually visualize the subducting plate dropping down under Columbia. There are about 3 areas where it is scraping, making the deeper quakes. The large blob is two of them viewed across the plane of the slab in that area. This view angle was selected to emphasize the bend in the slab.

http://i33.tinypic.com/21deseg.png

More on Etna and Galeras: http://scienceblogs.com/eruptions/2010/08/a_busy_day_for_etna_and_galer…

@14thank you, it'sa pleasure to participate in this blog and be with you. I have no merit, I've been watching the area since the earthquake of August 14. Thank Renato I put here the link from this morning
http://www.vulkaner.no/v/volcan/galeras-e.html
A follow volcano Cerro Machin also
Sherine "Windchill de la Terre du Futur"

@18 What a graphic! Can you spin it so we can look down the length of the zone? I want to see if there is a directional transition at the critical length, delta, at 200 Km depth.

@17 Renato Rio, You had to bring up Volcano Day and Katla, hehe, take at look at this link,

http://www.ruv.is/katla/

Double click it to enlarge and let me know if you notice a darker cloud underneath the regular ones, there is also a light grey film on the left hand side of the camera, plus I've never seen the camera shake like that before.

@R. Hurst
As you see, I'm still pretty much attached to these Icelandic volcanoes. ;)
As for the clouds and the shaking, I've learned over time that they are quite frequent due to winds and weather features of these glaciers near the ocean.
But some day Katla will erupt, and it could be our next "volcano day".
For now, we will be kept very busy by Etna and Galeras.

@Passerby

A bit difficult. It's curved.

Here are a few different views so you can tell me where you want the view oriented from.

View East

i33.tinypic.com/2wlub1h.png

View North East

i36.tinypic.com/8winmx.png

View North by North East

i38.tinypic.com/2gugwo1.png

View North

i38.tinypic.com/5l13fc.png

Thanks; the view looking eastward answered my questions.

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Tuesday Tidbits: EyjafjallajÃ¶kull, Yasur, mud on Mars and more

eklemetti — Tue, 24 Aug 2010 02:12:24 +0000

Tuesday Tidbits: EyjafjallajÃ¶kull, Yasur, mud on Mars and more

Finally, a chance to catch up a bit ... !

Yasur erupting in May of 2010.

Some news from the world of volcanoes:

The BBC has a series of videos one the fallout from the EyjafjallajÃ¶kull eruption - including a look at the area around the volcano and how the economy has been affected by the eruption. However, things seem pretty quiet at the summit of the EyjafjallajÃ¶kull summit where snow can begun to settle without melting - and the Icelandic Met Office appears to think that the eruption is more or less (but not officially) over. And take this press release as you will, but a recent study by a UK moving company (UniBaggage.com) claims that parents moving their children off to university each fall release twice as much CO₂ than the EyjafjallajÃ¶kull eruption.
Most people think of volcanoes being bad for the economy, but in places like Vanuatu, volcanoes are vital to the local economy, thanks to a consistently active volcano. Yasur on Tanna Island is visited by tourists regularly - along with providing a source for fertile soil. The description of the visits are a bit, well, harrowing, but those are the risks if you're going to visit an erupting volcano.
There were some great new shots from space from the NASA Earth Observatory of two active volcanoes. The first is an image of the intensified activity at Sakurajima in Japan - complete with an impressive ash plume and ~~a pyroclastic flow heading to the south~~ steam-and-ash plume from a lower vent on the south flank. The second is an image of the new dome complex on Chaiten in Chile - and it looks pretty calm compared to when it started back in 2008 (when this blog got its start too). However, this is still a lot of the area covered with what looks like fresh ash, so the domes continue to intermittently coat the area with ash.
There was also an article on MSNBC that wasn't about magmatic volcanoes, but rather mud volcanoes ... on Mars no less. The region on the northern hemisphere called Acidalia Planitia appears to have a high concentration of features that look like terrestrial mud volcanoes. The article in Icarus suggests that there are potentially 40,000 mud volcanoes in the area that likely formed in early Amazonian times on Mars (over 1 billion years ago).

eklemetti Mon, 08/23/2010 - 22:12

The pic of Sakurajima may be mislabeled. The ash plume looks like it is emerging from the main crater while the so-called "pyroclastic flow" looks to me like steam emerging from the smaller Showa crater. That is my impression anyway.

It's interesting the fact that ChaitÃ©n is covered by snow, indicating a cooling of the dome. In the OVDAS site, Caldera camera (frozen for a long time), you can see the base of the dome with snow.

@Guillermo
Before the eruption, did ChaitÃ©n show a perennial icecap, or it just forms in winter (when not erupting)? Could melting mean an eruption at sight?

MÃla's cams showing a significant steam plume for the first time in days. Could that be related to recent EQ activity?
Wednesday
25.08.201003:32:2163.694-19.5581.1 km2.190.014.2 km WNW of BÃ¡sar
Wednesday
25.08.201003:32:2063.639-19.3661.1 km1.690.025.7 km W of GoÃ°abunga

just checked the ÃÃ³rÃ³lfsfelli cams. FLIR is back in action, and yes there is a steam plume again.

@Alastair:
FLIR is back, I forgot to mention. Have you tried the cam from Ãorvaldseyri? Contrast is now too sharp, but earlier you could neatly see the rising plume. Maybe the crater lake is boiling now.

All this recurring steaming would suggest (to me anyway) that water is not just sitting in the crater bowl but penetrates deeper and deeper into the mountain. Her next eruption could prove to be, erm..., "interesting".

Hello

After the strong earthquakes in recent days, the Galeras volcano erupted this morning in Columbia.

http://intranet.ingeominas.gov.co/pasto/P%C3%A1gina_Principal

Thanks, @Sherine:
I got this from El tiempo, Colombia:
"The eruptive event occurred in the early hours of Wednesday, after which the alert level was raised from orange to red indicating that another eruption could be recorded in minutes, therefore she reiterated the call for residents to attend to shelters. According to Dr. Martha Calvache, deputy director of Ingeominas, the incident happened around 4:00 am and the organization and the state is monitoring the volcano.
The signal of the Galeras has lasted for nearly an hour, one of the largest that have occurred in the area, as added Calvache."
www.eltiempo.com

They say that although weather conditions at the site are good, yet they don't know the kind of material extruded from the volcano.
www.elespectador.com

#8 Link for the Galeras web cam:
http://intranet.ingeominas.gov.co/pasto/Imagen_en_l%C3%ADnea

Thanks, @Renato for the link

I found another interesting link

http://www.vulkaner.no/v/volcan/galeras-e.html

I get the feeling that Galeras could turn nasty since the residents flat out refuse to go to shelters with the words "nothing will ever happen"...

Erik just opened a thread for Galeras. I'll paste your comments over there.

Light from the moon makes the steam plume visible during the night tonight.

April 18 photos of Eyja. I found while looking for photos of glacier Ok. The photographer just happened to be on the spot, shooting clothing company ads. Is the second photo (looking down into the snow-coated cone) a photo of Eyja.?
http://www.partytow.com/e/?p=7922

Hello
Last news from Galeras, but I do not see this report on the site Ingeominas :
August 26th, 2010
This morning the alert-level was reduced to ORANGE.
Seismic activity went on for about 12 hours after the eruptive at 4 AM local time, but intensity
was redused during the day. However, another seismic event happended again late afternoon, similar
to the one at 4 AM. Ashfall is reported within 30 km from the crater, and there are possiblilities
that a new crater has opened up. Up to 3.000 tonns sulfur dioxide up to 400m above the top was partly
visible duringthe day. Of the 8.000 inhabitants to be evacuated, most of them refuse to live their homes
so far. Magma is still floating near the opening, and therefore reason to be prepared for new intensity.
Source : http://www.vulkaner.no/v/volcan/galeras-e.html

I read this at RÃV News, but not quite sure of what it means:
"New cracks were found in some of Sprengisandur up, but they are believed to have formed in the spring. PÃ¡ll Einarsson, mineral physicists believe cracked delayed by attacks by the eruption under VatnajÃ¶kull GjÃ¡lp in 1996. " (Google translated)
http://www.ruv.is/frettaskyringar/innlendar-frettir/nyjar-sprungur-a-sp…

Two of the Mila cams are down now, so I went exploring and found that Weather Underground has a satellite view that might be useful, if Eyja. becomes active again. I had to zoom and drag the map to find the glacier with Eyja.
http://www.wunderground.com/wundermap/?lat=64.12999725&lon=-21.89999962…

Below the map is a slider that will give you animation if moved to the right, for more frames. Unfortunately, I didn't think of using this site during the eruption, and I'm not sure how useful it would be. I do use the radar images when a storm is predicted for my location, to see how fast it's approaching. The image refreshes perhaps twice an hour.

Looking at Wunderground for Catania Italy, I can see many small craters after zooming and dragging to Mt. Etna. Some craters have black around them (ash?).
http://www.wunderground.com/wundermap/?lat=37.47000122&lon=15.05000019&…

Erik: Just saw the Nasa image of Chaiten, too bad the Chilean webcam has been inoperative since 6/20. I started reading about volcanoes when your blog started (and Chaiten erupted). Congrats on the great work.

I love your site lol

Etna Week (Part 2) - The current dynamics and activity of Etna

eklemetti — Wed, 18 Aug 2010 04:14:53 +0000

Etna Week (Part 2) - The current dynamics and activity of Etna

This is Part 2 of 3 from guest blogger Dr. Boris Behncke. Check out Part 1 here.

The current dynamics and activity of Etna
by guest blogger Dr. Boris Behncke

The recent behavior of Etna is characterized by nearly continuous eruptive activity from the summit craters and eruptions from new vents on the flanks at intervals of a few years to decades. Summit eruptions vary from quiet lava emission to mild Strombolian explosions to high-discharge-rate Hawaiian to sub-Plinian style lava and fire fountaining accompanied by the emplacement of fast-moving lava flows; usually the strongest activity concentrates in episodes lasting from a few tens of minutes to a few hours. Most flank eruptions are predominantly effusive - that is, characterized by the emission of lava flows, and explosive activity during these events is often limited to Strombolian explosions or mild spattering. This leads to the emplacement of extensive lava flow-fields and only minor cones are built at the eruptive vents, including the smallest constructive volcanic features, called hornitos (Spanish: "small furnaces").

Pyroclastic constructs on Etna come in all forms and sizes. The photograph at top shows a cluster of steep, narrow spires a few meters tall built up around small vents by the ejection of liquid blobs of lava (spattering activity), seen against the backdrop of the huge composite cone of the Southeast Crater, one of the summit craters of Etna. The conspicuous yellow hue is from sulfur deposits. The bottom photograph shows the largest pyroclastic flank cone formed during the historical period, Monti Rossi at about 700 m elevation near the village of Nicolosi, on the south flank of Etna. The name, literally, means "the red mountains" - the plural stands for the two summit peaks, the crater actually lying between them; but the original name - Monte della Ruina, "mountain of devastation" - more accurately refers to the catastrophic impact of this eruption. The cone is approximately 250 m tall from base to top. Photos taken in 1999 and 2000 by Boris Behncke

Some flank eruptions, however, show much more intense explosive activity, like the 2001 and 2002-2003 eruptions, and a number of previous eruptions as in 1852-1853, 1879, 1886, and 1892. Conspicuous pyroclastic cones (also called cinder cones or scoria cones) are formed during such explosive activity, which can be up to a few hundred meters tall, like the prominent double-peaked Monti Rossi cone formed during the unusually voluminous and explosive 1669 eruption on the south flank of Etna. A typical feature of the flank vents is that each erupts only once, like the eruptive centers in monogenetic cone fields worldwide (e.g., the famous "new volcano" ParÃcutin in Mexico, 1943-1952). As a matter of fact, the numerous pyroclastic cones of Etna could be considered a monogenetic cone field, were it not for the huge central volcano on whose flanks they are sitting.

Flank eruptions represent a considerable hazard for the populated areas on the lower flanks of the mountain, which are home to approximately one million people. During the historical period, new flank vents have occasionally opened within those areas that are now densely urbanized, especially on the southern and southeastern flanks, most recently in 1669 near the village of Nicolosi. During the past 1000 years, lava flows have reached the coast of the Ionian sea on three occasions, in ~1030, 1224, and 1669. The map below shows the extent of historical lava flows, distinguishing those of flank eruptions (in different shades of pink, yellow and red) from those emitted during summit eruptions (in green). It is evident that summit lava flows have never come anywhere close to the populated areas and therefore summit activity poses no immediate threat to those areas.

Map of historical lava flows of Etna, distinguishing summit from flank eruptions. Modified from Crisci et al. (2010)

Evolution of the summit area
The summit area of Etna has undergone profound changes in the past century. Until 1911, there was a single large crater at the summit, about half a kilometer wide, and truncating a broad cone about 300 m tall, which had grown since a major summit collapse accompanying the large 1669 flank eruption. This crater was known as the Central Crater. At the beginning of the 20th century, it was a funnel-shaped pit about 200 m deep, but intermittent eruptive activity on its floor led to its gradual filling, and in the mid-1950s, lava flows for the first time overflowed from the Central Crater onto the upper flanks of the volcano. Vigorous activity from several vents within the crater in the early 1960s led to the complete filling and obliteration of the Central Crater, and two large cones built up around the two main vents, the Voragine ("Big Mouth") that had been present since 1945, and a smaller vent known as "the 1964 crater". In 1968, a third vent opened, which became known as Bocca Nuova ("New Mouth"), and which progressively enlarged in diameter mostly due to the caving in of its unstable rims.

For much of the 1970s to 1990s, the evolution of the Voragine and the Bocca Nuova was characterized by periodic intracrater activity and rim collapse, leading to their growth in diameter, until the two pits began to coalesce with only a thin septum remaining between the two, known as the "diaframma" (diaphragm). During a period of exceptionally intense summit eruptions in 1997-1999, both craters were filled to overflowing before subsidence of magma in their conduits led to the formation of new collapse pits, which gradually enlarged and coalesced into a single large depression, Etna's new Central Crater.

Aerial views of Etna's summit area showing the evolution from the single Central Crater in the early 20th century to the currently four summit craters. Top photograph was taken in the 1920s, when the Northeast Crater was already present (but is barely discernible in this view); the size and depth of the Central Crater is well recognizable here. The view is from the west. Center photo is of 1961 and shows the Central Crater filled-to-overflow with pyroclastic cones and lava; the much smaller Northeast Crater is seen behind the Central Crater to the left. The view is from the south. Photograph at bottom was taken in May 2008, the Bocca Nuova and Voragine are in the upper center, nearly coalescing into a new Central Crater, whereas the Northeast Crater is emitting a dense white vapor plume at right, and the Southeast Crater is at center left, showing conspicuous light-colored sulfur deposits lining its rim. The view is from the east. Photographers for top and center photographs unknown, bottom photo by Stefano Branca (INGV-Catania)

In the spring of 1911, a collapse pit opened at the northeastern base of the central summit cone, from which issued a vapor plume but which showed no eruptive activity until 1917. This pit became known as "the Northeast subterminal Crater" (the term subterminal is applied to eruptive vents lying close to Etna's summit craters and showing a eruptive behavior different from the vents of flank eruptions); it is now called Northeast Crater. The new crater remained a pit until 1923, when a small cone grew within and filled the pit, leading to the first lava overflows from the Northeast Crater. In the 1950s, cone growth intensified, as the crater became the site of virtually continuous, mild Strombolian activity accompanied by slow lava emission; this type of activity was termed "persistent" and for a long time was believed to represent the most common type of Etnean eruptive manifestation. In 1977, however, the Northeast Crater switched to a more dramatic form of volcanism, which proved highly efficient in making it become the highest point on Etna - brief but violent episodes of high lava fountaining with voluminous, fast-moving lava flows and tall tephra columns.

The Northeast Crater showing different types of eruptive activity. Top photo, taken in 1969, shows the cone of the Northeast Crater nearly as tall as the rim of the former Central Crater (in the foreground), and displaying weak Strombolian activity from its summit, while lava quietly issues from a small crack on the left side of the cone. This activity lasted with few interruptions from 1955 until 1971, and again from 1974 until 1977. Photographer T. Micek (?). The bottom photograph shows one of about twenty episodes of violent fire fountaining and tall tephra plumes that occurred between July 1977 and March 1978; this was one of the latest episodes of that series. View is from the village of Monterosso on the southeast flank of Etna, photo by Carmelo Sturiale.

By 1978, the Northeast Crater had grown to about 3340 m elevation and thus become the highest point ever measured on Etna. It produced a few more episodes of lava fountaining in late-1980 and early-1981, which brought its height to 3350 m. On 24 September 1986, an unprecedentedly violent eruptive episode caused a reduction in height by 10 m of its cone, and further collapse occurred throughout the following decade. Although the Northeast Crater went through another phase of intense activity in 1995-1996, its height continued to decrease, and in 2007 was 3329.6 m (Neri et al., 2008).

The Southeast Crater seen from the air immediately after its formation in spring 1971 (top) and in May 2008 (bottom). Note that the field of view in the latter photo is much wider than in the earlier. Photos taken by Carmelo Sturiale and Boris Behncke

The latest addition to Etna's summit crater family is the Southeast Crater, which formed during a flank eruption in May 1971 at the southeastern base of the central summit cone as a sort of pressure valve - while lava was emitted a few kilometers further downslope to the northeast, it emitted vapor-rich ash clouds for a couple of weeks. It then remained quiet until spring 1978 and then sprang to life with high lava fountains accompanying a series of flank eruptions in rapid succession - April-June, August, and November 1978, and August 1979. Since then, it has been the most persistently active vent on Etna, and its appearance on the stage was accompanied by a marked change in the eruptive behavior of the volcano. As a matter of fact, since the birth of the Southeast Crater, Etna has practically doubled its average output rate (Behncke and Neri, 2003a).

The Southeast Crater has grown much more rapidly than the Northeast Crater, and nearly 40 years after its birth its cone stands approximately 300 m above the site where it came to life in 1971, reaching a height of 3290 m as of 2007. This rapid growth is the result of numerous periods of frantic eruptive activity which are unparalleled in the documented history not only of Etna but of all volcanoes on Earth. The culmination was a series of 64 episodes of violent lava or fire fountaining between January and June 2000, followed by two more in August and 16 more in May-July 2001 (Behncke et al., 2006). The Southeast Crater has erupted more recently in 2006 and 2007-2008, again producing numerous episodes of strong Strombolian activity and lava fountaining, the latest - and possibly most violent - on 10 May 2008, when lava flows advanced 6.4 km in 4 hours, an unprecedented value for Etnean summit eruptions.

What are the reasons for such variable and, for a basaltic volcano, often unusually violent explosive behavior?

Eruption types and styles
It seems that much of the explosivity of Etna is driven by magmatic gases, foremost water vapor (H₂O) and carbon dioxide (CO₂). Etna is emitting significant quantities of these gas species, up to 200,000 metric tons of water vapor and about 20,000 tons of carbon dioxide per day. Eruptions tend to be more explosive when magma rises fast, which is the case when batches of new primitive magma enter into the plumbing system of the volcano, so that the most explosive eruptions of Etna in the past few thousand years have also produced the most mafic magmas (Coltelli et al., 2005; Kamenetsky et al., 2007). In particular, a powerful sub-Plinian eruption about 3930 years before present produced picritic magma, which was also extremely enriched in CO₂. In contrast, the Plinian eruption of 122 BC was apparently triggered by the sudden decompression of the magmatic system, which led to the catastrophic exsolution of gas although the pre-eruptive water content of the magma was found to be only about 1 weight-% (Del Carlo and Pompilio, 2004).

Hypothetical and simplified scheme of the magmatic plumbing system of Etna, illustrating magma transport feeding summit activity and the two different types (lateral vs. eccentric) flank eruptions, from Behncke and Neri (2003b)

Most magma ascends to the surface through the central conduit system of Etna, which leads to the frequent summit activity. Unless magma ascent is very rapid, much gas is lost from the magma during its ascent to the surface, and significant volumes of relatively gas-poor magma are stored in the shallow plumbing system of the volcano. During many flank eruptions of Etna, such gas-poor magma exits laterally from the central conduits, resulting in relatively weak or almost no explosive activity but copious lava outflow. Most flank eruptions during the 20th century were of this type; they are commonly called "lateral" flank eruptions. Typically such eruptions are accompanied by the cessation of summit activity and some collapse at the summit craters, as the central conduit system is drained of magma.

Extremes in eruptive styles at Etna: totally non-explosive extrusion of gas-poor lava near the Southeast Crater in 1999 (top), and the 10-km-high eruption column formed during a sub-Plinian eruption from the Voragine on 22 July 1998 as seen from Catania. Photos taken by Boris Behncke and Sandro Privitera

Another type of Etnean flank eruption is characterized by much more pronounced explosive activity, resulting in the emission of significant volumes of ash even for prolonged periods of up to several months, as in 1892, 2001, and 2002-2003. These eruptions occur when magma, rather than rising through the central conduits, pushes its way forcefully through the flank of the volcano to form new conduits called "eccentric" or "peripheral" (Rittmann, 1964; Neri et al., 2005). Being in a closed system until eruption, the magma does not lose significant amounts of its gas during ascent, and therefore the ensuing activity is considerably more explosive. The 1974 and 2002-2003 eccentric eruptions did in fact produce more tephra than lava (Andronico et al., 2004; Corsaro et al., 2009), belying the widespread notion of Etna being a rather non-explosive volcano!

Eruptions and flank instability
The question why Etna makes flank eruptions at all is not easy to answer. Certainly the fact that the volcano lies above the intersection of several main regional fault systems helps in rendering its flanks unstable and subject to fracturing. Mazzarini and Armienti (2001) demonstrated that the distribution of Etna's flank cones is largely controlled by intersections between tectonic lines of weakness. It has also been suggested (e.g., Chester et al., 1985) that the hydrostatic (or rather "magmastatic") pressure exerted on the conduit walls by the rising magma column within the conduit might lead to the opening of lateral cracks through which the magma could escape to feed flank eruptions. Bousquet and Lanzafame (2001) specified that magma transfer from the central conduits into the flank occurred in a more or less horizontal manner, rather than rising upward vertically. All of these scenarios concerned exclusively lateral flank eruptions, not eccentric ones, which had effectively been nearly forgotten prior to the 2001 and 2002-2003 eruptions.

The Pernicana fault cuts through the northeastern flank of Etna, from an elevation of about 2000 m at the Northeast Rift, down to sea level near the village of Fondachello. From Neri et al. (2004)

Displacement along the Pernicana fault during the massive flank movement of 2002, along the Fornazzo-Linguaglossa road (top) and the Catania-Messina highway (bottom). From Neri et al. (2004)

Since the early 1990s scientists (Borgia et al, 1992; Lo Giudice and RasÃ , 1992; Rust and Neri, 1996; Bousquet and Lanzafame, 2001) proposed that a large portion of the volcano, encompassing its eastern and southern flank sectors, was subject to lateral sliding, much in the same manner as the southern flank of KÄ«lauea on Hawai'i. There was some debate as for the cause of the sliding - was it caused by gravitational pull, the push of accumulating magma below the volcano, or by more shallow intrusion of magma into the flanks? Also the extent of the mobile sector was not unanimously defined; whereas there was agreement that the northern boundary of this sector was defined by the transcurrent (mostly horizontally moving) Pernicana fault, the southern or southwestern boundary was variously attributed to different fault systems cutting the southeastern and southwestern flanks of Etna. It is now known that the extreme southwestern boundary is the Ragalna fault system (Rust and Neri, 1996; Rust et al., 2005; Neri et al., 2007).

Speculation became truth in the fall of 2002, when a large sector of the eastern and southeastern flank of Etna underwent a massive move toward the Ionian Sea. During a powerful and complex flank eruption in the summer of 2001, the southern flank and summit area of the volcano were violently ripped open, and the eastern flank started to move away from the remainder of the mountain at accelerating speed. Though this was recognized only in hindsight (Bonforte et al., 2008, 2009; Puglisi et al., 2008), many of us were convinced that the 2001 eruption had significantly destabilized the volcanic edifice, and that further flank eruptions would occur from now on in rapid succession.

On 24 September 2002, a shallow earthquake occurred on the northeast flank of Etna, along the upper portion of the Pernicana fault system, which had been very active during the 1980s but had not shown any seismic activity or significant displacement since 1988. The earthquake was accompanied by conspicuous ground rupturing along the fault, similar to numerous events between 1980 and 1988. A few weeks later, on 27 October 2002, a more pronounced movement along the fault heralded the onset of a new flank eruption, which affected both the south and northeast sides of Etna and destroyed numerous tourist facilities as well as forested areas. During a few days, a part of the northeastern flank moved by more than 2 m eastward; then the movement extended over an ever larger area to the southeast side of Etna, where earthquakes accompanying the displacement caused severe damage in several villages, such as Santa Venerina and Milo.

Top: The sector of Etna's eastern to southern flanks affected by flank instability and displacement is shown in pink. PFS = Pernicana fault system; VB = Valle del Bove; RN = Ripe della Naca; ZE = Zafferana Etnea; SV = Santa Venerina; TFS = Timpe fault system; AC = Acireale; TF = Trecastagni fault; R = Ragalna fault system. From Neri et al. (2004). Bottom: Distribution of earthquake epicenters accompanying the 2002 eruption and flank movement helped to distinguish several blocks (Blocks 1, 2 and 3) within the unstable sector, moving at different times and speeds. From Neri et al. (2005)

This immense mass movement, which was later revealed to have involved about 2000 cubic kilometers of rock (Walter et al., 2005), both of the volcanic pile and of the underlying sedimentary basement, was documented in extreme detail, thanks to improved monitoring equipment placed on the volcano a few years before. It could thus be established that the movement started at the Pernicana fault in the northwestern portion of the moving sector, and then extended both eastward - to the Ionian coast - and southward, affecting numerous fault systems cutting through the eastern and southeastern portions of the volcano. In the entire area, earthquakes were strongly felt and often caused damage, and cracks ripped through buildings and other constructions as well as roads.

Since the fall of 2002, the movement of Etna's eastern flank has continued, most of the time at somewhat reduced speed, but often with new accelerations accompanied by shallow earthquakes. Since 2004, the southern block in the unstable sector has started moving slowly southward. At the Pernicana fault, dramatic slip accompanied by earthquakes and rupturing of the ground surface has occurred several times in 2003 and 2004, and again in early April 2010. This all indicates that the volcano has not yet returned to a state of relative stability and equilibrium as before 2002 (or 2001, if we consider the eruption of that year a significant factor in destabilizing the volcano). As a matter of fact, the behavior of Etna has changed profoundly since 2001.

Fluctuations in Etna's eruptive behavior since 1600 AD, with marked variations in the frequency, style, and size (volume) of eruptions. The output rate was exceptionally high from about 1607 until 1669, when ten - most of them very large - flank eruptions occurred (see black vertical bars in the graph at the bottom of the figure) and up to 3 cubic kilometers of magma was erupted. Very low output and few flank eruptions are seen during the following ~100 years, until the 1760s when flank eruptions pick up in frequency and size. A marked acceleration in the activity of Etna is evident starting in the second half of the 20th century. Unpublished figure by Boris Behncke and Marco Neri

Eruptive cycles
If one looks at the historical record of Etna's eruptions, it becomes evident that the intervals between these events, as well as their characteristics (duration, location, volume, eruptive style) vary strongly. Unfortunately the record is complete only since the beginning of the 17th century, yet these past little more than 400 years show remarkable fluctuations in Etna's activity. The first 70 years of the 17th century showed unusually high levels of activity, with frequent summit activity and ten flank eruptions. Some of these flank eruptions lasted for years - the one of 1614-1624 being the longest flank eruption in the historical record of Etna - and produced large volumes of lava (1614-1624: about 1 km3, 1634-1638: about 200 million m3, 1646-1647: about 160 million m3, 1651-1653: about 450 million m3, 1669: about 650 million m3). A few of the flank eruptions were quite explosive and built large pyroclastic cones, like Monte Nero during the 1646-1647 eruption and Monti Rossi in 1669.

The last eruption in this series, in 1669, apparently emptied a shallow magma reservoir that had existed throughout the previous decades - evidence for such a reservoir lies in the presence of abundant up to centimeter-sized plagioclase feldspar crystals in the lavas of all eruptions from 1600 until 1669. The rounded shape and pale yellow color of these crystals has led the locals to call the lavas of this period "cicirara", which means something like "chickpea lava", because the crystals resemble chick peas! Due to a prolonged presence in a reservoir relatively close to the surface, the magma could cool and crystallize to the degree that plagioclase grew to the "chick pea" size crystals seen in the 17th century lavas. Further evidence for wholesale magma extraction from a shallow reservoir and a dramatic withdrawal of the magma column in the central conduit is the collapse of Etna's summit cone during the 1669 eruption (Corsaro et al., 1996).

After the 1669 eruption, Etna has never again produced "cicirara". Furthermore, the frequency and size of flank eruptions dropped sharply for about 100 years, with only three minor flank eruptions being recorded in 1689, 1702, and 1755. It seems that the magma reservoir that had fed the intense activity of the 17th century had disappeared, the feeding system of the volcano had been disrupted, and the mountain had become structurally stable. Much of the time, all magma that made it to the surface rose to the summit, where a new cone was constructed. Flank eruptions became frequent again from 1763 on, and for the next 100 years occurred about once per decade, with volumes of a few tens to rarely more than 100 million cubic meters per eruption.

Interestingly, throughout the 18th and the first half of the 19th centuries, there are no records of significant earthquakes in the unstable eastern sector of Etna as those of the 1980s and of 2002 and the following years. A powerful and destructive earthquake in 1818 near Acireale was probably caused by movement along a regional tectonic fault, not by movement of Etna's unstable flank.

Etna's unstable eastern to southern flank sector, and a selection of earthquakes presumably caused by movement of this unstable sector. Note that there have been many more earthquakes in this area during the period since 1865, when the first of these events took place. Unpublished figure by Boris Behncke

Then came the year 1865, which brought a large eruption on the northeast flank - the Monti Sartorius eruption - and soon after its end, a very localized, extremely shallow (close to the surface) earthquake on Etna's eastern flank, which devastated the village of Macchia di Giarre and killed about 70 people. Similar earthquakes have since then occurred at a recurrence rate of a few years, luckily rarely resulting in as many fatalities, but often causing significant damage and a few human deaths. Most, if not all, of these earthquakes are now known to be related to slippage, or movement, of Etna's unstable eastern to southern flank sectors.

At the same time, the intervals between flank eruptions have become systematically clustered into determined sequences, or parts of cycles. The first cycle started after the large 1865 flank eruption (and the first earthquake in modern time that can be with confidence attributed to flank displacement), initially with quiet emission of gas from the Central Crater and a few years later, mild activity within the Central Crater. From 1874 until 1892 there were five flank eruptions, which showed an overall increase in emitted volume in time, the latest - in 1892 - being the most voluminous (besides 120 million m3 this eruption also produced a significant amount of pyroclastics). This increase in the volume of flank eruptions was apparently the result of increasing structural instability of the volcano. Apparently the emission of a large volume of magma brought this cycle to a close, the volcano returned to relatively stable conditions, and a new cycle started, like the previous one, with a period of quiescence, followed by summit activity, which in turn was followed by a further series of flank eruptions. Four cycles of this type occurred between 1865 and 1993. The latest of these was longer than its predecessors - 42 years - and culminated in a series of no less than 13 flank eruptions, many of which were among the largest of the past 300 years. This cycle ended with the 472-days-long eruption that lasted from December 1991 until March 1993 and produced the greatest lava volume - about 250 million cubic meters - of any Etnean eruption since 1669.

Evolution of the 1952-1993 eruptive cycle at Etna, showing three main phases (Eruptive quiescence -> summit activity -> flank eruptions, ending with a particularly voluminous flank eruption). Unpublished figure by Boris Behncke and Marco Neri

Interestingly, there was very little seismic activity in Etna's unstable sector during the first two phases of this cycle, whereas they became more and more frequent during the third phase. Many episodes of accelerated flank displacement preceded flank eruptions by days to months, as in 1981, 1983, 1985, and 1989.

Etna's latest and ongoing cycle started after the end of the large 1991-1993 flank eruption. For two years, no eruptive activity occurred anywhere on the mountain. Then, in summer 1995, eruptive activity returned to the summit craters - first at the Bocca Nuova and then at the Northeast Crater; in 1996 and 1997 also the Southeast Crater and the Voragine joined the party (Allard et al., 2006). This period of summit eruptions continued until July 2001 and consisted of several long-lasting lava overflows and more than 150 episodes of violent Strombolian to sub-Plinian explosive activity, nearly always with copious lava emission. We called this exceptional period of activity "The Millennium Fireworks". Still more exciting fireworks came with the flank eruptions of 2001 and 2002-2003, and two more flank eruptions have occurred in 2004-2005 and 2008-2009, separated by a period of spectacular eruptions from the Southeast Crater in 2006-2008. These events are described in detail in the Bulletins of the Global Volcanism Network (scroll down the page to get to the more recent reports).

What should be noted is that since flank eruptions kicked in again in 2001, the unstable flank sector of Etna has moved at sometimes astonishing rates (up to several tens of centimeters in a few days in spring 2009), and seismic activity in this sector has been intense, including a series of rupturing events at the Pernicana fault as recently as April 2010. The volcano seems to be currently in the middle of an eruptive cycle, and it is likely that this will come to an end (and bring back the volcano to a state of temporary stability) only with a very large, voluminous flank eruption (Behncke and Neri, 2003a; Allard et al., 2006). From a scientific point of view this is rather exciting. From a human (and civil defense) point of view, these prospects are rather disconcerting and challenging.

So why does the flank of Etna move? It is now believed that much of the movement is caused by the pressure of magma accumulating within the volcano. As a matter of fact, much more magma enters into Etna's plumbing system than exits during eruptions. The quantity of this unerupted "excess" magma can be approximately calculated from the amounts of gas emitted from the volcano, in particular sulfur dioxide. It has thus been revealed (Spilliaert et al., 2005; Allard et al., 2006) that at least three-quarters of the magma that enter into the Etnean feeder system stay there, which leads to a constant volume increase. Where does all this magma go? There are certainly no empty spaces that can host this magma, so space must be created, and this is best done in pushing the volcano, both upwards (so that the volcano swells, or inflates), and sidewards, in whatever direction the side of the mountain gives way most easily. At Etna this is on the eastern, southeastern, and to a lesser degree, southern flanks, which are not buttressed by surrounding mountains as the northern and western flanks. It can be speculated that the more magma accumulates below the volcano, the more unstable it becomes, and this in turn facilitates the opening of fractures on the flanks, allowing magma to escape in flank eruptions. Possibly the presence of a large, relatively shallow magma reservoir during the 17th century led to a strong destabilization of the volcano, which thus had magma leaking through its open flanks on any given occasion, and in large volumes. A similar situation seems to be on the way to become established in recent decades - so no one would be really surprised to see Etna behave again like it did between 1600 and 1669, but once more, these are anything else than comforting prospects.

eklemetti Wed, 08/18/2010 - 00:14

Tags

Very interesting.

I was just wondering, is a catastrophic flank failure at all likely?

Outstanding work Dr. Behncke! Thank you so much for publishing this to the impressed hobby-volcanologists!

"...much more magma enters into Etna's plumbing system than exits during eruptions."
This is, to me, a stunning revelation.
1. Do you believe that a massive failure of the southeastern slopes could take place, in a similar way as it did in Mt. St. Helen's?
2. Is ice accumulation, in winter, heavy enough to affect the stability of big fat Mamma Etna?
3. If you pick Etna and covers it with a huge Icecap (like in VatnajÃ¶kull, in Iceland) what would happen? Could we compare processes in Badarbunga system with Etna's?
It's getting more and more interesting and enlightening.
Thank you Boris.

@Gareth #1 and Renato Rio #3 - currently a catastrophic flank failure seems unlikely, because the stress on the eastern flank sector is released in numerous small slip episodes and nearly continuous, slow, aseismic creep. This is similar to the flank slip at Kilauea, and some publication (I admit I don't remember which one) recently proposed that basaltic volcanoes such as Kilauea, Etna, and Piton de la Fournaise are capable of accomodating their flank instability in numerous and frequent minor episodes rather than collapsing catastrophically. Obviously, catastrophic collapse does occur (it is well documented for the Hawaiian volcanoes and the Valle del Bove collapse at Etna seems pretty much ascertained by now) but more rarely.

Ice and snow accumulation are currently relatively minor at Etna - virtually all snow melts during the summer - but minor quantities of ice can be preserved under tephra if this is deposited on snow during the winter as in early 2000 and late 2002. The quantities of ice do not appear to be significant in affecting the volcano stability. However, a few thousand years ago this might have been different - a group of British scientists (Deeming, McGuire and Harrop) recently proposed that the Valle del Bove collapse was triggered by magma intrusion into water-saturated flanks during cooler and wetter weather conditions.

We know that Etna was covered with glaciers before the cataclysmic "Ellittico" eruptions 15,000 years ago. The presence of the glaciers certainly led to much more explosive volcanism than has occurred since then. However, this is an area of ongoing studies and much more needs to be revealed.

Boris,

I lived on Etna (in Nicolosi) from 1993 to 1996. I was able to witness it "re-awaken" from its slumber following the huge 1989-1993 lava eruptions. I used to go up to the fractures produced by the initial 1989 intrusions which cut the roadway to the ski area (as I remember!). At times, while I was at the fractures, the guardrails would abruptly begin to creak and pop, I believe due to further intrusion and spreading going-on beeath that area. so i had my own makeshift strainmeters! Upon returning to my home, following one particularly noisy/active visit to the fractures, the Northeat Crater erupted!
By the way,...another outstanding presentation of your knowledge of Etna volcanology!

Thank you Boris,especially for the information about flank stability. It never even crossed my mind that Catania on the sea may be in a fault/slip zone.

What an amazing volcano.

Stupendous.

Boris,

that was a fantastic presentation! I was watching some of what was going on, too, and that made it all the more interesting for me to read. I can hardly wait for the next installment! I can see why you chose to study Etna because it is a facinating mountain with some interesting seizmic zones along with the volcanic mechanisms.

From the illustration of Behncke and Neri (2003b) it looks like some fault blocks on the north-east area and I am wondering if it is part of the flank collapse or fault blocking.

I remember the quake that offset the roads and did so much damage and watched as the Piano de Lago disapeared. That was such a beautiful area before the eruption that covered so much of it. But there is beauty even in the lava flows just like the area around Mt. St. Helens and Mt. Lassen. It is amazing how things can recover so quickly and something else that I have found interesting is the fact that around Mt. St. Helens, there has been fossilization found already! I think that has blown the scientific world's mind. I will look forward to the day when some recovery will be evident in the Piano de Lago area. It will take a while, but I bet it will come back faster than we ever thought possible. Of course, it depends on Etna's activity. It could send more lava down that way.

Has there been any indication of an eruption taking place any time soon? Maybe you will be talking about that in your next post.

Thanks so much for taking the time to teach us about Etna and the complexities of the inner workings of a volcano not fully understood. Interesting stuff.

just a random thought ...

a large active sill type magma chamber extension in the E / SE would have a very high "lubricating" effect on the movement ? no ??

sort of like trying to walk on a sea of ball-bearings ???

I am in awe..I feel like saying "we are not worthy". Almost reluctant to ask what are probably rather silly questions, but:

Re the 'chick-pea' lavas: surely basalt magma held "in storage" for some time would first crystallise olivine? Are there olivine phenocrysts? Or did this mineral sink under gravity, so that somewhere in Etna's guts there are olivine cumulate lenses? (left after the bulk of that magma body had erupted)

Second: I read a while back (in a press story, so a dubious source) that recent Etna lavas had been found to contain amphibole, for the first time in many years. Is this so, and is it related to the recent changes in behaviour?

Third (more relevant to part 1, sorry); how does the historically active Campi Flegrei del Mar Sicilia (sp?) SW of Sicily fit into the plate-tectonic scheme for the Etna/Sicily area?

#10 @Mike Don
Your third question also came to my mind. I was curious to understand the tectonics under both Campi Flegrei Mar Sicilia and Pantelleria. The latter is explained as being "continental rifting" (!?)(SMI Global Volcanism Program)but they don't mention any correlation between the two volcanoes. Could Campi be a continuation of Calabric Arc? Could there be another segment of subducting oceanic lithosphere underneath? Or another "slab rollback" to the W? I have been doing some research over the web, but all I could find was this abstract from an article concerning the Lipari-Vulcano Volcanic System (LVVC):

"...the LVVC crustal structure and the evolution of the volcanism are consistent with those recognized in zones of transition from arc-related to rift volcanism. In addition, results of a preliminary mechanical analysis based on the available structural data indicate low values of the ratio between magmatic overpressure and tectonic stress. This suggests a passive mechanism of mantle upwelling. The mantle upwelling is due the post-collisional normal strikeâslip tectonics affecting the Aeolian Arc."

http://www.sciencedirect.com (link to big to be pasted)

Since the LVVC is further NE I don't know if has any relation to Campi and Pantelleria, both only 70 km apart.
When Boris said "the geodynamic setting of Etna is a bit complicated" he really meant it.
Any clues, Boris?

@Mike: I also found a very interesting book on the subject through Google Books:
"Postcollisional tectonics and magmatism in Mediterranean region and Asia, by Yildirim Dilek,Spyros Pavlides (you can read parts of it):
Here's a transcript:
"These features collectively suggest that the fault pattern observed in the Sicily channel may result from coexistent deformation regimes, with NE-SW-directed extension superimposed on the subduction-related NW-SE-directed compression in the Maghrebides (?), Sicily and the Apenines. The case history of the Sicily channel indicates that continental and extensional processes can overlap in the same area. Moreover, the coexistence in this central Mediterranean area of two deformational settings suggests that plate boundaries are passive features rather than the driving mechanisms of plate tectonics."
Isn't that awesome?

I'm still trying to get my head around just how big this volcano is.

http://i34.tinypic.com/2n9jl34.png

@Lurking
Fantastic plot! You can almost see the magma pushing up through the "slab-rollback-created-window". And yes. It is huge. Good job!
I suggest that everyone tried some Google-earthing over Sicily. And also over Pantelleria. Don't miss the pictures attached - you can see the most extraordinary rock formations near the southern edge of the island.
And then you all understand why Boris is so happy in this geological paradise.

Okay... I have more faith in these profile quake plots.

View North

http://i33.tinypic.com/8ys4dz.png

View East

http://i38.tinypic.com/2mq0pow.png

Note how the quakes tend to veer off to the East as they get shallower. (compare the two views)

View North is one degree across, View East is 0.5 degrees across.

#15 You mean, like in an ascending helical? Interesting...

Fantastic article, Boris, thanks! When will you write the definitive book on Etna?

@Lucky #13: what strikes you as odd about the topology?

Other Etna data graphs of interest:

1. Using the Volume vs Time chart, if one goes to the Wikipedia Little Ice Age entry and captures the past portion of the temperature plot (1600-2004) and superimposes a semi-transparent image over the TvV chart, very nice correlation may be found in the rate change over time.

2. Using the 'example of a cycle' chart, and superimposing upon it a portion of the 'Global Temperature Record' (also a wikipedia graphic), again, we see an interesting correlation between phases and temperature.

So what is going on here? We got a hint, in Boris' comment above, that one of the phases of activity *may* be correlated to Ice Age recession of Etna glaciers at existed during the Dryas period of icecap recession.

We think temperature glacier rebound, centered just below Switzerland where large icecap fragments once existed and glacier recession is much in evidence, and change in Mediterranean sea level during recent hemispheric cooling (LIA, within the last 400 years) might be factors at work in 'loading' aesthnosphere window flow to the magma chamber, with corresponding flank fissure periods during record warm periods.

If the window aperture were relatively narrow, the adjacent plate flexure may explain sensitivity to continental isotactic shift and through changes in sea floor pressure.

Conjecture of course, but interesting correlations nonetheless. If this were true, it might provide a basis for modeling past events and predicting activity cycles as a function of climate and sea-level change.

I wouldn't exactly call that helical. A bend, yes... but I don't think a helix from that small amount of data. (2009 to like... two days ago)

I did see a helix pattern in some of the EyjafjallajÃ¶kull quakes, but I can't tell you what it means... other than being an interesting fracture pattern.

#19 Yes, I recall having seen that pattern elsewhere too, that's why I mentioned it. Maybe there isn't enough length for a full helix to develop, or maybe magma isn't fluid enough to let it go, but it looks like, for my amateur eyes, after so many plots of crust and mantle features, that there's always this twisted shape in most instances, whatever they be, faults, quakes or rising magma. Comes to my mind another discussion upon its vortex-like behavior. (??!!!)

That's the idea of the blog!
Learning more and more. I hope in the future an article of the different types of volcanic quakes (VT, LP, HB, etc.) to know what they mean, not only the abreviations, but the physical interpretation.

Boris,

Thanks Boris, I'm looking forward to part 3. I was on Etna in october 2009 and returned in july this year, I never realized that Etna is such a huge volcano. The pit at the foot of South-East crater was intermittently steaming vigorously. http://picasaweb.google.nl/ptibben/EtnaSicily#5507022110941199874

@Renato Rio, I did my master's project on Pantelleria last year. It is in an extensional setting despite the overall tectonics being compressional, which surprised me to begin with. GPS studies show that the western tip of Sicily is moving slightly more eastwards than Tunisia, leading to E-W stretching in the Sicily Channel. Paleomag also shows Sicily has rotated clockwise. Why this should be happening, though, I never did find out; I was measuring CO2 output so it wasn't really relevant. Boris may know more, he did write a paper on it, after all...

After the past week of non-stop earthquakes around the world this quiet trend that has been going on for the past few days almost feels like the calm before the storm.

Thanks again, Boris. You've given us such an amazing resource. Non-scientists almost never have access to graphics like these, with descriptions and analyses written in non-scientific English. I'll come back to this again and again.

@24 Haven't really noticed a quiet trend, then again haven't really paid attention. However I have noticed the sun's activity has quietened down from what is was the last few months. I'm not making any connections here just an observation.

@26 Chris, Did you see the solar eruption yesterday that happened on the far side of the sun, it was a blast which produced a C4-class solar flare and hurled a bright coronal mass ejection (CME) over the sun's western limb?

http://www.spaceweather.com/swpod2010/18aug10/cme_c2_512.gif?PHPSESSID=…

I look at the solar weather site too, it is possible that the magnetic storms could effect more that we think.

Thank you, Boris! My knowledge is by far not good enough to understand everything but I still very much enjoy reading your great texts! Keep it coming, please :-).

Renato 11/12: Thanks for these references. it looks like the western end of Sicily is as complicated as the east (and thanks for that to Gareth too) I wonder if the CFdMS activity has some relation to that curious kink in the plate margin down the west of Sicily (diagram from Boris' link to Highly Allocthonous) We really need Boris on this one.

An ability to visualise in three dimensions is vital for geologists..it's something I'll have to re-learn :o(

Gareth: more please sometime on Pantelleria, it's one of those forgotten volcanoes that no-one ever mentions

@Gareth:
Thank you for the update. It is becoming clearer now.
@Mike don:
Thanks for bringing up the question. It was a fascinating piece of research.

@23, Gareth: this citation answers your question on the clockwise rotation you mentioned in your comment.

Structural evidence for Neogene rotations in the eastern Sicilian fold and thrust belt. Monaco and DiGuidi (2006)
J Struct. Geol. 28(4):561-574.

>From a geodynamic point of view, the Neogene clockwise rotation in the eastern Sicily fold and thrust belt is related to the regional framework of the AfricaâEurope convergence.

Historical Etna flow diagram from Dr. Behncke's post draped on Google Earth (3D) with roadways enabled. 3 x vertical exaggeration.

http://i37.tinypic.com/8ygcvq.png

@27 R.Hurst Yes I saw that. Pretty cool stuff. Seeing the sun build up to some high activity for the last few months and now showing some low activity again is a bit of a let down, almost anticlimatic. I was hyped up over all the sun activity then I read about 3 X-class solar flares that were directed at earth in 2005, I think it was, and really had no adverse effects besides some nice aurora's further south. Also I'm waiting to see if we get more swarms at yellowstone in the dec/jan time frame.... sorry to diverge from the Etna topic at hand.

@33Chris, A great site to see a dozen pics of the real-time sun each with a different filter is

http://www.solarmonitor.org/index.php

I made a mistake posting the sun comment on the Etna topic, I was aiming for the summer thread #2, sorry everyone.

I really enjoy reading about Etna Boris, I brought up this page at home and my 14 year old son saw your write-up. On Discovery channel last month we watched a show on the most dangerous volcanoes in the world and Mt.Etna was featured, lets just say that he was very impressed, you are a great writer Boris.

Lurking, master of charts could you do on on the activity at VatnajÃ¶kull?

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Etna Week (Part 1) - Brief Anatomy of an Exceptional Volcano

eklemetti — Mon, 16 Aug 2010 03:58:11 +0000

Etna Week (Part 1) - Brief Anatomy of an Exceptional Volcano

Etna Week Part 1

Mount Etna - Brief Anatomy of an Exceptional Volcano
By guest blogger Dr. Boris Behncke.

Italy truly deserves to be called "the Cradle of Volcanology" - not only because it hosts virtually all existing types of volcanoes and volcanic rock compositions, and seven of its volcanoes have had confirmed eruptions during the historical period (i.e. the past approximately 2700 years), but also because the earliest surviving eyewitness account of an eruption was written in Italy, the first volcano observatory and the first geothermal power plant were built in Italy, and three volcanological terms denoting styles of eruptive activity - Strombolian, Plinian, and Vulcanian - have their origin in this country. The word "volcano" itself has its origin from the southernmost of the Aeolian Islands, in the Tyrrhenian Sea north of Sicily, Vulcano. Vesuvius, uncomfortably close to Naples and its very densely populated suburbs, is possibly still the most famous volcano worldwide, and certainly one of the most dangerous volcanoes on Earth.

Snow-covered Etna seen from the village of Trecastagni, on the southeast flank of the volcano, in January 2008, taken by Boris Behncke.

In this exceptionally varied volcanic setting, Mount Etna on the island of Sicily is a volcano of superlatives. It is the most active volcano of Europe and - after KÄ«lauea on Hawai'i - possibly the second most active volcano on Earth, in terms of eruption frequency and long-term average magma output rate. It has the longest record of documented eruptions of all volcanoes worldwide, and can be said to be virtually continuously active, with significant eruptive events occurring almost every year. Its summit stands at 3330 m elevation as of 2010 (Neri et al., 2008), making it the tallest mountain in the Mediterranean basin, and the highest summit in Italy to the south of the Alps. Besides the four nearly continuously active craters at its summit, Etna has approximately 350 craters and minor vents on its flanks, each of which erupts only once, and many of which form sizable cones, like miniature volcanoes, on the flanks of the mountain.

But what makes Etna really unique is its incredible versatility in terms of eruptive styles, eruption magnitudes, and eruption locations. During the historical period, it has produced numerous effusive, Hawaiian to Strombolian style eruptions from vents both at its summit and on its flanks, sometimes purely effusive activity going on for years, countless short-lived episodes of violent Strombolian to sub-Plinian fire fountaining accompanied by voluminous lava and tephra emission, Vulcanian and phreatomagmatic explosions and persistent ash emission sometimes lasting for months (Branca and Del Carlo, 2005). This record is punctuated by a Plinian eruption in 122 B.C. (Coltelli et al., 1998), which caused devastation and hardship to the population of Catania, a city that had been founded more than 600 years earlier by the Greek at the southern base of the volcano. Pyroclastic flows, the most lethal and destructive of all volcanic phenomena, have been observed on a number of occasions in recent years, but luckily affected only the remote summit area (Behncke, 2009).

In spite of its frequent and sometimes violent and hazardous activity, Etna has claimed a surprisingly small number of human victims - less than 80 deaths can be with certainty attributed to the activity of the volcano in the past 2700 years. This figure might be higher because the historical record contains several gaps up to a few hundred years long, like the Arab domination from the 9th to 11th centuries A.D. (all Arab records were lost during the Christian recolonization); yet it is clear that Etna is not a killer volcano, and this is one of the reasons why the people living on its slopes call it "the friendly volcano".

Geological setting and evolution of Etna
Like all things in Italy, the geodynamic setting of Etna is a bit complicated. For this reason, the origin of Etna has been ascribed by various workers to subduction, rifting, and a mantle plume, and more recently, some more exotic factors.

Sicily lies on the boundary between two converging (or colliding) lithospheric plates, the African plate to the south and the Eurasian plate to the north. This convergent margin runs across much of the Mediterranean along a general east-west trend, but shows a marked bend in Italy, where it turns NNW up to the Alps before taking on a SE trend in the Balkans toward Greece. Differently from many convergent plate margins, where one plate consists of oceanic and the other of continental lithosphere (like in the Pacific Northwest of the U.S. where the oceanic Pacific plate runs into, and dives underneath the continental North American plate), the colliding plate margins in Italy are heterogeneous, with bits of oceanic lithosphere alternating with continental lithosphere. The character of convergence therefore changes over short distances from subduction, as in the Calabrian and Aegean arcs, to mountain building as in northern Sicily and along the Apennines and the Alps.

The volcanoes of the Aeolian Islands are believed to be, at least in part, due to the subduction of oceanic lithosphere of the Ionian Sea under the Calabrian arc. However, rather than consistently erupting calc-alkaline magmas as subduction-related volcanoes commonly do, the Aeolian volcanoes also produce more sodium and potassium-rich magmas, which some scientists attribute to magma melting at different depths along a very steeply dipping subducting lithospheric slab (Tommasini et al., 1997).

While out in the Ionian Sea, to the east of Sicily, the northern margin of the African plate consists of oceanic lithosphere subducting underneath the Calabrian arc, on the island itself it is constituted by rather thick continental lithosphere, which makes up the southeast corner of Sicily. Rather than subducting, it bites and pushes into the continental lithosphere of the southern margin of the Eurasian plate. The result is mountain building - much like in the Himalayas or in the Rocky Mountains - going on in the Peloritani, Nebrodi, and Madonie mountain belts, which together constitute the northern backbone of Sicily. Etna lies just north of the plate boundary and away from the Calabrian arc subduction zone, in a rather uncommon place for a volcano to occur, plate tectonically speaking. For this reason, some researchers have invoked a hot spot origin of Etna, and of the older volcanic area of the Monti Iblei to the south, where volcanism has occurred over more than 200 million years (Schmincke et al., 1997; Tanguy et al., 1997; Behncke, 1999). Schiano et al. (2001) present arguments for a transition from a hot spot origin to a more and more pronounced subduction component in Etna's magmas. However, the hot spot model is not plausible because volcanism has shown a northward shift from the Monti Iblei to Etna, which would require movement of the African plate to the south, whereas in reality the contrary is the case (the African plate is moving northward).

Interpretative sketch of the geodynamic setting of Mount Etna, based on Gvirtzman and Nur (1999). From Armienti et al. (2004)

A series of recent publications (Gvirtzman and Nur, 1999; Doglioni et al., 2001; Schellart, 2010) places Etna into a context of slab rollback related to the subduction of Ionian oceanic lithosphere below the Calabrian arc. Slab rollback means that the bend where an oceanic plate starts descending into subduction moves gradually away from the subduction zone due to the weight of the subducting plate, and consequently it sort of tears the subduction zone and the overriding plate into the direction of the subducting plate. In the case of the Ionian plate subduction this would mean that the subduction zone migrates southeast, which is well illustrated here at Highly Allochthonous. This leads to the tearing open of a gap between the subduction setting of the Ionian oceanic lithosphere and the Calabrian arc to the east, and the continental collisional setting of Sicily to the west, which in turn causes decompression and the formation of magma in the upper mantle below this opening gap, or "window". The magma rises along the intersection of a number of major regional fault systems and feeds the activity of Etna.

Whatever the geodynamic cause of Etna, it appears to be highly efficient. Throughout its roughly half-million-years-long history, Etnean volcanism has become more and more vigorous and increasingly focused on a large volcanic edifice, eventually leading to the building of the large mountain that dominates Sicily today. The geological evolution of Etna is subdivided into four main phases: (1) the Basal Tholeiitic phase, (2) the Timpe phase, (3) the Valle del Bove centers phase, and (4) the stratovolcano phase.

Geological map of Mount Etna, from the INGV-Catania web site (courtesy of Stefano Branca). Key: (1) Recent alluvial deposits; (2) Mongibello (past 15,000 years) eruptive products (2a) "Chiancone" volcaniclastic debris deposit; (3) Ellittico eruptive products; (4) Valle del Bove centers eruptive products; (5) Timpe phase eruptive products; (6) Basal Tholeiites; (7) Sedimentary basement; "Faglia" = fault, "Orlo della Valle del Bove" = Valle del Bove rim; "Crateri Sommitali" = Summit craters

Distribution of eruptive products of the four main phases of volcanism in the Etna area: (a) Basal Tholeiites; (b) Timpe phase; (c) Valle del Bove eruptive centers; (d) Stratovolcano phase. From Branca et al. (2004)

(1) Basal Tholeiites. The first phase of volcanic activity in the Etnean area occurred about 500,000 years ago, in an area then occupied by a broad bay - referred to as the pre-Etnean gulf - leading to the emission of submarine lava (pillow lava) and associated debris, which is known as hyaloclastite. Some eruptive events lasted long enough to build small volcanic islands, much the same way as the island of Surtsey formed in 1963-1967 off the south coast of Iceland. Outcrops of these earliest products of Etnean volcanism occur along the coast of the Ionian sea immediately to the north of Catania, in the area of the fishing villages of Acicastello and Acitrezza. The castle rock of Acicastello is a world-class geological site (unfortunately not placed under protection as it would certainly deserve) where pillow lavas can be seen next to a typical breccia of small glassy fragments (hyaloclastite) and debris of shattered pillows (pillow breccia or flow-foot breccia).

The spectacular outcrop of Acicastello, on the coast of the Ionian Sea at the southeast base of Etna, where the earliest eruptive products of the volcano (Basal Tholeiites) are exposed. The left (western) part of the outcrop consists of densely packed pillow lavas, whereas breccias of shattered pillows and hyaloclastite (fragments of volcanic glass altered into yellowish-brown palagonite) make up the right portion of the section. Photos by Boris Behncke.

The products of this earliest phase of volcanism in the Etna area are tholeiitic basalts - virtually the same magma that is currently being erupted from KÄ«lauea (Hawai'i), which is the reason that this phase in the evolution of Etna is referred to as "Basal Tholeiites". Besides the outcrops of Acicastello and nearby locations such as Acitrezza and Ficarazzi, products of this phase occur also further to the west, near the town of Adrano at the southwest base of the volcano.

(2) Timpe phase. The second main phase of Etnean volcanism occurred between >220,000 years ago and about 110,000 years ago in a narrow belt along the Ionian coast along a fault system known as the "Timpe" (the steps). The Timpe faults are marked by conspicuous morphological scarps, and terminate to the NNW near Moscarello and Sant'Alfio on the east flank of Etna. During this phase, numerous fissure eruptions occurred in this relatively restricted elongate belt along the Ionian coast, and led to the growth of a NNW-SSE elongated shield volcano about 15 km long. The internal structure of this shield volcano is today exposed in the Timpe fault scarps between Acireale and Moscarello. During this eruptive period, sporadic volcanism also occurred along the valley of the Simeto river, constructing, amongst others, the large scoria cone that constitutes the hill of PaternÃ² and a number of thin, strongly eroded, lava flows like those cropping out in the northern periphery of Catania at Leucatia-Fasano. The products of this phase showed a shift from tholeiitic to alkali basaltic compositions.

(3) Valle del Bove eruptive centers. About 110,000 years ago, the focus of volcanism shifted from the Ionian coast into the area now occupied by the Valle del Bove. In this period, the character of Etna's activity underwent a profound change, from sporadic fissure eruptions as during the first two phases, to a more centralized activity of both effusive and explosive character. This activity led to the construction of the first composite volcanic edifices in the Etna region, the Rocche and Tarderia volcanoes. The products of these eruptive centers crop out along the base of the southern flank of the Valle del Bove at Tarderia and Monte Cicirello. Subsequently, the activity concentrated in the southeastern sector of the Valle del Bove, at Piano del Trifoglietto, where the main eruptive center of this phase was built up, Trifoglietto volcano, which reached a maximum elevation of about 2400 m. Three minor eruptive centers formed subsequently on the flanks of Trifoglietto, which are named Giannicola, Salifizio and Cuvigghiuni; their activity continued until about 60,000 years ago. This phase marks the formation of a stratovolcano structure in the Etna edifice and the superposition of different eruptive centers.

(4) Stratovolcano phase. About 60,000 years ago, a further shift in the focus of eruptive activity toward northwest marks the end of the Valle del Bove centers, and the start of the building of the largest eruptive center of Etna, now named Ellittico (the elliptical), which constitutes the main structure of the volcano. The Ellittico volcano produced intense effusive and explosive activity, constructing a large edifice, whose summit may have reached a height of 3600-3800 m. Numerous flank eruptions generated lava flows that reached the Simeto river valley to the west of Etna. About 25,000 years ago, the Alcantara river was deviated from its former valley closer to Etna (in correspondence with the towns of Linguaglossa and Piedimonte Etneo) into the present-day Alcantara valley (Branca, 2003). Much of the Ellittico lavas and pyroclastics are present in outcrops in the northern wall of the Valle del Bove.

The tan-colored clastic rocks in these photos are the pyroclastic-flow deposits emplaced during the climactic explosive eruptions at the end of the Ellittico stage of Mount Etna, about 15,000 years ago. These deposits occur in outcrops near the town of Biancavilla on the lower southwest flank of the volcano. Photos taken in August 2001 by Boris Behncke

The Ellittico stage ended about 15,000 years ago with a series of powerful explosive (Plinian) eruptions (Coltelli et al., 2000), which destroyed the summit of the volcano leaving a caldera about 4 km in diameter. Intense eruptive activity continued during the past 15,000 years, largely filling the Ellittico caldera, and building up a new summit cone. This current summit edifice is called Mongibello. About 9000 years ago, a portion of the upper east flank of Etna underwent gravitational collapse, generating a catastrophic landslide (the Milo debris avalanche), and forming the huge collapse depression of the Valle del Bove, which still today bites deeply into the eastern sector of the volcano (Calvari et al., 2004).

Aerial view of the Valle del Bove, a huge collapse depression formed by a massive sector collapse of Etna's eastern flank about 9000 years ago. Much of the depression has been filled by more recent lava flows; the original depth must have been significantly greater. This view is from the southeast, showing the summit craters in the upper center. Photo taken in August 2007 by Boris Behncke

Following the Valle del Bove sector collapse, remobilization of the debris avalanche deposit by alluvial processes led to the generation of a detritic-alluvional deposit, known as Chiancone, which crops out between Pozzillo and Riposto along the Ionian coast. This huge collapse of the eastern flank of the Mongibello edifice has exposed a large portion of the internal structure of both the Valle del Bove eruptive centers and of the Ellittico volcano, which crop out in the walls of the depression. The eruptive activity of the Mongibello is strongly controlled by structures of weakness in the volcanic edifice, where most intrusions occur along a number of main trends.

These predominant trends are characterized by three main rift zones, the Northeast, South and West rift zones. Although much of the activity of the Mongibello volcano is effusive, numerous strongly explosive events are known as well, mostly from the summit craters (Coltelli et al, 2000). The most powerful eruption of this eruptive phase occurred in historical time, in 122 B.C. (Coltelli et al., 1998). This eruption, which occurred from the summit of the volcano, produced a large volume of pyroclastics (ash and lapilli), which fell in a sector on the southeast flank of the volcano, causing heavy damage in the city of Catania.

(Part 2 to follow later this week.)

eklemetti Sun, 08/15/2010 - 23:58

Tags

Thanks, Boris Behnke, for this interesting and clear explanation of the Mt. Etna.
Bevor I came on this blog I didn't realise that here in Europe we have " real" volcanos und how interesting they are!
Looking forward to Part 2.

Hello Boris Behncke, thank you,this is great stuff, especially for this neophyte who has been training on the EyjafjallajÃ¶kull eruption! Lots of information clearly expressed and building on what we have already learned. Looking forward to the next installments.

Etna is ... huge.

I am amazed at how much detail has been gathered about the history of the volcano. But when you conciser the size, there is probably a lot of information to be found.

Great article.

Terrific write-up on Etna Boris! Thank you for bringing us "up-to-date" on current thoughts about the history and behaviour of la Etna!

Thanks folks - and there's quite a bit more to follow later this week!

In the meantime Sicily's geodynamics continue to be alive. This afternoon (16 August 2010) we had a magnitude 4.6 earthquake in the Aeolian Islands, the epicenter being near Vulcano island. There has been damage to buildings and infrastructures on Lipari, Vulcano, and Salina, landslides, and 7 people have been reportedly injured.

No way saying whether this earthquake is related to Vulcano, which last erupted 1888-1890.

Some more info at www.flickr.com/photos/etnaboris/

Approximate timing of Etna's eruptive phases appears to correspond to Northern Hemispheric IceAge mass changes.

See Temp Figs, Sediment Records (temps) and pattern of temperature and IceAge volume changes, section on Glacials and Interglacials.

http://en.wikipedia.org/wiki/Ice_Age

Of particular interest is the timing of 100KY climate cycles, at ~500KY, where benthic O-18 shows large fluctuations.

Expanded map showing the collision interface between African and Eurasian plates.

www.uwgb.edu/dutchs/GeolColBk/BW/AfricanPlateBW.gif

Thank you, Boris, for the interesting first installment of Etna info. Sounds to me as if Sicily and the surrounding area is just about as complex as Island. I am still trying to wrap my head around slap rollback. I think I have an understanding of it, but I am not sure so I will be reading that again to see if I can make sense out of it. From the interpretative sketch, it looks very complicated and the geo community is really not all that sure what is the cause of Etna's activity because it "isn't supposed to be there" sort of thing.

Thanks for posting a picture of the Valle de Bove because that has given me a perspective of what that area looks like and where the lava flows were going in 2006. That was the time my DH and I watched the Etna Treking cam for six hours! That was awesome.

I look forward to your next post to learn more. You know, I miss your reports that you used to do on you web site. So much has changed!

Yay.... I found data.

INGV Centro Nazionale Terremoti

cnt.rm.ingv.it/earthquakes_list.php?year=2010&month=12&ml_selection=0

Gathered all quakes from 2010 to present and plotted.

View north

http://i34.tinypic.com/29cx3ie.png

View East

http://i35.tinypic.com/x411sl.png

Note: This plot goes down to 600 km, which is about 20 times deeper than my Icelandic plots.

And a zoomed in perspective view. Colors adjusted to reflect shallower depth limits.

http://i37.tinypic.com/10xfz21.png

Boris, what (if any) significance is there about tholeiitic basalt being the first eruptive products of etna, changing to alkalic?

Does it imply more of a mantle component in the initial products?

Also, given the large amount of melt that rises through etna, has there been any thought about whether the area might be prone to hosting a shallow magma chamber? What leads to that sort of thing? Is it a more diffuse area where intrusions take place vs the established magma path to the surface that etna posesses?

Boris' website page on Etna References, per citations referenced in his Etna introductory material.

http://boris.vulcanoetna.it/ETNA_references_ac.html

Passerby (#11) rightly noted that there were no references in this first Etna bit - they will come with the third part (I placed them at the end of the whole thing I submitted to Erik). So with a few days of patience you'll also get the whole bunch of references (there are many recent ones included, which are not on my old "Etna references" page) ...

Stay tuned.

Meanwhile, we're getting the happy information that today afternoon's M 4.6 earthquake near Vulcano has, as it seems, not caused any injuries to people. However, it's the Big News tonight in Italy, though there's a tendency to downplay a little bit on the side of Lipari's administration, we're at the apex of the tourist season!

@Lurking [8-9]
I think you just got your coordinates wrapped around your head... ;)

This should be on East longitude, ie. increasing from left to right when viewing North, and a northward plot should show longitudes, while the eastward plot has lats growing from right to left.

(Yeah, me too: the same head all the year round...)

Funny thing: when I started typing this comment, the keyboard was Chinese - never happened before; English pops up rather often, but this was the first spontaneous Chinese pop-up.

It's possible. I generated two of them when I saw the issue, I may have linked the wrong one. I'll go check.

err....

"increasing from left to right"

Which one are you looking at? That's what I'm seeing. "View North" has the low numbers on the left (west)

The "View East" has north to the left (high numbers)

If you are seeing something different please let me know.

@Lurking -
Woops! My bad (partially); what you have are mixed longitude/latitude texts.

Thanks, Boris for an informative look at Etna and its effects on the area surrounding it. I only wish I had read this before when I went up to Etna in 2006 and saw the lava flow from the 2003(?) eruption. It looked like the beginning of a 4 lane asphalt highway leading down from the summit almost to Linguaglossa (one lucky town). I was in Acireale. I wish I had known about the geologic area of Acicastello. For anyone interested in volcanoes their impact on culture and history, Sicily is a great place to visit.

I'm a fan of the INGV webcams. When are they going to fix the Stromboli webcams? And would you explain the thermal imaging webcam and what that is supposed to be telling us. I understand the thermal webcam for Stromboli but not the one for Etna.

Fantastic article Boris I enjoyed reading it.
Now what are the chances of you resuming the updates to Italy's Volcano's???? An excellent site and I've had withdrawal symptoms since you stopped updating it.

Thanks for the article Boris. Its very interesting to read.
Have you ever considered writing your own blog about Etna and whats going on there? Something like the style of your Flickr Postings today. I think there would be interest for it.

@Kultsi, Askola, FI

Okay, now I see it. The labels are backwards.

I'm currently working on extracting terrain data for Etna/Sicily in order to get a better view. I'll be correcting those labels then... if I don't decide to lash out at the guy who coded this PoS Ladserf software package in Java. (It should not take this long to save a [expletive deleted] file).

Boris, thank you for the discussion chock full of wonderful nuggets about Etna. I have to admit, I'm still a beginner, and it will take me longer to fully appreciate your information. I'm adding it to my "to read after more study" file. ;-)

@Dr. Boris Behncke
Never thought it could be sooooo interesting and enlightening to go through your article, specially the geodynamics part. I got stuck, like Diane, around the "slap rollback", but for what I could understand, it provides a very reasonable explanation which is not "mantle-plume"-related. The idea of a "window" tearing that subducting slab is amazing. It's like "rifting" in the middle of a subduction boundary, if I got it right. And Lurking plots show deep focus earthquakes typical for subduction zones, which denies the "hotspot" version.
I've been to Italy many times and my friends always wanted to drag me to Sicily, and I declined it for other historical locations, but next time this won't happen. Thank you very much indeed!

#9 #13 @Lurking
I've noticed the shifted labels too. Your plots go N through all Italian volcanoes and seismic zones up to Firenze, I think. Which makes it very interesting, because you can "see" magma rising to Stromboli, Vesuvius, etc.

M 4.5 - SICILY, ITALY - 2010-08-16 12:54 UTC
http://www.emsc-csem.org/Earthquake/earthquake.php?id=184125#maps

#20 @parclair
I forgot to thank you for the amazing link on Lake Kivu's methane harvesting, on the other thread. Very good "mood-stimulating" effect to me.

Thanks, Boris, my wife went to Etna when she visited back in the 70's. Erupting then. Amazing system.
Would like to see it and Sicily sometime...

Okay... a redo. Been fighting and cursing the terrain extraction program most of the day.

This is a pretty wild view, not real pretty, but its all of Sicily with the quakes planted under it. Perspective view.

http://i36.tinypic.com/2lxayde.png

And these two are closer in views with the terrain of Etna plotted over top of it.

Copy paste these two. (the forum monster will get me if I make them into links)

i38.tinypic.com/smrpya.png

i36.tinypic.com/5k38ki.png

Caveat: If I have hosed up the lat-lon labels again, I'm going to go out back and kick something.

Re: #25
Hydrothermal vents rising from the same aesthenosphere source, under Sicily?

Mount EtnaâIblean volcanism caused by rollback-induced upper mantle upwelling around the Ionian slab edge: An alternative to the plume model. Schellart (2010) Geology.

http://geology.gsapubs.org/content/38/8/691.abstract

#25 @Lurking: You did it again! Latitudes are supposed to be between 36Âº and 38Âº and longitudes between 12Âº5 - 16 Âº. :)

Well, then prove that this one is wrong...

http://i35.tinypic.com/dximu1.png

Plan view.

The North-South and East West things are just right. Good job!
BTW what was that spoofing all about on the other thread?

Some one was using my moniker and posting stuff using it. I noticed that they put some URL in their sig. I didn't follow it since it's usually some advert when the Intruder Bots strike. A lot of times it's a script that wanders around to make random but believable posts to drum up traffic or customers.

It looks like Katla is starting to stir again this morning, it seems that the activity is going in waves starting on the North fault line and slowly moving South, it almost seems that the fault line has a pulse.

http://en.vedur.is/earthquakes-and-volcanism/earthquakes/

Wow.... Etna rocks...!!

As a Frenchman, I don't get too often my fix of active volcanism (or I would have to go to La RÃ©union, which would be interesting by the way ;), and I'm absolutely delighted to have such a volatile neighbor not too far away... (unless it does what Eyjaf did this spring and grounds every aircraft for two weeks..)

Kudos to Boris Behnke for such a master piece of information.... To everybody who run this blog, Keep on the good work!!

Now, for everything to go insanely cool, I would love to have it erupt.... Oh nothing big, just the pyrotechnics we all know and love, without disturbing anything nearby!

@RH #32... check the depths. All 1km. Nothing to remotely get excited about it!

Boris;

love these articles, but could we get access to higher resolution images, please

Thanks;
Robert Somerville

WOW! I am amazed at how much detail has been gathered about the history of the volcano. But when you conciser the size, there is probably a lot of information to be found.

A wonderfull articles you have written here, I know a little bit about Etna when I was a master degre student and visited Etna in 2001. I have seen one unexpected eruption then I was in Sommitali crater, dangerous but stronger than a real thriller. Therefore, after your explaination, I now understand some detail better than in 2001.

A advised man staleness skin a move of revenge without tantalising foolery

Could the developer of this site contact me a.s.a.p - I may be able to help you out.

Welcome to Etna Week!

eklemetti — Mon, 16 Aug 2010 03:57:12 +0000

Welcome to Etna Week!

Italy's Mt. Etna erupting in November 2006.

Well, I am currently off in the wilderness, but that doesn't mean that things aren't still hopping here at Eruptions. We are lucky to have Dr. Boris Behncke of the INGV Catania as that blogger and he brings us a three-part series on Mt. Etna on the island of Silicy. That means this week is Etna Week here on Eruptions, so for all of you chomping at the bit for more information on the Italian volcano, you are going to get it (and then some).

modern-day satellites who can watch that same summit from space.

I think you're all going to love this series, so I'll thank Boris now for his great work. Enjoy!

eklemetti Sun, 08/15/2010 - 23:57

Tags

@Erik @Boris
This blog is similar to soap operas in Brazil: once you see the first chapter you get addicted. You guys should be in the entertainment business.
Just coming back from work to my daily checking of volcanic news (all quiet over Iceland) and you give us Etna! And introducing it with the most fantastic picture.
Good grief!
I have papers to write, but I'll just get a snack and read through the main page.
Amazing blog! I'm so happy to be here.
Thank you!

Heh, better than Shark Week! on the Discovery Channel.

@Boris:
Congratulations for the beautiful family you have.
I saw the picture of your daughter (http://www.flickr.com/photos/etnaboris/) playing with sulfur on Etna's slope and I remember that when I was a kid my mom used an old Portuguese formula ("talco Granado") to sooth our skin rashes. It consists of a mix of talc and sulfur and happens to be an excellent antiseptic and deodorant, specially for parts of the body exposed to heavy sweating. The patent was bought by Johnson & Johnson, and I don't know if it is commercialized elsewhere. Still today I use it as a dry deodorant (it has a slight sulfur smell but it proves to be excellent for feet and armpits).
I must say I was happy to find out that Etna has a low lethality history (only 84 in historical registers), otherwise I would be worried for your family safety. But the landscape and the volcano itself are stunning , so I assume you people must have a a wonderful time living in the shade of Mama Etna.
Looking forward to more information on this amazing volcano.