Volcano Research

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

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)

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…

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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 3) - Etna's Volcanic Hazards

eklemetti — Fri, 20 Aug 2010 02:05:36 +0000

Etna Week (Part 3) - Etna's Volcanic Hazards

The final part of Etna Week, brought to us by guest blogger Dr. Boris Behncke. Check out Part 1 and Part 2 as well!

Etna Volcanic hazards
By guest blogger Dr. Boris Behncke.

Etna is one of the most active volcanoes on Earth, and a population of nearly one million people dwell on its flanks, many in areas that have been repeatedly invaded by lava flows during the historical period. A few villages have been constructed very close to the vents of eruptions only a few hundred years old.

Top: Residential areas surrounding numerous pyroclastic cones on the lower southeast flank of Etna, seen from Monte Arso, a cone that erupted in the late Middle Ages looking toward the metropolitan areas of Acireale and Catania. The cones seen in this image are all prehistoric but just outside the field of view are a few cones that erupted during the past 2000 years. Photo taken in 2000 by Boris Behncke. Bottom: A volcanologist's dream and nightmare - one day, a new crater will open and grow into a new cone in our backyard, like shown in this apocalyptic photomontage (the big cone formed during the 2001 south flank eruption projected onto a photograph of my hometown Trecastagni on the southeast flank of Etna). Both original photos by Boris Behncke

As mentioned before, few people are known to have lost their lives due to eruptions of Etna. During the last century, three deadly incidents are known, in 1929 (two deaths), 1979 (nine deaths), and 1987 (two deaths); in all cases the victims were visitors to the summit crater who were surprised by sudden steam-blast (phreatic) explosions. Amazingly, many people have escaped unscathed during a number of much more violent explosive magmatic eruptions, which, however, always showed a conspicuous buildup for some time before culminating. In contrast, phreatic explosions occur virtually without warning, as has been tragically demonstrated at Galeras volcano (Colombia) in 1993, when nine people, including six volcanologists, were surprised and killed by a relatively small explosion - they happened to be near the very crater (some were even within the crater taking gas samples). [For further detail on the Galeras incident, there are two rather gripping and contrasting stories, "Surviving Galeras" written by one of the survivors, Stan Williams (in collaboration with Fen Montaigne), and "No Apparent Danger" by former-geologist-turned-into-reporter Victoria Bruce'. I recommend to read Williams first and then Bruce, after which you may be having some sort of a balanced view of things.]

Volcanic hazards at Etna are: (1) lava flows, (2) tephra falls (and volcanic ash plumes endangering air traffic), (3) earthquakes related to eruptive activity and magma movement, (4) volcanic sector collapse, (5) tsunami, (6) pyroclastic flows.

Lava flows are by far the most common hazard at Etna. About half of Etna's historically recorded eruptions have caused damage to human property due to lava flow invasion. In most cases the losses have been cultivated land, but on a number of occasions buildings have been destroyed. More rarely have population centers been impacted and partly or completely destroyed - during the past 400 years this has happened only three times, in 1651-1653, 1669, and 1928.

Etna eating towns and villages - luckily this happens quite rarely. Top image is a reproduction of a fresco exposed in the sacristy of the cathedral of Catania, which neatly shows the erupting vent (Monti Rossi) low on the south flank of Etna and the lava flow being diverted around the city of Catania by its city walls; people can furthermore be seen fleeing on boats, others holding processions, and a few housewives hanging their laundry next to the hot lava to make it dry faster.

In a recent study, Behncke et al. (2005) for the first time tried to quantify the risk posed by lava flows, diving the Etnean area into six different zones of increasing hazard, from the coastal areas to Etna's summit. This work revealed a moderately high risk of lava flow invasion in a densely populated area on the southeast flank of Etna, including Trecastagni where I and my family are living. However, such hazard zonation is of relatively limited use for land use planners and civil defense, since the boundaries of different hazard zones are relatively vague and do not reflect the morphological variations of the terrain on a scale of a few tens to a few hundreds of meters.

Mapping the lava flow hazard at Etna. Top image shows the rough subdivision by Behncke et al. (2005) into six hazard zones, bottom image renders a much refined impression of the vulnerability to lava flow invasion based on the SCIARA lava flow simulation model (Crisci et al., 2010).

A much more sophisticated effort was thus launched in recent years, which involved several groups of scientists from various universities in Italy and abroad, and the Istituto Nazionale di Geofisica e Vulcanologia. I participated in some of this work, and the results are encouraging. The main means of defining the hazard from lava flow invasion, and fine-tuning the hazard zonation and the vulnerability of the Etnean area at very high resolution, is computer simulation of lava flows. Different models have been applied at Etna for the simulation of lava flows, which are described in much detail in publications by Crisci et al. (2010), Favalli et al. (2009), and Herault et al. (2009).

It is now possible to recognize those areas that would be impacted first - obviously those lying in morphologically low areas - and where to concentrate rescue efforts and salvage operations once the location of an imminent or starting eruption is known. The tens of thousands of computer simulations carried out during the project have not only served to produce very detailed hazard maps for Etna, they also produced virtually all possible eruption (lava flow) scenarios for any location on this volcano. These scenarios can be extracted with a few mouse clicks on demand, so that simulating new scenarios causing loss of precious time will not be necessary.

The risk of damage and disruptions caused by tephra fall has been seriously underestimated at Etna until recently, mainly due to the (false) notion of Etna being a non-explosive volcano. During the about 150 episodes of lava fountaining during the 1995-2001 "Millennium Fireworks" at the summit craters, heavy showers of ash and scoria (very porous, black, centimeter-sized fragments of lava) occurred frequently on the flanks of Etna, causing damage to crops, and sometimes breaking car windshields and disrupting road traffic. During one of these episodes, on 26 April 2000, a passenger airplane starting from Catania airport with more than 100 passengers on board encountered the tephra plume and falling scoria cracked its windshield, whereupon the airplane had to return for an emergency landing in Catania. Since that incident, air traffic is severely restricted during explosive eruptions at Etna.

This became a particularly biting issue during the prolonged ash falls from the 2001 and 2002-2003 flank eruptions, and again during the 2006 summit eruption. For periods of days to weeks, the airport of Catania remained closed, sometimes even the airport of Reggio Calabria, on the Italian mainland about 70 km northeast of Etna, had to be closed as well. For this reason, people in Sicily were not particularly shocked when Iceland's EyjafjalljÃ¶kull brought all air traffic in Europe to a grinding halt in the spring of 2010 for a few days, including northern Italy.

The revelation that ash-producing flank eruptions are far more common at Etna than previously thought indicates that the population around Etna and people travelling from and to Sicily in airplanes will experience further disruptions due to ash falls about once every 10-20 years. Obviously, tephra falls will be locally devastating if a flank eruption occurs close to the populated areas, as in 1669. A similar event would bury the villages to the east and southeast - including Pedara, my home town Trecastagni, Mascalucia, Tremestieri, and a few more - under up to several meters of tephra. In this moment, I know of no preparations for such a case, and educating the public (administrators and inhabitants) to create an awareness of this and other hazards is overdue.

Earthquakes accompanying the movement of magma or caused by magma-induced flank displacement are frequent on the eastern, southeastern, and southern flanks of Etna, and often cause significant material damage and occasionally kill people. Such events cannot be predicted, and prevention such as earthquake-resistant construction is essential. Building codes are applied for new constructions since the 1980s, but an amazing quantity of residential buildings as well as hospitals and school buildings were constructed during the 1960s to 1980s without applying any codes, so that a tremendous number of such buildings are vulnerable. This is an issue of unimaginable proportions, and extends far beyond Etna's magma-related seismic activity, because all of eastern Sicily is a high-risk seismic zone due to the presence of several major regional tectonic fault systems, and a number of large population centers such as Catania and Messina lie in this area, having a building stock of which maybe 20 per cent would resist (not collapse) during a major earthquake.

Volcanic sector collapse is known to have occurred at least once during the history of Etna, about 9000 years ago, forming the Valle del Bove. This event is believed by some researchers to have caused a massive tsunami, which ravaged the coasts around the eastern Mediterranean (Pareschi et al., 2006). Although the flanks of Etna continue to be severely affected by instability, the risk of a major sector collapse and related tsunami is currently considered low.

Pyroclastic flows are a fairly new discovery at Etna, although this volcano has proved more inventive in different mechanisms to generate such flows than any other volcano. I have had the doubtful privilege to witness small pyroclastic flows in the summit area of Etna on two occasions, in 1999 and 2006, and at very close range (less than 1 km), and a few colleagues have made similar experiences. These flows were showing nearly all the characteristics of pyroclastic flows on other, generally more explosive volcanoes, but were - luckily - very small and some apparently were much cooler than their more common counterparts.

Pyroclastic flow caused by the collapse of an oblique eruption column from the Southeast Crater, on 16 April 2000. Note the numerous people near the building in the left foreground, immediately after this photo was taken they fled downslope, and no one was touched by the flow. Note the large pyroclastic fragments in the air above the pyroclastic flow. Building is Torre del Filosofo, which was buried under tephra during the flank eruption of 2002-2003. Photo courtesy of Jean-Claude Tanguy, published in Behncke (2009).

During the past 25 years, small pyroclastic flows have occurred on at least 10 occasions in the summit area and on the upper flanks of Etna. A few were caused by collapse of eruption columns, which is one of the most common mechanisms of pyroclastic flows worldwide. A fine example of this type occurred on 16 April 2000 at the Southeast Crater, when a heavily charged pyroclastic jet shot out obliquely from an opening flank vent, the heavy downpour of gas-charged fragments developing into a pyroclastic flow that passed a few hundred meters from dozens of spectators, luckily without reaching any of them. Similar events occurred in 1986 at the Northeast Crater, repeatedly during the numerous lava fountaining episodes from the Southeast Crater in 2000 (and possibly also during similar events in early 1999), and more recently, on 10 May 2008 and on 8 April 2010.

A very different scenario was the one we encountered on 25 October 1999, during the one-month-long eruption that filled the Bocca Nuova to overflowing (Behncke et al., 2003). On that day, magma pushing through hot, though largely solid material filling the crater, uplifted a portion of that material, raising it like a lava dome and thrust it over the crater rim onto the steep outer flank of the central summit cone. The flank of this dome-like mass steepened, becoming unstable and collapsing like the flanks of a growing silicic lava dome, much the same way as the lava domes of SoufriÃ¨re Hills on Montserrat or Merapi in Indonesia. The collapsing masses of hot, gas-charged rock transformed into small pyroclastic flows that traveled at a speed of about 70 km per hour, and some of us were just a few hundred meters away from these flows.

Ground and aerial views of the small pyroclastic flows that formed during the Bocca Nuova eruption on 25 October 1999. These flows were generated by the collapse of a mass of hot lava, which was pushed from inside the crater over its western rim. Note the vigorous Hawaiian-style lava fountains in both images. Photos by Marco Fulle (top) and Marco Neri (bottom)

The most impressive pyroclastic flows seen in recent years at Etna were those of November 2006, and they were also the most enigmatic in terms of the mechanisms which generated them. On 16 November, during one of many eruptive episodes at the Southeast Crater between July and December 2006, lava issuing from the summit of the cone interacted explosively with wet, hydrothermally altered rocks into which it was eroding, causing numerous small and two larger (up to 1.5 km long) pyroclastic flows (Behncke et al., 2008). Different interpretations of the causes of the larger flows were proposed by Norini et al. (2009) and Ferlito et al. (2010), the earlier proposing a purely gravitationally induced collapse of the cone (the pyroclastic flow was in fact described as a debris avalanche by Norini et al., 2009), the latter envisaging a sudden decompression of shallow magma when the cone's flank collapsed. These scenarios fail to take into account that removal of a significant portion of the cone was not an instantaneous event but occurred over more than 6 hours at a rather slow speed, a process that I and numerous colleagues had observed since early on that day. But whatever the details of the causes, the pyroclastic flows were large enough to engulf people had they travelled southward rather than southeastward. The temperature was probably low, because plastic-coated wooden signs placed along a tourist path had not suffered any heat effects, but the mechanical impact might have been deadly for any living being in the path of the pyroclastic flows.

Dramatic sequence of photos showing development of a large pyroclastic flow from the southeastern base of the Southeast Crater cone on 16 November 2006, photographed from about 1.5 km to the south. The first photo (upper left) shows the initial explosive jets that generated the flow, consisting entirely of ash, blocks, and water vapor, but little incandescent material. The abundance of water vapor indicates involvement of a large volume of wet, hydrothermal-fluid-soaked rock, which mixed and interacted explosively with hot lava flows. Building visible in the first three frames is what remains of Torre del Filosofo, largely buried under 2002-2003 tephra. Photos courtesy of M. La Rosa

Similar pyroclastic flows occurred on 24 November and were again observed at close range by a geologist (Robin Campion from Belgium), but no study of the deposits and on the triggering mechanisms was carried out in this case.

Finally, a fourth mechanism producing pyroclastic flows was discovered during an episode of lava fountaining and emission of voluminous, fast-moving lava flows from the Southeast Crater on 29 March 2007. In this case, a large lava flow encountered deep snow on a steep slope, and apparently disintegrated as snow melted and failed under the moving lava; this caused powerful explosions which in turn produced pyroclastic flows and mudflows that advanced for about 1 km downslope into uninhabited areas.

As far as can be understood from current knowledge, pyroclastic flows as those observed in the past few decades are a severe hazard for visitors to the summit area, but do not threaten the lives and property of the people living on the slopes of Etna. However, larger pyroclastic flows were generated during the cataclysmic eruptions at the end of the Ellittico stage about 15,000 years ago, and during the 122 B.C. Plinian eruption. Chances of an Ellittico-style event are extremely remote, because the magma composition is different today, but an event like in 122 B.C. cannot be fully excluded to occur even in the short term.

Much, much more could be told about Etna - such as the relationship of the volcano with the people who live next to it, and the various monitoring techniques now being applied by the Istituto Nazionale di Geofisica e Vulcanologia of Catania, as well as a number of groundbreaking research efforts. It would be well worth to indicate how Etna can be discovered by volcano and nature lovers without beating the common tourist paths. All this may come in a future guest blog - and, obviously, one day there will be a new eruption to inform you of. We are all waiting for it - hoping that we will still have a peaceful summer and maybe a peaceful Christmas, and a peaceful next year. One day time will run out, and be certain that you'll receive the news firsthand here on this blog.

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Neri, M., Acocella, V., Behncke, B., Maiolino, V., Ursino, A., Velardita, R. (2005) Contrasting triggering mechanisms of the 2001 and 2002-2003 eruptions of Mount Etna (Italy). Journal of Volcanology and Geothermal Research, 144: 235- 255, doi: 10.1016/j.jvolgeores.2004.11.025

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eklemetti Thu, 08/19/2010 - 22:05

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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?

Hello.This post was really motivating, particularly because I was investigating for thoughts on this subject last week.

Amazing points. Going to want a bit of time to ponder the info=D

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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.

GVP's Sally Kuhn Sennert answers your questions!

eklemetti — Fri, 13 Aug 2010 02:49:04 +0000

GVP's Sally Kuhn Sennert answers your questions!

Earlier this summer, we had a chance to ask Sally Kuhn Sennert of the Smithsonian Institution/USGS Global Volcanism Program questions about her job as the main writer of the well-loved Weekly Volcanic Activity Report. Well, now here are the answers!

Sally Kuhn Sennert of the Global Volcanism Program in front of Mt. Rainier, Washington.

Q&A Sally Kuhn Sennert:

Q: Could you describe how you go about putting together the weekly update?
A: If time permits, I would start to gather information on Friday when particular sources post their weekly summaries. The majority of the information gathering, however, actually happens on Monday mornings, when I visit about 40 websites. I also rely on reports coming to me via email either directly from the source (like from Rabaul Volcano Observatory) or indirectly through news feeds. I read the source information and write reports for most of Monday and Tuesday, often revisiting sites for updated information in the process. On Wednesday morning, I check a few more sites and then pass the "finished" Weekly Report to colleagues. The Report then goes through two rounds of editing by two of three regular Weekly Report editors in the Global Volcanism Program. In the meantime, I prepare the website files, such as the interactive map. If everything goes smoothly, the Report should be posted around 4 PM on any given Wednesday! Whew!

Q: How do you differentiate between reliable and unreliable sources?
A: I consider THE authority to be the folks at individual observatories and therefore the reports they produce. I also utilize the notices from the multiple Volcanic Ash Advisory Centers (VAACS). News reports are also important, especially when there are no other sources. With the media, I try to only use major sources, such as Reuters or Associated Press, and I use them carefully! Once in a while, one of the sources gets something wrong (analysts initially thought plume seen in satellite imagery was from volcano- later discovered it was from forest fire) or I misinterpret a translation, and a correction has to be posted in the report. That is the nature of the "rapid reporting" of the Weekly.

Q: Do you get a lot of "tips" from people about volcanic activity that is happening?
A: Funny thing about that- on a few occasions now, I have learned about eruptions I had no clue about from my grandma or mom!! In my defense, they are events that happened on weekends, when I am tuned out. Yeah, that's my story.

Q: What would make your job easier in terms of getting a complete picture of activity?
A: Definitely visiting more volcanoes!! It is so much easier getting the big picture of an event if you have been there and know the layout of the land or have seen the previous eruption products first hand. I would also love to meet more volcanologists (esp. folks at the observatories) around the world. Familiarity with people you communicate with is so important.

Q: How do you see the reports changing in the future? What about the GVP in general?
A: As the world becomes more digital, GVP has lost some of the personal connections with contacts that have really strengthened the monthly Bulletin, the database of activity, and to some degree the Weekly in the past. People used to call in or fax information, but now, observers can just post reports on their own blogs or websites! We are in the process of really reconnecting with people and fostering better information exchange. We are also continuing to improve our website and how we communicate to reach as many people as possible. For the Weekly specifically, I would love to see better maps available for each volcano- perhaps something 3-D and interactive.

Q: Have any new social networking sites like Facebook or Twitter made your job easier or harder?
A: Both! It is important to keep up with the current communication technology and methods; if you want to get your information out there, you have to do it in the way your audience prefers. The downside is that I can't keep up! My grandma and I share this complaint.

Q: What sort of questions do you get at the GVP from the general public? How about the media?
A: Public questions vary depending on the interests of the individual asking the question. GVP recently participated in the Smithsonian's Folk Life festival and showcased what we did. Questions from the public varied from why the "African Plate" is named the Nubia Plate to what was the magnitude of an earthquake that happened in the questioner's hometown on the day they were born. Questions like these, and seeing the wonder on people's faces when you talk about volcanoes or geology in any form, make it all worth it. Most of the questions from the media come during an eruption and center on trying to get us to predict when it will stop. Enthusiastic reporters are always fun to talk to, no matter what they try to make you say!

Q: Is there any way the general public can get involved with helping the GVP, the weekly reports or the website?
A: YES! GVP hosts several volunteers that work on the Bulletin reports, if you're interested drop me an email. We also welcome reports of volcanic activity from anyone that will send them, either volcanologists doing fieldwork or the casual vacationing observer. We do need specific information to incorporate the information into a report, such as date of observation or where the observer was. The more info the better! Many of our reports of volcanic activity "in the middle of nowhere" come from a recreational sailor passing by or a hiker on an adventure. I often ask, if a volcano in the ocean erupts and no one is there to see it happen, did it? A later random floating pumice raft may have the answer.

Q: What volcanic event of the last few years was the most interesting to follow?
A: The eruptions that stand out in my mind are from Jebel at Tair (2007), Nevado del Huila (2007), Kelut's dome growth (2007), ChaitÃ©n (2008), Sarychev Peak (2009), and finally the 2010 EyjafjallajÃ¶kull eruption. All of these events were new, exciting, important, and fun to follow.

Q: What else do you do for the Global Volcanism Program and/or the Smithsonian Institute/USGS?
A: My current high-priority "other project" is to write film scripts. I am helping my Global Volcanism Program colleagues create short educational films based on our historic film footage archive that we are currently digitizing. Several will be available on-line very soon, and in multiple languages.

Q: What is your favorite volcano?
A: I have to pick only one? That is tough! My default favorite (from grad school days) is PopocatÃ©petl, specifically because of the fabulous existence of "Popo Cam", but when I really think about it, I have to say Kilauea. It is such an interesting and accessible volcano! People from all walks of life, all ages, all backgrounds and interests can go there, hopefully at the right time, and have an experience of a lifetime. I lucked out when I participated in a field school and got to stand on cooled lava flows while watching (and feeling the heat of) new Earth being born right in front of me. I will never forget my time there, and probably never again eat a burrito as good as the one I cooked on an incandescent crack.

Q: How do you determine which volcanoes are listed in the active category versus the ongoing category (each week)? (From Diane; Stephen in the UK)
A: There is a page called "Criteria and Disclaimers" that discusses the topic of your question (http://www.volcano.si.edu/reports/usgs/index.cfm?content=disclaimers). Even though the reasoning behind the category assignment seems straight-forward, there are some volcanoes or some eruptions that don't quite fit the mold. So I sometimes consider the assignment on a case-by-case basis. For instance, I reported seismic swarms (no eruption) at Melimoyu in mid-June 2010. That volcano has never been reported on in the Weekly or the Bulletin, as it has only two documented eruptions in the Holocene. I assigned it to the "New Activity/Unrest" section to draw attention to it simply because it has not been reported on before. There are other volcanoes that have periodic or "typical" seismic swarms that I don't include in the weekly at all.

Q: Why are there sometimes unfinished or outdated information on the Global Volcanism Program website? (from Jon Friman)
A: The only area that may seem "unfinished" that I can think of is the Geologic Summaries written for each volcano. They are occasionally written in a way that does not accommodate new activity, and need to be re-worded. They, along with some other areas of the website, get updated yearly. As far as "outdated," one of the main goals of GVP is to database and archive information about volcanic activity over the last 10,000 years. We are currently archiving data from volcanoes active in the Miocene as well. So, by design the archived information is "outdated!"
Seriously, if you see something on the website that seems incorrect, unfinished, or just leaves you scratching your head, please email me and I will certainly look into it.

Q: Why was the recent large eruption at Redoubt 2008-2009 removed from the list of larger Holocene eruptions? (from Riggs)
A: I am not aware that it was there and removed. The list of large Holocene eruptions consists of volcanoes with VEI eruptions classified as 4 or higher. Perhaps the Redoubt eruption in question was thought to have been a 4 or higher at first and then changed to a 3 once the activity and products were better understood.

eklemetti Thu, 08/12/2010 - 22:49

Tags

Global Volcanism Program

Q&A

Smithsonian Institution

@Erik Klementti:
We are most honored to have Sally Kuhn Sennert answering to our questions. Hope she will continue doing her wonderful job and that we may someday be able to provide some contribution from here. And hope she comes back again.
Looking forward to see the new improvements to the GVP site. It will be great to have 3d maps and footages to illuminate our volcanic discussions.
Thank you Sally and Erik!

I've obviously missed the opportunity to forward a question and I would like to make up to that.

I would like to know why a continuous red status volcano like ChaitÃ«n is left out of the report.

Thanks in advance for answering my question and the opportunity to ask questions in the first place.

Great opportunity, continue the good work.

And maybe we should thank her for another recent improvement to the GVP site: a vastly increased photo archive for many of the world's volcanoes

I'd like to thank Sally and everyone at the GVP for the weekly report. I always look forward to Wednesday afternoons!

Also, to echo mike @ #3, the GVP recently added thousands of volcano photos to the site.

Keep up the good work!

OT: For everyone that could answer. A volcano classified as a 'caldera' could be a 'stratovolcano' at the same time?
Because I think there are stratovolcanoes that have a caldera only as a morphologic feature caused by an individual eruption.

For stratovolcanoes that have calderas as well look no further than two of the largest eruptions of the last two centuries: Tambora and Pinatubo. Both volcanoes now have a substantial caldera but both also retain enough of a peak to still be a stratovolcano as well.

OT, a new episodic tremore slip (ETS) initiated in the northwest a few days ago. These events happen every 14 months or so and it was only a few years ago that seismologists figured out how to tease the tremor signals out of the background noise. The tremor seems to be associated with non ductile shearing and/or hydaulic movements in or near the accreationary wedge above the subducting plate. To me this sounds like part of the story of the ongoing uplift of the eastern Olympic mountains, but I haven't yet found a report that identifies if there is a vertical component to the tremor.

Here are two site that track the episode:
the blog, with near daily comments and links to previous events: http://www.pnsn.org/WEBICORDER/DEEPTREM/summer2010.html

the data map, updated daily with tremor location: http://www.pnsn.org/tremor/

Thank you ,Sally for answering our questions. I check the info periodically and I plan to check it more regularly again as I used to. Thank you for the work you do.

@R. de Haan: The ChaitÃ©n status was lowered to yellow a few months ago, although is still moderately active.

Thank you, Sally Kuhn Sennert, for answering our questions. Come back and see us!

Riggs is actually the name of my beagle, as is Sassy, I used them in my email addy.

CHAITEN Southern Chile 2008Â Â MayÂ 2Â 4
OKMOK Aleutian Islands 2008Â Â JulÂ 12Â 4?
KASATOCHI Aleutian Islands 2008Â Â AugÂ 7Â 4
REDOUBT Southwestern Alaska 2009Â Â MarÂ 22Â 4
SARYCHEV PEAK Kuril Islands 2009Â Â JunÂ 11Â 4

http://www.volcano.si.edu/world/largeeruptions.cfm

I read your post very impressed seen this kind of important informationâs. Really am interested to back to your blog again to gather some more informationâs.

I'm Sally's grandma, and LOVED the article she wrote ! Talk about a proud grandma ! Way to go , Sally Sue ! You are special , and much loved !

Hi Sally,
What a wonderful article. I had no idea I had such a smart, talented great niece! Your field has to be very exciting and interesting. Keep up the good work!
Virginia Norris, Fla.

Wow, Sally, I am impressed with all you do. Of course, I don't understand much of it, but I'm impressed nonetheless.
I have such a smart niece!!

What a great article and interesting career you have! I am ERUPTING with envy!!!!

I have been here before but this is among the best blogposts yet. continue the good work!

Odd volcano news: Volcano stadium, wheat from EyjafjallajÃ¶kull and volcanoes as ads

eklemetti — Tue, 10 Aug 2010 09:10:01 +0000

Odd volcano news: Volcano stadium, wheat from EyjafjallajÃ¶kull and volcanoes as ads

August has been rather quiet for real volcano news, but I did find some more, well, odd news to mention. It is all volcano-related - to an extent - so here we go:

The new volcano-inspired Chivas stadium in Guadalajara, Mexico.

Last year we had the volcano mall in Italy, this year we have the volcano football (that is soccer for us Americans) stadium in Mexico (see above). The stadium in Guadalajara has green, sloping sides that that open to the "crater" that is filled with the pitch and the stands - seems fitting for a city in the middle of the Trans-Mexico Volcanic Belt. No word on what happens when the home team scores.
Over in Iceland, EyjafjallajÃ¶kull is being thanked for bringing a bumper crop of wheat to the southern part of the island. One of the wheat farmers, Olafur Eggertsson from Thorvaldseyri, says that he thinks the ash from the eruption helped by adding nutrients to the soil - although the especially warm summer for Iceland this year likely played an important role as well.
And some of you might have seen the news (or the ad) for a new Guitar Hero-like game called Power Gig 2 where the developer supposedly dropped 5,000 Guitar Hero controllers into the crater of EyjafjallajÃ¶kull from an airplane. I've watched the video and I'm 99% sure it is a fake - I mean, it is supposed to be July 2010 when they make the drop, but the "crater" at EyjafjallajÃ¶kull is filled with a partially crusted-over lava lake - which, of course, never existed. So, yeah, I think they spliced in CGI or other video from a lava lake because dropping the controllers into a relatively cool crater lake (of water) wouldn't have the "extreme" edge that the developers were hoping. However, that means that somewhere in Iceland lie the shattered remains of 5,000 fake guitars ... !
And in a less odd and more head-scratching moment - or at least an example of how the media can get things wrong - there is news that Jim Holden of the University of Massachusetts (UPDATE: here is the original NOAA press release, thanks to Passerby) was misquoted as saying he thinks the deep earthquakes underneath Moro Gulf in the Philippines in late July were related to an recently-discovered undersea volcano named Kawio Barat. Now, the article I found doesn't go into details, but the USGS solutions for the earthquakes show focal depths of over 500 km (very, very deep), so for earthquakes like that to be related to an eruption of an undersea volcano would be, to say the least, very surprising. I have a feeling that somehow something go lost-in-translation - the original article in the Inquirer or the NOAA press release doesn't seem to say the same thing.

eklemetti Tue, 08/10/2010 - 05:10

Tags

crater lakes

Volcano Research

http://oceanexplorer.noaa.gov/okeanos/explorations/10index/welcome.html

Erik, I agree about the Philippine quake stories.The first one, from Gulf News, obviously leaps to a conclusion never made by the science crew. Looking at the speculative trash that passes as top news stories on several sites today, this doesn't surprise me.

Here's a news report (in icelandic) on the guitar drop:
http://visir.is/fleygdu-fimmhundrud-plastgitorum-yfir-heklu/article/201…

In short:
They had planned to drop over EyjafjallajÃ¶kull but it was decided to do it over Hekla instead.
The shot of the crater is CG "enhanced".
Two drops of 250 guitars each were performed by firemen from ReykjavÃk.
A rescue service crew on the ground was tasked with picking up the guitars after the drop as a prerequisite for permission.

Bjarni - that makes a little more sense, but by "digitally enhanced" they mean "changed completely to have lava in it. The current Hekla crater is quiet. Nothing like "truth in advertising".

The volcano in the video definitely wasn't EyjafjallajÃ¶kull; the shape was all wrong, for one; there was no glacier, and it should have been spewing steam. The one in the video had fumes rising.

It was an Icelandic plane (DC3?), though, and there might have been 50 "guitars" that they dumped.

The bumper crops were also mentioned in the St. Helens stories a while back...

The NOAA research expedition public website info and a press release got garbled by a reporter who sought to connect the deep-focus EQ activity (many more than 3) in the Moro Gulf with the discovery of the new volcano, by proximity.

Jim Holden is quoted in this NOAA Jul 13 press release, describing the discovery of the new volcano
www.noaanews.noaa.gov/stories2010/20100712_underwatervolcano.html

The Okeanos Explorer US-Indonesia Deep Sea Project Expedition specifics and daily log (with cool graphics, photos and explanations) can be found at:

Really restless today. I expect another EQ to pop up on the map soon.

http://hraun.vedur.is/ja/Katla2009/stodvaplott.html

Sorry for spam posting but can someone explain to me why the 2-4Hz bands has been acting like an equalizer today?

GOD and MID station has been all over the place and these sit on either side of Lady E. MID on west and GOD on east side.

First of all, the item in The Inquirer was not a 'press release'. Both it, and the one in the Gulf News, were "news" reports from obviously science-impaired journalists, who wanted to goose their stories by dragging the recent earthquakes into them. There was no 'garbling' involved. It was out-and-out falsification, since Jim Holden apparently never said one word about the earthquakes in an actual NOAA press release.

Just a comment on the stadium story (haven't had a chance to digest the rest of the post yet). Latin America seems to have a strange link between football/soccer and volcanoes. There is a football pitch in the crater of Guatemala's Agua (according to GVP), and before it resumed activity in the 1980s there was a pitch -of sorts- on the caldera floor of Colombia's Galeras. Can't imagine that the playing surface was much good, probably worse than Wembley (in joke for the Brits on here) Wonder if there are/have been any others?

Erik, you didn't pursue this link //top-10-list.org/2010/01/01/largest-underwater-volcanoes/ in the Kawio Barat-article? Amongst other things, this list informs us that "Heimaey, Iceland" is the world's fifth largest underwater volcano. Funny, at height of some 9,100m (29,855 ft), you'd think that the world's tallest mountain as measured from base to summit, Mauna Kea, would at least get a mention...

*grin*

PS. The summit of Mount Everest is only about 3,650 to 4,650 m (11,980 to 15,260 ft) above the plateaus on either side.

@9 - Yeah, maybe I was hoping that it was just a mistake/mistranslation, but yes, you're probably right that it was a media grab.
@10 - Wow, I'd love to see any info about the pitch on Galeras!
@Passerby - Thanks for the links to the original press releases. I think I'll elevate them to the main text.

'Science' in hindsight

A previously unmapped fault was responsible for the magnitude-7.0 earthquake that struck Haiti on Jan. 12, not the fault originally blamed for the temblor, scientists announced Tuesday.

http://www.ouramazingplanet.com/haiti-quake-new-fault-0434/

Yesterday there was some odd signals in the tremorcharts at http://hraun.vedur.is/ja/Katla2009/stodvaplott.html

They seem to be in some sort of a pattern. I mean MID and GOD charts. This would suggest some sort of manmade noise. Can this be confirmed?

It was mainly the 2-4Hz curves which were affected.

Today it started again and this time it is both 2-4Hz and 1-2Hz.

I am really curious as to what may cause this. Any suggestions?

@14 -
Much more pronounced on MID: starting at 0900 or a bit earlier, break at about noon, another break at 1500, stops around 2000.

I used these plots: http://hraun.vedur.is/ja/Katla2009/oroi_mid.html and http://hraun.vedur.is/ja/Katla2009/oroi_god.html too.

Road works on the road to the boonies just south of MarkarfljÃ³t?

Erik (12): the Galeras reference came from Stan Williams book of the 1993 eruption, 'Surviving Galeras', page 28: "an old wooden soccer goal sits in pieces on the amphitheater floor, placed there by police and soldiers who once played on what was undoubtedly the world's most dangerous soccer field"

@Kultsi #4 - To be exacting, "PÃ¡ll Sveinsson", TF-NPK, is an ex-USAF C-47.

@Raving #13 - Finally we know it wasn't our fault.

@Kultsi #14 - MarkarfljÃ³t flooded today.

Well, that's assuming that anything was ever dropped. Otherwise whoever pulled the stunt should get a huge fine for dumping without a license and they can pay for the mess to be cleaned up as well.

As far as dropping things go, I'm always reminded of Lockheed-Martin dropping a satellite in the integration bay ...

I don't believe there is a lava-lake in ANY icelandic volcano?

And by the way, Guys/Girls - I'm going up there again - leaving from Copenhagen tomorrow morning. After being there for the Fimmvorduhals-eruption at easter this year - I feel an urge to go back and trek across the new lava. Will send you all a thought when standing up there.

Best wishes
Heidi

#19 @Heidi
I don't think there is any lava lake, no.
Wish you a good trip, and please, tell us if hot lava is still present under the solidified new ground.

Cool Heidi! Throw some scoria at the wind for me.

Hey that's an amazing insight on the subject, thanks so much! never heard it more clear.

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The EyjafjallajÃ¶kull eruption and you

eklemetti — Wed, 04 Aug 2010 11:52:58 +0000

The EyjafjallajÃ¶kull eruption and you

EyjafjallajÃ¶kull erupting in the spring of 2010.

I have a request for all of you Eruptions readers! In a few weeks I will be giving a talk here at Denison on the EyjafjallajÃ¶kull eruption and especially the aspects of how the eruption unfolded on the web. I think the shared experience of the seismicity, fissure vent eruption and explosive eruption - along with all the ramifications of the air traffic stoppage over Europe - was a fascinating phenomenon. So, I ask you readers: How would you describe your experience on Eruptions during the EyjafjallajÃ¶kull events? By that I mean in terms of finding information, sharing information, sharing experiences or whatever - what stands out in your mind that made the EyjafjallajÃ¶kull so unique for a volcanic eruption in recent memory, especially in regards to the internet and the blog. Did you feel you got something more out of the collective experience than just following the news events on normal media?

If you are willing and able to share, please send me your thoughts to or leave a comment on this post.

Thanks for any help!

eklemetti Wed, 08/04/2010 - 07:52

Tags

aviation

eruptions

class participation

historic eruption

Volcano Research