Eruptions

Climate, volcanism and the Andes

The northern Chilean and southern Peruvian Andes are full of volcanoes that look stunning – I mean, jaw-dropping details of volcanism litter the landscape. The reason for this is two fold: (1) there is an awful lot of volcanism in the northern Chilean/southern Peruvian Andes (as known as the Central Volcanic Zone) – and has been that way for over 10 million years and (2) it has also been very, very dry in the area (most of which is known as the Altiplano-Puna Plateau) for at least a few millions years as well – it is the home of the Atacama Desert! So, this means you get lots of volcanic eruptions that don’t have to face the rigors of weathering – so the stunning volcanic landforms are preserved. Let us look at an example of this:

Volcano #1: North Sister, central Oregon Cascades
i-1b5cd131b320a9eb2df698b71675eaa0-NorthSister-thumb-400x300-53635.jpg
Click on the image to see a larger version.

Dissected with lava flow and pyroclastic deposit layering along with magmatic dikes exposed. The original flow features are rarely preserved and the volcano’s shape is dictated by glacial erosion. In other words: Beat the heck up.

Volcano #2: Volcan Aucanquilcha, northern Chilean Andes
i-e9dd26334215c21e7fba6c1d64a29cb9-Aucan-thumb-400x246-53637.jpg
Click on the image to see a larger version.

I like to trot Aucanquilcha out for many reasons, but here, notice how you can still seem many of the flow features, especially in the middle – with levees and pressure ridges on the dacite flows. Most of the dacite lava flows are preserved with little erosion to expose the innards of the volcano

Now, lets guess how old these edifices are. Any ideas?
Well, according to work by Mariek Schmidt, the oldest observed lava flows on North Sister are ~400,000 years old, with some volcanic activity as recently as 55,000 years ago – in other words, pretty young, geologically speaking.

Aucanquilcha, on the other hand, has been dated by, well, me, and the youngest flows are potentially ~200,000 years old.There are some features that suggest a few younger than that, but something like 90% of the volcano was constructed between 1.05 million and 600,000 years ago, including those lava flows in the center of the image. So, most of Aucanquilcha was built before North Sister was even started – and North Sister looks much older!

This is (mostly) all thanks to the very different climates of the Cascades versus the northern Chilean and southern Pervuian Andes. Whereas North Sister has had to survive glaciations, wet climates, vegetation, snow and more, Aucanquilcha has mostly lived in a very dry climate, with some minor snow, very minor evidence of glaciation and little precipitation in the form of rain over its history. So, these gorgeous features are preserved at Aucanquilcha, while at North Sister, we get to examine the insides of the volcano – both equally fascinating things to study.

So, why bring this up now? Well, the NASA Earth Observatory posted an image of Sabancaya in the southern Peruvian Andes – and boy, is it dazzling. The lava flows on the volcano look like they might have erupted yesterday, however, a majority of the activity at Sabancaya didn’t happen yesterday (shockingly) – the youngest lava flow dated from Sabancaya is ~5,400 years old. However, the volcano did experience almost constant explosive eruptions between 1990 and 1998 – with small explosions as recently as 2003 – all vulcanian and phreatomagmatic (if you can believe that in the high Andes). The name of the volcano does mean “tongue of fire” in Quechua, which implies that the natives around the volcano had experienced eruptions as well. The lava flows that make up most of the edifice do appear to by Holocene or older, but again, the climate of this area of the Andes has preserved them stunningly, with very obvious levees on the sides of the flow – especially noticeable on the lava on the top center (labeled “lava flow”) and pressure ridges on top of the flow – see the flows directly to the right of the summit. These sorts of images make me pine for the Andes and the ability to see volcanoes preserved like this, although the rarified air of the Altiplano might make up for the lack of thickets.

Comments

  1. #1 bruce stout
    July 26, 2010

    wonderful post Erik!

    Renato posted a link the other day to absolutely stunning photography from the Atacama desert.

    http://www.atacamaphoto.com/atacama/atacama-1.htm

    Highly recommended.

  2. #3 Chris
    July 26, 2010

    off topic – What’s with all the deep earthquakes (500+km depth) in the Phillipines? Does the Asian continental plate go down that far? I thought continental plate thicknesses were only 70 – 100 km thick. Can any geologists hazard a guess as to what’s happening there?

  3. #4 bruce stout
    July 26, 2010

    @ Chris #4

    someone posted a link to this at the weekend:

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

    This will give you a good summary of what’s happening. Go through the last couple of threads here too. There’s been some good discussion on it.

  4. #5 Kultsi, Askola, FI
    July 26, 2010

    Erik,
    Somebody should pull the carpet from under that “Neodymium Magnets” creature; it’s spamming all over…

  5. #6 Henrik, Swe
    July 26, 2010

    As Bruce says, wonderful post Eric! I’ll latch onto the linguistic aspect of volcano names: The native name for Sabancaya Volcano, translated as “tongue of fire” coupled with the visual appearance and the photographic evidence of thick dacite lava flows, possibly hundreds of metres thick (recalling your previous topic on such flows), would suggest the natives actually saw such a flow, hence the “toungue of fire” (coming out of the mouth of the volcano). Do you know if there has been any research of (native) names for volcanoes from a linguistic point of view?

    I would expect the first ojection to such an interpretation to be that the flows are much too old to have been seen and be remembered by humans. Against that I would put forward suggestions made that our legends of giants, trolls and dragons etc have foundations in reality: Giants – (Homo) Gigantopitheucs c 1,000,000 – 300,000BP up to 3m tall and 500+ kg (1000+ lb). Trolls – Homo Sapiens Neanderthalensis, troglodytes extinct c.30,000 BP. Dragons – the dinosaur bone field intersected by an ancient Bedouin trade route through the Sahara, the stories therof brought to us by merchants.

    If there is a connection between the native name and the dacite flows, the implications thereof are very interesting no matter which explanation you prefer.

  6. #7 mike don
    July 26, 2010

    Henrik: I’ve thought of a couple of other examples (not from the Andes, though

    There’s the “other Merapi” in Java -part of the Ijen complex
    Merapi means fire/fiery red, obvious for the famous active one…but the ‘other’ Merapi has no historic eruptions. Its name however surely indicates activity since the Javanese civilisation got started. And famously there’s Mont Pelee, “Bald Mountain”. Unvegetated when named, in an area where eruption products are heavily overgrown within a few decades; obviously erupted only a few years before the French settlers arrived (and had a Carib Indian name meaning ‘fire mountain’)

  7. #8 Diane N CA
    July 26, 2010

    @Dennis, I noticed some comments at the bottom of the report about Gary’s house going up. The first one was obviously somebody who doesn’t understand volcanoes at all. Check it out. I had to laugh a bit and was tempted to set him straight, but decided against it. He doesn’t get it that at the moment, there isn’t any ash with this.

  8. #9 Passerby
    July 26, 2010

    >I would expect the first ojection to such an interpretation to be that the flows are much too old to have been seen and be remembered by humans.

    Huh?? You’re confusing your volcanoes.

    Sabancaya is an andesite/dacitic stratovolcano that has recent (1350, 1695, 1750, 1784, 1986 (start of fumerolic emissions), 1990-1998, 2000, 2003) and is clearly historically active.

    >Until 1990, much of the volcano was hidden from view by a permanent ice field. As a consequence of ash induced melting this ice has now largely been removed.

    ANALYSIS OF SABANCAYA VOLCANO, SOUTHERN PERU USING
    RADARSAT AND LANDSAT TM DATA.

    Aucanquilcha is the dormant Pleistocene-era dacite volcano whose eruption would not have been witnessed by humans.

  9. #10 Diane N CA
    July 26, 2010

    Erik, interesting article. It really shows what happenes according to what the enviornment does to volcanoes and mountains in general. Thanks for posting the contrasts. There is so much to study and so little time. :-D

  10. #11 Dennis
    July 26, 2010

    Hihi Diane, didnt read the comments before, funny thing :), but thanks for the heads up,

    The pictures speaks for itself, that was my intention.

    But another question, how much energy was revealed in the last week with all these quakes? there was this big swarm in Alaska and now this strong deep quakes (3×7) must be a small rise in intensity over the week.

  11. #12 Henrik, Swe
    July 26, 2010

    I quite agree Mike. If we credit the idea that there is some logic behind human name-giving of geographic features, conclusions such as yours seem inescapable. That said, there are examples where the logic isn’t straightforward such as with Himmelsbjerg, “Heaven’s Mountain”, the highest hill of Denmark – which struggles to top 600 ft or thereabouts.

    Passerby, thank you. In my excitement, I did indeed confuse the two as you correctly point out. Unfortunately (for me that is), I cannot claim that Kultsi hacked the Mulakot site as an excuse. ;) ;)

  12. #13 Carl eating Micro-lobsters (Kräftor)
    July 26, 2010

    I must have gotten my brain baked in the sun when sailing. I cannot for my life find the tremor-plots and gps-stationspage for TFZ (Tjörnes Fracture Zombie).
    I wanted to go into the depth with it since it is in the habit of producing nice 3+ quakes nowadays. Anyone with a working brain or a good link-archive..?
    http://en.vedur.is/earthquakes-and-volcanism/earthquakes/tjornes-large/

    Would be nice with a new Island next to Iceland;)
    (I know, if wishes was horses)

  13. #14 Diane N CA
    July 26, 2010

    @Dennis #11 yeah, that one guy just doesn’t get it. And the pictures do speak for themselves.

    As for the recent quake activity, a lot of energy was released in a lot of areas. The Alutians have the Pacific plate diving under them and there was a lot of energy released there as well as the Phillipines. My guess is the energy release from the subduction in the Phillipines was more than the Alaskan quakes. The scale is logrithmic and each magnitude from 1 on up is 31 times stronger than the before it. In other words, a mag of 2 is 31 times stronger than a mag 1. I wouldn’t even want to try to guess at the TNT levels here. I bet someone here has a very good idea and could calculate it. That would be an interesting project. NOT one for me. LOL

  14. #15 Diane N CA
    July 26, 2010

    OT question: what is the spam thing that has been mentioned? Not that I want to see it, I just want to avoid it! Is it that little thingy at the bottom right of the page?

  15. #16 Carl
    July 26, 2010

    @Lurking et al:

    I just want to make yet another comment on the 60+ uplift largish pent-up energy-potential thingy that I otherwise answered in the former thread.

    Even if Iceland burst out in a 5400 cubik-kilometre lava eruption it would still be small compared to the Siberian Trap (1 million cubics) and Deccan Trap (0,5 megacubics).
    Nice with something that makes the coveted Yellowstone supervolcano look like a pile of flubber being eaten by a Graboid.

    http://en.wikipedia.org/wiki/Siberian_Traps (I know it is wiki, I am schnappsed up and lazy)

  16. #17 Passerby
    July 26, 2010

    The spam was removed.

    Tjornes Transform data
    GPS: The station at Árholt is located on the Tjörnes peninsula in North Iceland, between the Húsavík-Flatey transform zone and the Grímsey fracture zone.

    Data not available.

    Grimsey tremor plot
    hraun.vedur.is/ja/oroi/gri.gif

    Flatey tremor plot
    hraun.vedur.is/ja/oroi/fla.gif

    Others:
    Hedinshofdi tremor plot
    hraun.vedur.is/ja/oroi/hed.gif

    Brettingsstadir tremor plot
    hraun.vedur.is/ja/oroi/bre.gif

  17. #18 Dasnowskier
    July 26, 2010

    Turrialba may have some ash in it plume.

    http://www.ovsicori.una.ac.cr/videoturri.html

  18. #19 Dennis
    July 26, 2010

    okay i knew it was logarithmic calced but had forgotten how big that is :)
    Im exiting to see what will happen, we got some eruptions true, but all this noise for this ? sorry im not horny for something devastating just curious how nearly the whole earth is on rumble mode and its not only because we now have the tech to know whats going on around the world.
    The whole Tech is wonderful but it also make you think (http://www.ndbc.noaa.gov/station_page.php?station=55023).
    But thanks to this blog for some great answered about the deep quakes.

  19. #20 Passerby
    July 26, 2010

    The Siberian and Eimeran (China) flood basalts date to 250 MYA and the Deccan Traps to 60-68 MYA.

    The Columbia Flood Basalt group date contemporaneously with the Yellowstone hotspot and Afar Flood Basalt Event, 15-18 MYA. These date from near the end of the Antarctic Sheet interglacial period. The start of the most recent Antarctic Sheet reformation corresponds roughly to major climate cooling and drying, catalyzing the dessication of the Atacama, Saharan and Namib regions.

    Large igneous province formation is not random; most of it occurred long ago during major continental mass flux. rearrangements. Two spots, Iceland and Afar region, hold potential for minor flood eruptions.

    Doubtful there would be anything like a major basalt flood event in the near future.

  20. #21 mike don
    July 26, 2010

    Henrik: I think that the 600-foot ‘Heaven’s Mountain’ shows that the Danes have a finely-tuned sense of irony :o)

    Dasnowskier 18: Saw the dark plume for a minute or so, then darkness obscured everything. Is it the result of ash production: or just a pretty lousy weather system at the moment?

  21. #22 bruce stout
    July 26, 2010

    @Passerby, just finished the Rusov, Vaschenko et al paper which I had to read twice and am rather astounded by a couple of things. First the basic rigid coating soft substrate (RCSS) concept makes sense intuitively and places the focus on deeper convection currents in the asthenosphere. As I understand it, the lithosphere is merely along for the ride. That said, the whole hypothesis is based upon compressive deformation of a coupled lithosphere/upper mantle complex (i.e. slab) as it ploughs into the transition zone between upper mantle and lower mantle. If this is right, the observed pattern in the frequency of deep quakes at intervals of 50 km would be evidence that the transition zone must indeed mark a hard boundary forming one end of the deformation of the lithosphere with subduction at the surface marking the other, with the crumpling taking a sinusoidal shape determined by (if I understood correctly) the thickness and relative strength of the lithosphere.

    What really surprises me is the depth distribution charts they derived from NEIC data (Fig 5) with pronounced spikes at these 50 km intervals. That data looks too good to be true and I wonder why nobody ever commented on it before. If Lurking or any other whizz at plotting this stuff is perhaps interested I’d like to see if the USGS data corroborates this pattern. (y axis: frequency of deep quakes, x axis depth for the period 1973 to 2009 or similar).

    Definitely very interesting stuff!

  22. #23 Gordon
    July 26, 2010

    18 & 21 – I noticed that Turrialba plume has been well defined over the last few days. Currently obscured by cloud. Visibility is often poor, but I haven’t worked out if that is due to cloud as today, or to wind direction pushing plume towards webcam when there tends to be a darker colour of cloud.

  23. #24 Passerby
    July 26, 2010

    Bruce, the model is for bending stress modulus determination of a stiff laminate-softer body system (2 layers). You cannot disregard the soft layer. From the paper:

    >From Fig. 5 follows that this distribution has clearly
    defined periodical fine discrete structure with period L=50 km.

    That’s the minimal discrete structure within the deforming body.

    Sometimes it’s determined by the measurement method physics (lower boundary of physical measurement possible) and sometimes you see this type of repeating structural unit in datasets from boundary error / confidence interval estimates (central value +/- some #, the smallest interval that can be reliably assessed).

    Note also the smearing of EQ data near the floor of the lower mantle (550-700Km). I would guess that is a second major bending deformation of a semi-stiff body that still has some cohesiveness, entering into a looping circuit of purported large circulation patterns – a physical explanation. However, it may also reflect differences in material chemistry (melt temperature, crystalline properties) of various subducting crust/lithosphere combinations.

    We still see a tight clustering of Lurkings plotted EQ data centered about 600 klicks, which made me a very happy person because it fit the sensible/intuitive multilayer bending model.

    Very tidy approach to understanding deep focus earthquakes.

  24. #25 Dasnowskier
    July 26, 2010

    I think now the dark color of the plume was due to bad weather as stated by mike don.
    The glow in the predawn has been very strong at times leading me to think magma is still pushing to the surface. This could get interesting but is taking its own sweet time in human terms

  25. #26 Dasnowskier
    July 26, 2010

    P.S. A clear shot of the plume now shows it is very vigorous but doubtful that is is ash laden….at this time.
    http://www.ovsicori.una.ac.cr/videoturri.html

  26. #27 Lurking
    July 26, 2010

    @Dennis and all ‘yall.

    A question of power came up regarding the Moro Gulf quakes and the Alaskan quakes. Fortunately, I was able to grab the data before it evaporated to the ephemeral world of the archives…

    Eh… long day.

    Here ya go, Moro Gulf and Fox Islands quakes as discrete power plots… with a couple of notable nuclear explosions for comparison.

    http://i25.tinypic.com/2qiocxw.png

  27. #28 Passerby
    July 26, 2010

    Continuing our discussion of the Mechanism of Deep Focus EQs paper.

    L = cracking (stress-strain release) minimum length. For energy release equal to the earthquakes ranging from 3.9 to 5.3, L=50 and for all larger quakes > 5.4, L=100.

    Indeed, if we look at Figs 5 and 6, the fine shape of the curve describing the plotted EQs with depth (regardless of magnitude) has has fine structure that changes about every 100km, with a clear secondary structure emerging for smaller energy earthquakes at 50Km (those spikes).

    The characteristic folding length is 200km for both magnitude sets.

    The authors don’t say much about Fig 5, but I think we will.

    We’re very much interested to see when the L=50 signal spikes are prominent and when they are minimal in the curves for various time periods.

    What do you see for this set of graphs that stands out?

    Something is interesting about the time period after 1992 through 2002, a data period with a strong L=50 signal. The fine structure signal weakens from 2003-04 and diminishes in 2005-06, and is very low level in 2007-08.

    That means the L=100 predominates, we have much more energy in the deep focus earthquakes in the past few years.

    So now we will do a bit of razzle dazzle, for our paper’s authors, who must have missed this next article. Not only does this Nature article support our Russkie model and our plotted data of Philippine EQs (USGS dataset) with actual report of a slab discovered located at deep depth, the study results affords the same characteristic folded length, lambda, value of 200 km.

    The folded length of the slab is also equal to the depth of D Region, the bottom of the mantle, which is characterized by a change in crystalline phase change of the folded slab. (There is a world of science in that last sentence, too much detail to go into here.)

    This news brief and similar graphic in the Nature letter-article provide an excellent graphic of their finding, so you know what we are on about when we talk about characteristic folded length.

    The news brief describing the Nature paper:
    Giant Slab of Earth’s Crust Found Near Core.
    Live Science May 2006
    http://www.livescience.com/environment/060517_inside_earth.html

    LiveScience’s graphic for their news article
    http://www.livescience.com/php/multimedia/imagedisplay/img_display.php?pic=060517_fold_big_02.jpg

    The letter-article in the journal, Nature May 2006:

    Seismic detection of folded, subducted lithosphere at the core–mantle boundary. Nature 441z:333-336 (18 May 2006) doi:10.1038/nature04757

    http://www.nature.com/nature/journal/v441/n7091/full/nature04757.html

    The paper’s graphic of the folded ‘taffy’ slab.
    Fig 4. A cold buckled subducted slab (blue) in the lowermost mantle may account for the thermal structure that results in a step in the perovskite/post-perovskite phase transition.
    http://www.nature.com/nature/journal/v441/n7091/fig_tab/nature04757_F4.html

    *satisfied sigh*

  28. #29 Passerby
    July 26, 2010

    Necessary explanatory graphics of the earths interior, for the D” layer at the deep mantle-core interface:

    en.wikipedia.org/wiki/Mantle_(geology)
    en.wikipedia.org/wiki/Core–mantle_boundary

  29. #30 gina ct
    July 26, 2010

    eyjaf is sending a modest plume skyward and it appears as if there is a reflected red glow in it
    this could well be a anomaly in the cams reaction to the low light or—

  30. #31 Lurking... in the bush behind you
    July 26, 2010

    Those last two links… are the levels authoritative?

    If so I may incorporate those levels in a quake plot or two.

  31. #32 Renato Rio
    July 27, 2010

    #30 @Yes, Lady E is showing a vigorous steam plume. But I don’t see the red glow you mentioned. Couldn’t it be a sunrise light trick?
    @passerby #28 I think Bruce stout has grasped much on those articles. I’m a slow pupil. Still have to do a lot of my homework. But just keep posting. Cool stuff, indeed.

  32. #33 Carl in a Thunderstorm
    July 27, 2010

    @passserby (and lurking):

    Nice work with the deep quakes folding slab theory! I really think you are on to something. Would be nice with a good provable/refutable prediction hooked onto it. Keap it up!

    Just wanted to point out also that I in no way think we will have an event like the Siberian Trap in the near geological future. I just wanted to point out to lurking that Iceland isn’t that big on a bigger scale. Sometimes I even wonder if we ever again will due to that the energy has dropped in the system (eg. earth). Even the likelihood of a 5000+ Icelandic flood basalt is rather unlikely I think.

  33. #34 leon
    July 27, 2010

    hi all http://www.time/health/article10,8599,2006195,00.html Deep underground, miles of hidden wildfires rage hope you find this link is intresting..

  34. #35 leon
    July 27, 2010

    hi all,,again the page appears to be broken that no problem still click on it and scroll down the page and click on to 3 your looking for Time magazine US Edition August 2010 vol 176 no5 click Health and there’s the story on the above link @34

  35. #36 Jane
    July 27, 2010

    @34, leon, this link works: http://www.time.com/time/health/article/0,8599,2006195,00.html That’s bad news, “more than 100 fires are burning beneath nine states.” Worse: “But geologists say many fires go unreported, driving the actual number of them closer to 200 across 21 states. Most have burned for years, if not decades.” Not only are the fires burning up coal reserves uselessly, but they’re polluting. A question for geologists: is there no way to put out the fires (or remove the coal)?

  36. #37 Lurking
    July 27, 2010

    @Jane

    If you open up the seam so that you can get at it…. you introduce Oxygen.

    Fire = Fuel + Oxygen + Heat

    More recently that triangle has been updated to include “chain reaction” but the triangle will work for our purposes.

    Dumping copious amounts of water will yield CO and other combustible gases… plus you may get a geyser effect, or possibly a small steam explosion.

    Either way, you get a liability issue if property or residents in the place that it comes out are harmed or injured.

    You can also find another feature at Derweze (the gate) in Turkmenistan.

    “While drilling in 1971 geologists accidentally found an underground cavern filled with natural gas. The ground beneath the drilling rig collapsed, leaving a large hole with a diameter of about 70 meters at 40°15′10″N 58°26′22″E (The Door to Hell). To avoid poisonous gas discharge, it was decided to burn the gas.”

    It’s ahh… still burning.

    http://en.wikipedia.org/wiki/Door_to_hell#The_.22Door_to_Hell.22

  37. #38 Passerby
    July 27, 2010

    This is a topic I’ve been following for most of the past decade.

    Wiki page has a reasonably complete intro to the subject:
    en.wikipedia.org/wiki/Coal_seam_fire

    Recent 2010 article on the long burning Centralia PA coal fire and discussion on a new approach, employing technology developed for fighting forest fires with injectable foams:

    http://www.earthmagazine.org/earth/article/33d-7da-5-5

    Anupma Prakash’s website at the Univ Alaska:
    http://www.gi.alaska.edu/~prakash/coalfires/coalfires.html

    Some of her links are out of date.

  38. #39 Lurking
    July 27, 2010

    Sort of a diversion… and something to mull over.

    I have long read that the Little Ice Age was the little ice age in part, because of the much increased volcanic activity of the time. I’ve pretty much accepted that… and saw it as an augmentation of the Maunder and Dalton minimums of the time. Never really had a way to find out one way or the other.

    I ran across the Large Holocene Eruption list over at http://www.volcano.si.edu a few weeks ago, and grumbled at how hard it was to make use of the data other than looking at the columns and reading about the events.

    What I have done, is to force the data into a usable form. REMEMBER, that a lot of the volcanic data is from various sources and have date accuracies of up to hundreds of years… the intensity of the eruptions is also prone to wide inaccuracies…and to make it worse, where there was just a Plinian or Caldera forming event noted, it didn’t make it into the plot. The VEI info was averaged across 21 events with a central moving point average. This is what I plotted.

    Civilization data was picked off of entries in Wikipedia, so take that with a grain of salt. These were place on the plot just to get a frame of reference for what was going on in the world while the average world wide volcanic intensity was at that level.

    Enjoy.

    http://i32.tinypic.com/f44i8x.png

  39. #40 Jane
    July 27, 2010

    @Lurking and Passerby, thanks for the links.
    These photos show why Darvaza is called The Mouth of Hell. http://johnhbradley.com/pictures2.asp?var=070707darvaza
    A coal seam fire in Germany has been burning for more than 400 years, since 1668!

  40. #41 bruce stout
    July 27, 2010

    @ Lurking. jaw just dropped. off to kitchen to get salt… what an amazing plot!!

    Do you think the downwards slope might be due to a greater number of VEI 4 eruptions getting recorded in the last 1000 years or so when people were around to record them?
    Other than that, do you have any ideas why the plot exhibits such a pronounced wave form?

  41. #42 Renato Rio
    July 27, 2010

    @Lurking: Interesting plot indeed. Thanks once more.

  42. #43 Renato Rio
    July 27, 2010

    BTW: Have you people noticed that Lady E has been exhibiting an unceasing, robust steam plume these days?
    I love this volcano.

  43. #44 Passerby
    July 28, 2010

    Ho-hum. Three years ago, I plotted the entire GVP catalog. Binned the eruptions by VEI. A rather interesting pattern emerges.

    What was your point in adding the Middle Eastern and Western civilizations. Leaving out Asia removes….interesting perspective of cause and effect.

    No, the volcanoes didn’t was not responsible for causing the LIA or the Medieval Warming that proceeded it. But glacial rebound had a hand in pushing eruption probability in both the northern and southern hemispheres. Larger drivers were at work: large, multi-decade to centuries of climate instability by large solar fluctuations with feedback loops in the oceans and large climate ensemble cycles. These were aided and abetted by major volcanic eruptions.

    Makers and breakers of empires. Plot human population on your graph.

  44. #45 Lurking
    July 28, 2010

    @Passerby,

    “What was your point in adding the Middle Eastern and Western civilizations. Leaving out Asia removes.”

    Mainly ethnocentrism. There was a significant dynasty change (Xia Dynasty) shortly after Thera… probably associated with that whole “mandate of heaven” thing and a slight conflict with the rising Shang Dynasty.

    I concur with the LIA not being in that cause and effect chain, but it didn’t help. Mainly I did to plot in order to be able to throw the B/S flag at what I have heard.

    Your GVP catalog binning sounds like a really interesting data snag. Is that info online? It sounds like it would have higher resolution than mine.

    @bruce stout

    “Do you think the downwards slope might be due to a greater number of VEI 4 eruptions getting recorded in the last 1000 years or so when people were around to record them?”

    Yes. I strongly believe that. Remember that the older the data is, the more that it’s a matter of a geologist out in the field puzzling over the landscape.

  45. #46 Lurking
    July 28, 2010

    Okay… same plot, added global population estimates (from http://www.census.gov) made it less ethnocentric by adding a few Chinese Dynasties and a rough track of Sumeria / Babylonia.

    (Note: Babylon didn’t get taken over by Rome, the line just ran into Rome. At the time, the Etruscans were running the show in Rome. The Persians are the ones who took over Babylonia at about this time)

    Other than that it’s pretty much the same plot.

    http://i26.tinypic.com/ru9mk1.png

  46. #47 Stefan
    July 28, 2010

    Good Morning everyone

    It’s a nice day in southern iceland and you can see a wonderfull steamplume rising up from Eyjafjallajökull. Looks quite amazing that even after the eruption is over for some time, there is still this steamplume

  47. #48 Lurking
    July 28, 2010

    In order to keep anyone from getting the impression that volcanic activity is much much lower than in the past, here is a plot of the raw data from my last plot. Take note of the increase in sample, and that the relative number of large events isn’t that different over time. I’m pretty sure that as the population went up, the number of eruptions that were noticed went up also.

    http://i32.tinypic.com/30upwqp.png

  48. #49 bruce stout
    July 28, 2010

    .. on this correlation between volcanic activity and population (I think I have mentioned this before) but there have been pretty advanced civilizations living in the Bismarck archipelago since the Lapita cultural complex arrived at about 1600BC. This region is where an awful lot of these VEI 4 or higher eruptions have taken place. This makes me kind of optimistic that humankind is pretty adept at adjusting to the impact of large eruptions.

  49. #50 Lurking
    July 28, 2010

    That’s why we have legs.

    “…run Forrest!! Run!!”

    As primates go… I think we may have a speed/distance advantage.

  50. #51 JulesP
    July 28, 2010

    OT – As a follow up to a previous discussion several months ago, and for those who may be interested. Spacequakes have been discovered, and could potentially contribute to the total energetics of the earth, in however small a manner; there is a lot that is unknown. See http://science.nasa.gov/science-news/science-at-nasa/2010/27jul_spacequakes/

  51. #52 bruce stout
    July 28, 2010

    @ 50 :lol: Head for the hills!!!
    (think) No wait, don’t head for the hills!!!

  52. #53 Renato Rio
    July 28, 2010

    #50 #51 You guys don’t have to worry about quakes. I’m more concerned about the development of Korea crisis and increase of international economical failure that might lead to a period of anarchy/dictatorships. We’re back to pre-Holocene times in human History. :(
    @Lurking: your plots are great!

  53. #54 Lurking
    July 28, 2010

    @Renato Rio [53]

    Well, it’s supposed to get worrisome for the US Admin in August, and things are supposed to get really Nasty in Nov. That is, if you follow the alternative fringe. Dunno what, dunno how.

    As an antithetical Frank Boman from 2001 Space Odyssey would say “Something Horrible”

  54. #55 Carl on Economics
    July 28, 2010

    @53 & 54:

    I guess they are refering to two large loans that will be out-standing during the fall without any chance of the US being able to pay them.
    Well, it is not any big news that the US cannot pay it’s debts any longer, the US haven’t paid mortgages and in many cases interests for quite some time now. Problem is that nobody will give any extensions anylonger, or for that matter, give new credits. So it is time to actually try to get the economy to get into ballance, but the likelyhood of that is slim to say the least.
    But it is not as large a problem for the world economy any longer since the US ecnomy is falling in importance. Pretty much the EU together with China and India have taken up the slack by now. But it might not be that fun for those here that are americans…

  55. #56 Kultsi, Askola, FI
    July 28, 2010

    Heh. The Múlakot pic shows a plane in the bushes.

  56. #57 Passerby
    July 28, 2010

    @56: they moved it out of the way to cut the lawn.

  57. #58 Lurking, over there.
    July 28, 2010

    @Carl on Economics

    “…Pretty much the EU together with China…”

    Ummm yeah. Ever check out that PIIGS acronym?

    China refuses to pony up and let it’s currency float so good luck with that one. My guess we are sitting at a precipice staring strait down at the bottom of Kondratiev cycle 5. Perpetually over extended and bloated to keep the money flowing… never letting the natural economic flow and contractions occur.

    So… here we are, hovering right over the pit bottom of where the depression/contraction phase would have started it’s upward turn…. but we never traveled gently down that path. The only way to get there now is a near vertical drop.

    Yee Haw…

  58. #59 Lurking
    July 28, 2010

    Okay… 3rd version.

    Passerby and bruce stout’s comments prompted me to rethink that average global VEI number. With the increase in population and expansion of civilization, more eruptions would be noted and recorded. This is evident in the number of events in the rawplot in post [48].

    I went back and binned the data at 100 year intervals, summing the VEI and dividing by the number of events. This yields an overall average VEI by century. There is still room for error, but it’s gonna be less glaring than the previous versions of this plot.

    http://i28.tinypic.com/15ejoyp.png

  59. #60 Passerby
    July 28, 2010

    That’s closer to reality. You can double check it by superimposing a transparency copy of the raw data over the last graphic.

  60. #61 josefina peñaloza perez
    July 29, 2010

    dr. erik klemetti.
    your blog looks very interesting to us, we are college students chile, you give information from our mountains of the Andes is extremely important and a great pleasure for us.
    the information provided in this article you realize their great work and research in relation to volcanology.
    Finally we put the following question, Dr klemetti, compared with last earthquake occurred on 27 February in our country, will it have any implications the volcanic activity of the Andes with the seismic activity?
    was a pleasure to leave this message, wait for your answer
    good bye

    Josefina Peñaloza and Andres Rojas
    science student teachers Universidad Catolica del Maule, Talca, Chile.

  61. #62 Renato Rio
    July 29, 2010

    #61 Buenas tardes de Rio a los hermanos en Chile!
    @Josefina and Andres: there was much speculation here and in other related blogs over the subject “quakes and volcanic implications” when February EQ occurred in Chile. Right now, in another thread, a similar discussion is taking place on correlations between tectonism and volcanism in the Pacific microplates, maybe it would be interesting if you take a look there, although mechanisms involving Nazca plate subducting under S. America are far easier explained.
    We have the example of Puyehue-Cordon Caulle back in the 60s that erupted just after the big Chilean EQ, as well as other volcanoes. So I think (but I’m no expert) that there may be a “help” from an earthquake, if the volcanoes are close to an eruption. But this is still a very debatable matter.
    You came to the right place: Dr. Klementii has worked in Chile and is very well acquainted to Chilean volcanism.
    I must confess, that, in a way, Chilean volcanoes are “my” volcanoes, since in Brazil we have none, so the subject is of most interest to me (I saw Villarica erupting back in 72). Saludos!

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