Eruptions

A bit of news for your last Monday in September:

i-e96867ecaf857e9a90c2d0f9681d8884-LaacherSee.jpg

Pumice deposits from the ~13,000 year old Laacher See eruption. Image by Erik Klemetti, taken in August 2007.

  • More press for Dr. Joyce and his campaign to make the people of Australia terrified that volcanoes will destroy them. He warns of “new volcanoes” springing up in the Ballarat region to the northwest of Melbourne (which, incidentally, is where I pointed out might be the most likely place for future volcanism). Yes, sure, we should expect that a new, unknown scoria cone may form in the Newer Volcanic Province – I mean, that is what happens in these fields, you get volcanoes like Paricutin that start erupting where there was no volcano. However, trying to mitigate against such a thing, well, it might be like trying to build defense against an asteroid by randomly placing it on the surface of the planet somewhere. OK, maybe the odds aren’t that astronomical, but as the earthquakes in Saudi Arabia earlier this year show, trying to determine when/where a new scoria cone might spring is really, really tough.
  • Speaking of tough, there is a little piece about how all the ash and tephra from the Laacher See volcanic eruption in Germany ~13,000 years ago did a number on the teeth of humans and animals in Europe. For those of you unaware of this volcano, the Laacher See is a caldera smack-dab in the middle of the western Germany and it produced a significant eruption that not only covered the region in ash and pumice (see the deposits in the picture above), but spread ash up into Scandinavia. And who says that Europe lacks (potentially) devastating volcanoes (well, other than Italy and Greece)?
  • Mt. Baker in Washington (state) has gotten some new monitoring equipment installed on its slopes. A new broadband seismometer was installed near the highest ski patrol lodge and it is one of the new seismic stations located on the main edifice of a Cascade volcano (surprising, eh?)

Comments

  1. #1 Boris Behncke
    September 28, 2009

    Sad thing the reports on the quite interesting correlation between the Laacher See (Germany) eruption and tephra damage to teeth has once more been vested in a “supervolcano” context … the term “supervolcano” itself is misleading, because it literally means “more than a volcano”, which no volcano is; the same is true for “supereruption”. But the Laacher See eruption, as significant as it was, was a far cry from what is usually called a “supereruption”, such as Toba’s or Yellowstone’s major events. The Laacher See eruption very strongly mirrors that of Vesuvius in AD 79, expelling about 5 cubic kilometers of tephra, some of that as pyroclastic flows, and the same eruption today would wreak havoc to the center of Germany. But those eruptions sometimes called “supereruptions” rather produce magma volumes of hundreds or thousands of cubic kilometers, so we’ve got a difference here by two or three orders of magnitude.
    Nobody calls Pinatubo a “supervolcano”, but its eruption in 1991 was slightly more voluminous than Laacher See’s eruption about 13,000 years ago.

  2. #2 Fitz
    September 28, 2009

    How about calling them Ubervolcanoes?
    (how do you put umlauts on the U with this keyboard?)
    Its scientifically just as accurate and has the benefit of making the Germans seem responsible in some way.
    I’m keeping a list of all the calderas I run across. Its getting long, especially including the “small” calderas that sit inside the large ones.
    I’m sure someone has a complete list already, I just cant find it on the net.

  3. #3 Fitz
    September 28, 2009

    PS Im curious concerning the layering in that photo?
    I see 6 layers, I assume the thick top one (layer 1 – brown w gray bands) is from 13,000 years ago?
    Then in order going deeper-
    Layer 2 – plain brown
    Layer 3 – light gray with abundant weed growth
    Layer 4 – plain brown
    Layer 5 – light gray without weeds
    Layer 6 – the one you’re standing on, brown, similar to 1, and looks very thick.
    Questions: are all the layers volcanic?
    Did anyone date them? Can we assume they are all 13,000 yrs apart?
    What is different in Layer 3 that the plants like so much better than the other layers?

  4. #4 Boris Behncke
    September 28, 2009

    To Fitz: the ENTIRE set of layers is of that one eruption. This is an outcrop very close to the volcano, so here the deposit is quite thick – but also quite complex as you have noted. The thick light-colored, fine-grained layer at about the same level as the persons is of a pyroclastic flow, the set of thinner layers below (mostly visible behind the persons) is mostly surges produced by the initial vent-clearing, hydromagmatic activity.
    Above the thick pyroclastic flow deposit we have one gray layer, which is Plinian pumice fall, followed upward by a series of thin surge/pyroclastic flow layers (with some weeds), and on top of that there is the so-called “Autobahn” (two coarse-grained, gray pumice fall deposits separated by a thin surge deposit, if you look carefully). Then the succession takes on a slightly darker gray hue, which is due to a compositional change in the emitted magma (same as observed in the Vesuvius AD 79 deposit), as a slightly more mafic portion of the magma reservoir was tapped. All the upper layers are an alternation of surge/small pyroclastic flow and fall deposits, pointing to the intermittent character of the activity in the later phases of the eruption, with hydrothermal fluids repeatedly entering into the conduit.
    I must correct my volume information in the previous comment; the Laacher See eruption expelled 6 cubic kilometers of magma and therefore was slighly larger than the 1991 Pinatubo eruption – still a minuscule burp compared to a “super eruption”. Nothing like an Übervolcano.

  5. #5 bruce stout
    September 28, 2009

    I wanted to make a reference back to Schmincke’s book “Volcanism” (to get back to that discussion we had a few weeks ago) but I see Boris has beaten me to it.

    The other thing about the Eifel is that it is an expression of an emerging rift zone that extends from the North Sea down through the Rhine valley to the Massif Central (or so I understood it.. please correct me anyone if I am wrong!!)

    We also have a few volcanic cones in our neighborhood (near Stuttgart) that look a little bit out of place, but there they are! Who knows, maybe SE Australia is next!

  6. #6 Fitz
    September 28, 2009

    THANK YOU Boris! Well done.
    Has anyone tried to estimate the duration of the eruption by looking for seasonal inclusions between the layers like pollen etc? If it all erupted in a week you wouldnt find any differences but if it went off over the space of a few months you might.
    Im going to speculate that the lt grey layer with weeds holds moisture better than the others due to the grain size?

  7. #7 Gijs
    September 28, 2009

    The volcanic features (diatremes) near Stuttgart (‘Uracher Vulkangebiet’ or ‘Schwäbischer Vulkan’) are ‘much’ older than the quaternary volcanic cones of the Eifel.

    http://de.wikipedia.org/wiki/Schw%C3%A4bischer_Vulkan

    Anyway: back to Laacher See, my favourite volcano. The Eifel is the volcanic area that is closest to where I live (Southern part of the Netherlands), so I go there pretty often. Coming weekend is when I go rock collecting there again. I always visit Laacher See when I go there, because of the impressive looks of the volcano and the very interesting minerals that can be found in it’s deposits (like Haüyn).

    The entire Eifel region is very suitable for educational purposes, and my students always find it very interesting to know that volcanoes can be found in their own ‘backyard’. Especially when they learn what the effects of eruptions like the Laacher See eruption could have on Western Europe, which is ofcourse relevant to them.

    @ Fitz: close to the Laacher See caldera are two more small calderas: the ‘Wehrer Kessel’ (215.000 years BP) and the ‘Rieden volcano’ (between 360.000 and 430.000 years BP).

    Relating to the reports on what’s going on in Australia: in Germany there have been comparable speculations concerning the Eifel volcanism. More people are becoming aware of the fact that the area is likely to have new eruptions in the future, and seen the fact that almost all of the volcanoes in the Eifel are monogenetic, an eruption from a new volcano would be likely. Although I hope to see an eruption in the Eifel region in my lifetime, there are, like in Australia, no signs of impending danger, and ofcourse a small and ‘harmless’ eruption would do. No need for another event like the Laacher See eruption in my (economical) backyard, and in the backyards of so many others living close(-r) to the volcano.

  8. #8 Gijs
    September 28, 2009

    @ Fitz (didn’t read you most recent comment before I posted mine): if I’m not mistaking, most of the activity took place within more or less a week time (although it’s difficult to say how much time it took before the phases of declining activity were over), with the Plinian phases lasting for about 7 to 11 hours. I believe I read somewhere that it happened somewhere during late spring (may or june), but I don’t have the source of that information anymore I’m afraid.

  9. #9 Gijs
    September 28, 2009

    Correction (yes, I also noticed the typo and spelling mistake) of something I stated in my previous comment: the eruption occurred somewhere near the end of July.

  10. #10 Les Francis
    September 29, 2009

    A few weeks ago there was a press release that made the point that there is between 650 – 950 million ounces of recoverable gold at a depth of between 30 – 100 metres below the surface in the triangle area of Ballarat, Castlemaine and the outer skirts of Melbourne.
    Lets hope we get to it before the volcanic eruption :)

  11. #11 mike don
    September 29, 2009

    There’s probably not much that Eifel and Ballarat have in common..I’d guess that on the evidence Ballarat would produce a basalt scoria cone and accompanying lava flow rather than a major Plinian event. Possibly a Paricutin-size eruption, more likely something similar in style and appearance to Heimaey 1973. But if you are worried about basaltic volcanic fields, what about the Auckland Field? Still live (last eruption about 700 years ago, if I recall the details right) and the uncomfortable possibility that a new cone could pop up in downtown Auckland

  12. #12 Gijs
    September 29, 2009

    Of the ± 350 quaternary Eifel volcanoes, there are around 70 maars, three small calderas, and around 15 tuff rings. The rest of the volcanoes are small to medium sized scoria cones, tuff cones and scoria rings and there are some small phonolitic lava domes too. Pretty much comparable to most volcanic fields around the world. If you look at statistics (worth almost nothing in volcanology, especially when there are no clues whatsoever on if and when a new eruption will occur) the likelyhood of a relatively harmless basaltic eruption happening in the future in the Eifel is greater than of a great Plinian eruption happening there.

    But I have to say that I would rather like to have some real estate in the Eifel than in Auckland. One of those places in the world where you just don’t want to build your house I think. Although Naples is probably even worse…

  13. #13 bruce stout
    September 30, 2009

    Hey Auckland is ok! Great beaches. It’s also where my family live and still the place I call ‘home’, though I now live near Stuttgart. Personally I’d prefer living close to a volcanic risk than an earthquake risk which strikes with no warning at all.
    That said, my cousin lives near Okataina and his wife is seriously worried so about a major eruption so I tried to relativize the risk for her. I’m afraid I failed miserably!!

    On the risks stakes, I doubt that Auckland is that high up there, especially compared to any of the decade volcanoes.

  14. #14 Gijs
    October 1, 2009

    ‘Unexpected’ earthquakes… you mean the Albstadt shear zone combined with the Hohenzollerngraben? I see your point ;-) .

    I still wouldn’t want to live in Auckland from a geological point of view. But I guess it’s easier for me to say that, because I don’t call that place ‘home’. I live in an area that is close enough to the Roermond – Aachen – Düren – Köln earthquake area to get damage from a potentially big earthquake that could happen there, but somehow it doesn’t make enough difference (yet) to leave.

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