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Questions about calderas

  1. Aug 17, 2008 #1
    I have a few questions about calderas, specifically, the Yellowstone and Long Valley Calderas.

    I read in this article that the Yellowstone Caldera could be dying, but may have enough juice left for one "catastrophic" eruption. What would the nature of that eruption be?

    Also, what are the odds of either the Long Valley or Yellowstone Calderas causing a catastrophic eruption in our lifetimes (say, the next 100 years)? I've heard that the Yellowstone one is on a 600,000 year cycle and its last eruption was 650,000 years ago. So does that mean we can expect another catastrophe from it soon?

    Is there any way for us to forecast when these supereruptions will come?
     
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  3. Aug 19, 2008 #2

    Mk

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    Re: Calderas

    I'm pretty sure "caldera" is the physical shape left after a huge volcano eruption—the volcano is not a caldera. The caldera is the mark it made, like a crater after a meteor.
     
  4. Aug 19, 2008 #3
    Re: Calderas

    I think that if an eruption is immanent, we will see signs. It is unclear how extreme the signs need be before we conclude it will erupt. The problem is that yellowstone is active, and is always showing signs of activity some of which are in short cycles, smaller eruptions happen too, so even if we know something is going to happen, we don't know if it is just a hickup or if it will be the real thing. Another problem is that we have never observed a super volcano erupt so we don't know what the signs will be exactly. It is possible that the extreme signs will happen only moments before total destruction, then again maybe it will be slow and will swell up like a bee sting before it goes. It is tough because it would be an economic disaster to evacuate half the nation and then nothing big happens.
     
    Last edited: Aug 19, 2008
  5. Aug 20, 2008 #4
    Re: Calderas

    Everything about Caldera forming volcanism here:

    http://www.elsevier.com/wps/find/bookdescription.cws_home/714660/description#description

    It is believed that such an eruption would be announced by an uplift of the surface due to the increasing magna mass below.

    http://pubs.usgs.gov/fs/2005/3024/fs2005-3024.pdf

    Sometimes it is speculated that the Yellowstone volcano is overdue after 640,000 years of dormancy, however seeing eruptions 2.1 million years ago 13.0 million years ago and 0.64 million years ago it could easily be another 100,000 years and it still being in the "regular" cycle, there is simply nothing to predict here.
     
  6. Aug 29, 2008 #5
    Re: Calderas

    I've read that the magma in the caldera is, at some places, as little as 5 meters below the surface. If one were to access that magma with a drill or explosive, so as to relieve the pressure, could that lead to an eruption?
     
  7. Aug 29, 2008 #6

    wolram

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    Re: Calderas

    I read some where that if the (roof) of a caldera collapsed it could trigger an eruption,
    not saying the whole area of the caldera, just a significant portion.
     
  8. Aug 29, 2008 #7

    matthyaouw

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    Re: Calderas

    I think 5 may have been a misprint. I doubt very very much that it's an accurate figure.
    No one has ever tried to drill in to an active magma chamber before. I can't really speculate too much on whether it would be possible or what the effect would be.
    Think of the legal (and moral) problems surrounding it though. We currently have no indications that the volcano will undergo a major eruption within any of our lifetimes. What if we drilled in to it and it blankets a whole state in ash, destroys homes and displaces people as a result? Every one of those people could argue that as an eruption wasn't forecast, it is the drillers fault they lost their homes, property, crops etc. Each one of them would need to be reimbursed and compensated. Things are tricky enough with cases related to cloud seeding causing damaging hailstorms, or the Sidoarjo Mudflow Which are relatively small compared to the effects of an eruption
     
  9. Sep 3, 2008 #8

    gdp

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    Re: Calderas

    More like 500 meters, not 5 meters.
     
  10. Sep 3, 2008 #9

    gdp

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    Re: Calderas

    Exactly. About all one can say from these data is that it's likely that Yellowstone may erupt sometime, but the alleged "cycle" of "about 600,000 to 800,000 years" is only an "order of magnitude" estimate.

    One cannot say much more from these data, other than based on the past three data points, it is probably unlikely that Yellowstone would have erupted any sooner than ~70,000 years after the last eruption, and it's also probably unlikely that it will wait as long as ~7,000,000 years until the next eruption (unless of course the mantle plume feeding it has died...). That's about as close to "zero predictive power" as one can get while saying anything at all... :/
     
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