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Old 06-17-2009, 01:50 PM
 
Location: Universal City, Texas
3,109 posts, read 9,704,161 times
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IS A supervolcano brewing beneath Mount St Helens? Peering under the volcano has revealed what may be an extraordinarily large zone of semi-molten rock, which would be capable of feeding a giant eruption.
Magma can be detected with a technique called magnetotellurics, which builds up a picture of what lies underground by measuring fluctuations in electric and magnetic fields at the surface. The fields fluctuate in response to electric currents travelling below the surface, induced by lightning storms and other phenomena. The currents are stronger when magma is present, since it is a better conductor than solid rock.

Supervolcano may be brewing beneath Mount St Helens - environment - 10 June 2009 - New Scientist


I've got a question to pose. I'm an old ex geology major from the 1960's.
Illrelevant I suppose, but I've been thinking. Recently, scientist have discovered an even larger magma chamber beneath Yellowstone, and now they are finding a large magma chamber beneath Mt. St. Helen's. Hawaii is a hot spot and there are some hot spots in Asia. Wouldn't it be interesting if they discover that there are these large magma chambers beneath many or most of the large volcanoes around the world?

And what if many of the dormant, extinct volcanoes have magma chambers beneath them? Austin, TX has a dormant volcano (Pilot Knob) on the southeast side of town. It lay at the bottom of the ocean when Austin was under water during Creteaceous.

Just some weird thoughts.
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Old 06-23-2009, 03:45 PM
 
Location: Southern Arizona
921 posts, read 1,401,026 times
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Came upon this web site. Could be very interesting if you happen to be watching at the right moment

Volcanocamera.com - LIVE - Mt. St. Helens and Mount Rainier Webcam - volcano camera
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Old 06-24-2009, 12:00 AM
 
Location: Rural Northern California
1,020 posts, read 2,723,828 times
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Quote:
Originally Posted by gy2020 View Post
I've got a question to pose. I'm an old ex geology major from the 1960's.
Illrelevant I suppose, but I've been thinking. Recently, scientist have discovered an even larger magma chamber beneath Yellowstone, and now they are finding a large magma chamber beneath Mt. St. Helen's. Hawaii is a hot spot and there are some hot spots in Asia. Wouldn't it be interesting if they discover that there are these large magma chambers beneath many or most of the large volcanoes around the world?

And what if many of the dormant, extinct volcanoes have magma chambers beneath them? Austin, TX has a dormant volcano (Pilot Knob) on the southeast side of town. It lay at the bottom of the ocean when Austin was under water during Creteaceous.

Just some weird thoughts.
Interesting article! I'd have to say though, if massive magma chambers were found under most large volcanoes that would more likely indicate that it takes more than a massive magma chamber to produce a super-large eruption (on the scale of a VEI 7 or 8 event). Basically, we know from studying ash fall patterns and from the historical record that super massive eruptions are very rare. No matter what new science we discover, global interval between such catastrophic events is quite large. Also, to your point about Hawaii, consider that the Hawaiian Island volcanoes are less violent shield volcanoes (because their magmas are highly mafic, and thus contain less dissolved gasses than their felsic counterparts).

Extinct volcanoes can potentially still sit atop partially molten magma chambers, because liquid rock takes a very, very long time to cool, and this can often cause hot springs and/or geysers to exist in the area, but is not necessarily indicative that an eruption is likely or possible. Yellowstone is a unique beast. It is most commonly thought that the caldera sits above an active hot spot in the Earth's mantle, which would explain the chain of extinct calderas that exist to the South West (which became extinct as the motion of the North American plate moved them off of the hot spot). There are other super-volcanoes to worry about in North America however, Long Valley Caldera in Eastern California for example, but the eruption interval for these sorts of events is very large.
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