St. Helens part of a Super-Volcano?

[jimmy olsen]

Oh noes, Camper's doomed!

http://www.nzherald.co.nz/nz/news/article.cfm?c_id=1&objectid=10578436

National RSS Email Print
Alarm bells ring over volcano find
New 4:00AM Monday Jun 15, 2009

A New Zealand geologist has triggered concerns about the possibility of another American "supervolcano" building under Mt St Helens.

GNS scientist Graham Hill has found big, connected channels of semi-molten rock beneath the southern Washington state mountain, which killed 57 people when it erupted in 1980, New Scientist magazine reports.

The discovery has revealed what may be an extraordinarily large zone of semi-molten rock, which would be capable of feeding a giant eruption.

The New Zealander led a team that set up sensors around Mt St Helens and found a column of conductive material that extends downwards from the volcano.

About 15km below the surface, the relatively narrow column appears to connect to a huge zone of conductive material.

This larger zone was first identified in the 1980s by another survey, and was found to extend all the way to beneath Mt Rainier 70km to the northeast, and Mt Adams 50km to the east.

It was thought to be a zone of wet sediment, water being a good electrical conductor.

But because the new measurements showed an apparent conduit connecting this conductive zone to Mt St Helens, Dr Hill now thought the conductive material was more likely to be a semi-molten mixture.

Its conductivity was not high enough for it to be pure magma, so it was more likely to be a mixture of solid and molten rock, he said.

But Oregon State University expert Gary Egbert, who was not a member of the research team, told the Oregon Public Broadcasting Service that he would be more cautious.

"It seems likely that there's some partial melt down there," given that it is a volcanic area, he says.

"But part of the conductivity is probably just water."

If the structure beneath the three volcanoes is a vast bubble of partially molten rock, it would be comparable in size to the biggest magma chambers ever discovered, such as the one below Yellowstone National Park.

Every few hundred thousand years, such chambers can erupt as so-called supervolcanoes - the one below Yellowstone did about 640,000 yearsago.

These enormous eruptions can spew enough sunlight-blocking ash into the atmosphere to cool the global climate by several degrees celsius.

Asked whether Mt St Helens could erupt like this, Dr Hill said: "A really big, big eruption is possible if it is one of those big systems like Yellowstone.

"I don't think it will be tomorrow, but I couldn't try to predict when it would happen."

He said further measurements probing the structure of the crust beneath the other volcanoes in the area could help to determine if the zone connects to them all.

- NZPA

[sbr]

Doomed.

[Palisadoes]

Uh-oh!

[sbr]

Uh-oh!

At least there is an ocean between you as this shit; I have St Helens an hour to my north and Yellowstone close enough to kill me when it goes. 

[Darth Wagtaros]

Uh-oh!

Spaghettios!

[Grey Fox]

What would Jesus do?

[Ed Anger]

What would Jesus do?

Keep standing outside Home Depot, like he does every day.

[Grey Fox]

Business as usual then.

[Palisadoes]

Uh-oh!

At least there is an ocean between you as this shit; I have St Helens an hour to my north and Yellowstone close enough to kill me when it goes.

I think you should look into relocating sometime soon haha! Pretty bad location you've got at the moment, considering.

[Neil]

I am unworried.

[KRonn]

Scary stuff! But then, we do know that a super-volcano eruption is possible sometime, somewhere, right? There was one in the 1800s in Indonesia, I think it was called Krakatoa. Caused there to be kind of no summer across some areas, such as the northern US that year.

[alfred russel]

Scary stuff! But then, we do know that a super-volcano eruption is possible sometime, somewhere, right? There was one in the 1800s in Indonesia, I think it was called Krakatoa. Caused there to be kind of no summer across some areas, such as the northern US that year.

I think Krakatoa was just a big volcano. A supervolcano is on a much more massive scale--and might have effects something akin to a nuclear winter. I think there might have been a supervolcano at some point in prehistory that almost caused humans to go extinct. Or maybe that was just a big volcano too.

[Ed Anger]

Business as usual then.

Meanwhile, disaster documentary makers creamed their pants.

[PDH]

Why the fuck can't there be a mini-volcano under Tim?

[Neil]

Scary stuff! But then, we do know that a super-volcano eruption is possible sometime, somewhere, right? There was one in the 1800s in Indonesia, I think it was called Krakatoa. Caused there to be kind of no summer across some areas, such as the northern US that year.

Tambora wasn't a supervolcano.  It was a large, powerful volcano (the most powerful in the memory of civilized man), but at least an order of magnitude less than a true supervolcano like Yellowstone or Toba.

They have a measurement for volcanic eruptions called Volcanic Explosivity Index, which measures the volume of ejecta (as if it were dense rock) from the eruption and the height of the volcanic plume.  It goes by order of magnitude, and so a VEI 5 (the St. Helens eruption was a 5) produces on the order of 1 cubic kilometre of ejecta, whereas a VEI 6 (like Krakatoa in 1883) produces on the order of 10 km³, and a VEI 7 (Tambora) produces on the order of 100 km³.  VEI 8 is the realm of the supervolcanos , and they produce over 1000 km³ worth of ejecta.  Yellowstone's last eruption was barely a VEI 8.  On the other hand, there was an eruption in Indonesia 70,000 years ago that produced about 3,000 km³.  We haven't had a VEI 8 since we became civilized.