'Supervolcanoes' said to have short fuses

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NASHVILLE, May 31 (UPI) -- "Supervolcano" eruptions with potential to cause widespread extinctions of life may have surprisingly short fuses, U.S. earth scientists say.

Such super-eruptions are more than 100 times larger than ordinary volcanic eruptions like Mount St. Helens and emit tremendous flows of super-heated gas, ash and rock capable of blanketing entire continents and plunging the global climate into decade-long volcanic winters, they said.

Geologists have generally held that a super-eruption is produced by a giant pool of magma that forms a couple of miles below the surface and then simmers for 100,000 to 200,000 years before erupting.

However, a new study led by researchers at Vanderbilt University suggests otherwise, a university release reported Thursday.

"Our study suggests that when these exceptionally large magma pools form they are ephemeral and cannot exist very long without erupting," said Guilherme Gualda, a professor of earth and environmental sciences.

They may only exist for a few thousand years, or even just a few hundred years, before erupting, he said.

These giant magma pools tend to be shaped like pancakes and are 10 to 25 miles in diameter and one half to three miles deep.

While no such giant magma body currently exists capable of producing a super-eruption, the researchers say they believe this may be because these magma bodies exist for a relatively short time rather than persisting for hundreds of thousands of years as previously thought.

"The fact that the process of magma body formation occurs in historical time, instead of geological time, completely changes the nature of the problem," Gualda said.

Instead of concluding that there is virtually no risk of another super-eruption for the foreseeable future because there are no suitable magma bodies, geologists need to regularly monitor areas where super-eruptions are likely, such as Yellowstone, to provide advanced warning if such a magma body begins to form, he said.