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US Supervolcanoes: Yellowstone-Check, Utah-Check, Wait… Utah?

December 12, 2013
Image Caption: BYU geologists Eric Christiansen (left) and Myron Best at the site of the discovery. Credit: Brigham Young University

[ Watch the Video: Add Another Supervolcano To North America's List ]

Brett Smith for redOrbit.com – Your Universe Online

Geologists from Brigham Young University in Utah have found evidence of a massive supervolcano near the Utah-Nevada border that had a massive eruption around 30 million years ago some 5,000 times larger than the Mount St. Helens eruption in 1980, according to a new report published in the journal Geosphere.

“In southern Utah, deposits from this single eruption are 13,000 feet thick,” said study author Eric Christiansen, an associate professor of geology at BYU. “Imagine the devastation – it would have been catastrophic to anything living within hundreds of miles.”

While dinosaurs had long been extinct when this eruption happened, North America at the time was home to a wide range of mammals, reptiles and plant life. The researchers said this massive eruption would have blocked out the sun, potentially disrupting the life cycles of many of these organisms.

To confirm the supervolcano’s existence, the researchers examined the thickness of the volcanic flow deposits. The team also used radiometric dating, X-ray fluorescence spectrometry and chemical analysis of the minerals to determine the volcanic ash at the site was all from the same eruption.

Believed to have occurred near Wah Wah Springs, Utah – the eruption buried a vast area extending from central Utah to central Nevada. The team said they even found evidence of the eruption as far away as Nebraska. The BYU scientists also found evidence of fifteen other eruptions and 20 large calderas related to the same supervolcano.

Despite their enormous size and impact on the Earth, millennia of erosion slowly hide supervolcanoes in plain sight.

[ Watch the Video: Massive Ancient Supervolcano Discovered in Utah ]

“The ravages of erosion and later deformation have largely erased them from the landscape, but our careful work has revealed their details,” Christiansen said. “The sheer magnitude of this required years of work and involvement of dozens of students in putting this story together.”

Unlike Mount St. Helens, supervolcanoes are different from the more familiar “straddle” volcanoes because they aren’t cone-shaped mountains with a single hole that spouts magma and other volcanic material.

“Supervolcanoes, as we’ve seen, are some of Earth’s largest volcanic edifices, and yet they don’t stand as high cones,” said Christiansen. “At the heart of a supervolcano instead, is a large collapse.”

A supervolcano forms when a massive pool of magma builds below the surface and pushes upward – forming a large dome. Eventually the surface breaks, starting a massive eruption, releasing the magma and forming a bowl-shaped depression a few miles deep, known as a caldera.

There are still active supervolcanoes today, such as the one found in Yellowstone National Park in Wyoming. The caldera of this supervolcano is about the same size as the Wah Wah Springs caldera, which was approximately 25 miles across and 3 miles deep when it was first created.

“One of the things that geologists are always trying to piece together is the history of the Earth,” Christiansen said in a web video. “The history of the Earth has been punctuated by catastrophic events. Identifying one of those that occurred here in western Utah will help us piece together this long chain of events that are part of Earth’s history.”


Source: Brett Smith for redOrbit.com - Your Universe Online



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