Yellowstone volcano coming in distant future?

'Old Faithful' is one of the geysers at Yellowstone caused by geologic 'hot spots' created by molten rock rising from the earth's mantle

By Peter Dykstra
CNN

MADISON, Wisconsin (CNN) -- Yellowstone visitors may not have to pack up the picnic basket and flee for another million years, but University of Wisconsin geologists say conditions there could evolve to the point where a massive volcano erupts at the National Park site.

But it won't likely take place soon. While most volcanologists regard the area to be "dormant" in terms of its volcanic potential, the scientists say the eruption may not take place for a million years, though it could occur within 100,000 years.

Scientists Ilya Bindeman and John W. Valley analyzed crystals of zircon and quartz, discovering geologic clues of massive eruptions at Yellowstone in a regular pattern.

The scientists estimate that major eruptions took place two million years ago, then 1.3 million and 600,000 years ago.

The zircon and quartz crystals provide a geologic time capsule -- allowing the scientists to estimate volcanic activity by analyzing the amounts of trapped air and water within the crystals, and also by analyzing the patterns of volcanic re-melting of the crystals.

'Catastrophic' potential

The geologic "hot spot" beneath Yellowstone, which causes its famous geysers and hot springs, is created by a plume of magma -- molten rock -- rising from the earth's mantle.

"These magmas usually erupt in a very catastrophic way," said Bindeman.

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The scientists speculate that Yellowstone's spectacular geo-thermal landscape was even more dramatic prior to the last eruption.

The scientists say that the largest of the Yellowstone eruptions occurred two million years ago, and spread ash over more than half the current-day United States -- an area stretching from Houston and Kansas City to Seattle and Los Angeles. By contrast, the largest recent eruption at Mount St. Helen's, Washington, in 1980, dusted the city of Portland, Oregon, 60 miles away, and left an ash field slightly more than 20 miles wide.

Bindeman and Valley published their work in a series of papers in journals including Geology and the Journal of Petrology.