Under Yellowstone, Magma Pocket 20% Larger Than Thought

Richard A. Lovett in San Francisco
for National Geographic News
December 15, 2009

The huge column of molten rock that feeds Yellowstone's "supervolcano" dives deeper and fills a magma chamber 20 percent bigger than previous estimates, scientists say.

Animation of Yellowstone's plume in 3-D


The finding, based on the most detailed model yet of the region's geologic plumbing, suggests that Yellowstone's magma chamber contains even more fuel for a future "supereruption" than anyone had suspected.

The model shows that a 45-mile-wide (72-kilometer-wide) plume of hot, molten rock rises to feed the supervolcano from at least 410 miles (660 kilometers) beneath Earth's surface.

The deepest part of the plume actually sits beneath the town of Wisdom, Montana, about 150 miles (241 kilometers) from Yellowstone National Park (see map).

But the steady flow of hot rock in Earth's upper mantle causes the plume to drift to the southeast, where it fills a magma chamber that sits just 3.7 to 10 miles (5.9 to 16 kilometers) beneath Yellowstone.

(Take a virtual dive down Yellowstone's plume.)

Other new data show that Yellowstone's magma chamber extends 13 miles (21 kilometers) farther to the northeast than previously thought.

But that doesn't mean the region is on the verge of exploding, said study leader Robert Smith, a geophysicist at the University of Utah in Salt Lake City.

"This [plume] is the source of Yellowstone's volcanic system," he said. "It doesn't say anything about the probability of a big eruption. [That is] a very rare thing."

Yellowstone's Eruptions

Scientists had already known that Yellowstone is a volcanic hot spot, and that within the past two million years, the region has seen three mammoth eruptions at intervals of about 700,000 years.

Continued on Next Page >>


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