Supervolcano Under Yellowstone is Twice as Large as Previously Thought

Scientists have discovered that the Yellowstone magma pocket is close to the size when the supervolcano last erupted, 640,000 years ago.
Yellowstone Clypsydra Geyser in the Lower Geyser Basin

The Clypsydra Geyser in Yellowstone National Park, home of a large underground supervolcano

What’s gurgling beneath the surface of Yellowstone National Park? You guessed it: Magma. And the makings of a supervolcano.

The magma pocket, which scientists have recently found to be 2.5 times larger than previously thought, measures 55 miles by 20 miles on each side and about 6 miles deep. That’s close to the size of the pocket when the supervolcano last erupted, 640,000 years ago.

"What we're seeing now agrees with the geologic data that we have about past eruptions," James Farrell, a member of the analysis team of scientists from the University of Utah that recently presented the findings at the American Geophysical Union, told National Geographic. "And that means there's the potential for the same type of eruption that we've seen in the past."

Researchers believe that an eruption empties the magma pocket, which then refills again over hundreds of thousands of years.

The recent findings however, do not necessarily mean that the magma pocket has grown in recent years. Farrell clarifies, “That's not to say it's getting any bigger. It's just that our ability to see it is getting better.”

If the supervolcano erupts, scientists predict that magma will spew more than 240 cubic miles from the eruption site, covering sections of Montana, Idaho and Wyoming. Global climate repercussions are also expected with ash and pulverized rock particles shooting into the atmosphere and drifting back down to Earth.

"You'll get ashfall as far away as the Great Plains, and even farther east," Farrell said.

Any volcanic material that remains in the atmosphere will make it difficult for the sun’s rays to penetrate down to the ground. As a result, it’s predicted that temperatures across the world will decrease.