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The Mountain West News Bureau is a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, KUNR in Nevada, the O'Connor Center for the Rocky Mountain West in Montana, KUNC in Colorado, KUNM in New Mexico, with support from affiliate stations across the region. Funding for the Mountain West News Bureau is provided in part by the Corporation for Public Broadcasting.

The World’s Tallest Active Geyser Is Acting Up

Steamboat Geyser is located in the Norris Geyser Basin of Yellowstone National Park.
Steamboat Geyser is located in the Norris Geyser Basin of Yellowstone National Park.

Old Faithful gets all the attention, but a geyser called Steamboat is the world’s tallest active geyser. And it’s acting a little odd.

The geyser, located in Yellowstone National Park’s Norris Geyser Basin, can shoot water higher than 300 feet in the air.

“Typically, Steamboat eruptions are much, much larger than what we see from Old Faithful -- easily 10 times as what Old Faithful puts out in terms of volumes of water,” says Mike Poland, a geophysicist with the Yellowstone Volcano Observatory.

According to the National Park Service, the geyser’s major blasts are powerful enough to break mature lodgepole pine trees and loud enough to wake up campers sleeping a mile away. They also appear to drain the water out of surrounding springs.

But the geyser doesn’t erupt very often. Sometimes it’s quiet for a couple years in between major eruptions. It once went still for 50 years straight. But now, Poland says, Steamboat Geyser has erupted three times in the last six weeks.

Steamboat Geyser lets off steam in November 2017.
Credit Jacob W. Frank / National Park Service
Steamboat Geyser lets off steam in November 2017.

Yellowstone sits atop a caldera, also called a supervolcano. Scientists have estimated its body of magma is more than 40 miles across and 3 to 10 miles below the surface. The magma heats up underground rocks, which heat up water in the ground. That water eventually explodes at the surface when it boils, expanding as it turns to steam. The water heats and explodes at different rates, Poland says, depending on factors like if water collects in underground pockets. Earthquakes can shift such “plumbing,” changing geyser patterns.

Maybe, Poland says, something about Steamboat’s plumbing is now changing. But Poland isn’t prepping his doomsday bunker.

“No, no. This is what geysers do. They erupt,” he says, and they often do so unpredictably. Old Faithful, which erupts on a regular basis, is actually the outlier.

In fact, Poland says, the real sign of an impending supervolcano eruption would not be unusual eruption patterns; it would be the opposite.

“If we saw geysers stop erupting and the water just going away, that would be a change that would be much more worrisome than geysers erupting,” he says. “That might be a sign that magma was ascending and it was boiling off all the water that was in the subsurface.”

He says we’d probably notice other things first, like a whole bunch of really big earthquakes and large swaths of land inflating with material from the deep.

Yellowstone’s supervolcano last erupted about 70,000 years ago, a "pretty benign" flow of lava, as Poland puts it. The last catastrophic explosion was 631,000 years ago. Scientists don’t expect another one anytime soon.

This story was produced by the Mountain West News Bureau, a collaboration between Wyoming Public Media, Boise State Public Radio in Idaho, Yellowstone Public Radio in Montana, KUER in Salt Lake City and KRCC and KUNC in Colorado. 

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