Scientists seek clues to what triggered past Yellowstone 'supervolcano' eruptions

Correction: An earlier version of this story misstated the findings of the recent research. The story has been updated and expanded. 

Underneath Yellowstone National Park lies a "supervolcano," one that blows its top with a massive supereruption every few hundred thousand years. 

The most recent "supereruption" struck about 630,000 years ago, shaking the region and creating the Yellowstone caldera, a bowl 40 miles wide that forms much of the park. There have been several smaller eruptions since then. 

Now scientists are looking for clues about what triggered that eruption, and whether those signals could be used to detect possible future supereruptions. 

Researchers discovered that the forces that drive these supereruptions can occur much more rapidly than volcanologists previously anticipated: in the span of decades, not millenniums. 

Christy Till, an Arizona State University geologist, graduate student Hannah Shamloo, and other researchers from Arizona State analyzed minerals in fossilized ash from that most recent supereruption. They presented their research at a recent volcanology conference, but it has not been published in a peer-reviewed scientific journal.

“We expected that there might be processes happening over thousands of years preceding the eruption,” Till told The Times.  Instead, the crystals revealed an increase in temperature and a change in composition that had happened more quickly.

 There is no indication, however, that such an eruption is imminent, or that the volcano is "due" for an eruption. "The probability of such a large eruption occurring in any given year is 1 in 730,000," Till said. 

According to The New York Times, Shamloo analyzed crystals that recorded changes in temperature, pressure and water content beneath the volcano — much like a set of tree rings gives clues to past climates.

“It’s shocking how little time is required to take a volcanic system from being quiet and sitting there to the edge of an eruption,” Shamloo told The Times, cautioning that more research is necessary before definite conclusions can be drawn.

Fortunately, even if there was a "supereruption," the effects would likely not be catastrophic.

As for the worst-case scenario, even previous Yellowstone supereruptions did not cause extinctions, and ash fallout on the other side of the continent was minimal, according to the U.S. Geological Survey. 

There is no way a volcanic eruption could end all life on Earth, Till said.  

In fact, the Yellowstone supervolcano has erupted at least 23 times since the last "supereruption." All of those have been rather small lava flows. So if it did erupt, it would likely be one of those small eruptions, Till said. 

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