Researchers have discovered two ancient supereruptions associated with the Yellowstone hot spot track, including what they believe was the volcanic province’s “largest and most cataclysmic event,” according to a new study.

Two volcanic supereruptions associated with the hot spot that today fuels the geysers, mudspots and fumaroles in Yellowstone National Park rocked what is now Idaho and Nevada between 12 million and 8 million years ago, according to the study published Wednesday in Geology, the peer-reviewed publication of the Geological Society of America.

The first supereruption, known as the McMullen Creek supereruption, impacted a nearly 4,600-square-mile stretch of modern-day Idaho and the second, known as the Grey’s Landing supereruption, impacted nearly 8,900 square miles of Idaho and Nevada.

The supereruptions released clouds of searing hot gas and ash at temperatures greater than 900 Celsius that spread at supersonic speed, sterilizing the land surface, according to Thomas Knott, a volcanologist at the University of Leicester and the paper’s lead author.

“It welded to the landscape,” Knott told USA TODAY. “An area the size of the state of New Jersey would’ve been enameled in solid black glass.”

Both of the newly discovered supereruptions occurred during the Miocene period, defined as the time period between 23 million to 5.3 million years ago. During this period, Knott said super eruptions occurred on average every 500,000 years.

In comparison, in the past 3 million years only two supereruptions have taken place so far in what is now Yellowstone National Park, making the recurrence rate just once every 1.5 million years. Researchers also found the ancient supereruptions were significantly hotter and of a much higher magnitude than many others that originated from Yellowstone. 

“We believe that these unequivocal decreases in temperature, size and frequency allow us to at least pose the question: Is Yellowstone hot spot starting to dwindle? Has it been dwindling since approximately 9 million years ago?” Knott said.

Knott said this new data raises questions about the lifespan of volcanic hot spots, wondering whether hotspots hit a “midlife crisis” where activity slowly dwindles before their death. Researchers won’t know definitively until the hot spot dies, although Knott said it’s almost impossible to predict when that may occur.

“Yellowstone is very much active and isn’t showing any evidence of dying out entirely,” he said. “But perhaps if we can better understand the full life span if you will of a hot-spot-related supervolcanic province we will understand more about what their role has been in shaping the climate and processes of our planet throughout geological time.” 

Knot said the data may also allow researchers to use patterns of the past to inform predictions about present day, but noted that it’s difficult to predict when Yellowstone might erupt again. Because the last supereruption was 630,000 years ago, it may be up to 900,000 years before another eruption of this scale occurs, according to Knott.

But this estimate, Knott added, “should not be taken as gospel,” and researchers like those at the U.S. Geological Survey must do continuous monitoring in the region.

“We don’t know,” he said. “It could be tomorrow, it could be hundreds of thousands of years.”

Knot said hopes to do more research to get a better understanding of why the hot spot appears to be dwindling and look further back in time to determine if there are even larger supereruptions in the hot spot’s history.

Follow N’dea Yancey-Bragg on Twitter: @NdeaYancey-Bragg

This article originally appeared on USA TODAY: Yellowstone National Park hot spot fueled two ancient supereruptions





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