Yellowstone’s last supereruption, which occurred 631,000 years ago, was not a single big explosion. Instead, new research suggests it was a series of eruptions, or multiple eruptions ejecting volcanic material in rapid succession.
According to the United States Geological Survey’s (USGS) Yellowstone Volcano Observatory’s 2022 Annual Report, released on May 4, field work over the past year has revealed that “the formation of the Yellowstone caldera was previously thought to be It was far more complex than it was,” said the new geological evidence. A caldera is a large crater that forms after the collapse of a volcano after an eruption.
Yellowstone is one of the world’s largest volcanic systems. It sits above one of Earth’s “hot spots,” regions within the mantle where hot plumes rise to form volcanoes in the upper crust. In the last three million years, he has had three caldera-forming eruptions. One is the Huckleberry Ridge Tuff eruption 2.1 million years ago. Eruption of Mesa Falls 1.3 million years ago. And the eruption of Lava Creek 631,000 years ago.
What is a supereruption?
The Huckleberry Ridge Tuff and Lava Creek eruption is considered a supereruption because it ejected more than 240 cubic miles (1,000 cubic kilometers) of material. The latter was involved in the formation of the Yellowstone Caldera. Mesa Falls’ eruptive volume is he 67 cubic meters (280 cubic kilometers), so it’s still about ten times as big as the 1980 Mount St. Helens eruption, but it’s not considered a supereruption.
Previous studies have shown that the Lava Creek supereruption did not occur suddenly. Deposits in the Sauer Creek Dome area east of the national park suggest at least one eruption preceded the giant explosion. The ignimbrite (volcanic rock formed by deposits of a hot mixture of material ejected during eruptions) found at the site had cooled completely before the major eruption of Lava Creek, which was marked on the map. rice field.
To better understand the timeline of the eruption, scientists remapped and collected samples at the Sour Creek Dome in 2022.
“It was always known that there were at least two geological units. [a volume of rock distinct from those surrounding it] Michael Poland, scientist in charge of the Yellowstone Volcano Observatory, told Live Science in an email. . And I don’t know what the time difference was, if at all. ”
So far, the research team has discovered four previously unrecognized Igniblight units at Sour Creek, suggesting the presence of at least four eruptive pulses. They also found two structures that appear to be craters that could be the source of these rocks.
“It could mean that some craters were active or there was a time gap between eruptions,” Poland said. “But we don’t yet have the data we need to answer these questions.”
In 2020, scientists discovered that the Huckleberry Ridge Tuff eruption, which erupted more than twice as much volcanic material as Lava Creek, was also a staged event. Analysis of rocks at the site showed that there were three separate eruptions, with weeks to months between the first two and years to decades between the second and third. is suggested.
Yellowstone volcano is not expected to erupt anytime soon. But the finding that Lava Creek eruptions may have followed a similar pattern to Huckleberry Ridge Tuff eruptions could give an idea of what to expect if Yellowstone erupted, and when. have a nature. “These massive caldera-forming eruptions may not be a single event at Yellowstone, but multiple stages,” Poland said.
Volcano researchers now plan to conduct a detailed study of the newly discovered units and their boundaries. This will allow a more detailed picture of what the Lava Creek eruption was like, and perhaps what caused it.
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