There’s always talk on social media when a news alert or article about Yellowstone comes out. People have a tendency to feel anxiety that this giant caldera is overdue for an eruption, and those eruptions tend to be devastating. But the likelihood that it will erupt on any given day is very, very small.

However, volcanic eruptions are not the only natural hazard at Yellowstone. Even more common are hydrothermal eruptions, which have a less far-reaching impact but can cause local damage. And while caldera eruptions occur on the order of hundreds of thousands of years, larger hydrothermal eruptions occur on the scale of thousands of years. That timescale is still not enough to worry about, but the timing and impact are something we need to understand, and scientists just haven’t spent a lot of time studying the effects. Until now.

A new study in the Geological Society of American Bulletin analyzes cores taken from under Yellowstone Lake in a pair of known craters: Mary Bay and Elliot’s craters. The Mary Bay explosion occurred 13,000 years ago, resulted in a 2.5-kilometer-wide crater, and while the effects on land had been previously studied, the extent of the crater and deposits were not known. As for Elliot’s crater, that explosion occurred 8,000 years ago and left a 700-meter crater, completely submerged under the lake.

Several discoveries from this research were especially interesting. One, the deposits from these eruptions were more broadly distributed both underwater and on land than previously thought. Two, the Mary Bay explosion was caused by a seismic event that dropped the lake level 14 meters and resulted in a tsunami. And three, the cores revealed smaller deposits from previously unknown, more recent hydrothermal explosions.

This research was led by Lisa Morgan.

More Information

GSA press release

“The dynamic floor of Yellowstone Lake, Wyoming, USA: The last 14 k.y. of hydrothermal explosions, venting, doming, and faulting,” L.A. Morgan et al., 2022 June 7, GSA Bulletin