Reawakened geyser does not foretell Yellowstone volcanic eruptions

When Yellowstone National Park's Steamboat Geyser -- which shoots water higher than any active geyser in the world -- reawakened in 2018 after more than three years of dormancy, some speculated that it was a harbinger of possible explosive volcanic eruptions in the surrounding geyser basin.

These hydrothermal explosions can hurl mud, sand and rocks into the air and release hot steam, endangering lives. Such an explosion on White Island in New Zealand in December 2019 killed 22 people.

A new study throws cold water on the idea of possible explosive volcanic eruptions in Yellowstone, finding few indications of the underground magma movement that would be a prerequisite to an eruption. The geysers sit just outside the nation's largest and most dynamic volcanic caldera, but no major eruptions have occurred in the past 70,000 years.

The U.S. National Science Foundation-funded study is published in Proceedings of the National Academy of Sciences.

"Hydrothermal explosions -- basically hot water exploding because it comes into contact with hot rock -- are among the biggest hazards in Yellowstone," said Michael Manga, a geoscientist at the University of California, Berkeley, the study's senior author. "They are very hard to predict. It’s not clear if there are any precursors that would allow you to provide warnings."

Manga and his team found that while the ground around the geyser rose and seismicity increased somewhat before the geyser reactivated, no other dormant geysers in the basin have restarted.

The temperature of the groundwater propelling Steamboat's eruptions has not increased. And no sequence of Steamboat eruptions other than the one that started in 2018 occurred after periods of high seismic activity.

"We don't find any evidence that there is a big eruption coming," Manga said. "I think that is an important takeaway."