Hydrothermal Explosion Sends Tourists Running In Yellowstone ...

A small hydrothermal explosion occurred in Yellowstone National Park today (July 23, 2024) around ... [+] 10:00 AM MST in the Biscuit Basin thermal area.

A small hydrothermal explosion occurred in Yellowstone National Park on July 23, 2024 around 10 a.m. in the Biscuit Basin thermal area, about 2.1 miles (3.5 km) northwest of Old Faithful. Numerous videos of the event were recorded by visitors, seen running from the steam-and-debris explosion. The boardwalk was damaged, but there were no reports of injury.

Biscuit Basin, including the parking lot and boardwalks, is temporarily closed for visitor safety, and geologists are investigating the event.

Hydrothermal explosions occur when water suddenly flashes to steam underground. Small hydrothermal explosions happen almost annually someplace in Yellowstone National Park. Porkchop Geyser, in Norris Geyser Basin, experienced an explosion in 1989 witnessed by a group of visitors, and a small event in Norris Geyser Basin was recorded by monitoring equipment on April 15, 2024. An explosion similar to that of yesterday also occurred in Biscuit Basin on May 17, 2009.

But every few thousand years, large ones can also occur. The park is home to the largest-known hydrothermal explosion crater on Earth—Mary Bay, on the north side of Yellowstone Lake, is 1.5 miles (2.4 kilometers) across and formed about 13,000 years ago.

Yesterday's explosion does not reflect activity within the volcanic system, which remains at normal background levels. Hydrothermal explosions are not caused directly by magma rising towards the surface, but by groundwater heated by the constant flow of thermal energy from the underground.

A study published in 2021 in the journal Proceedings of the National Academy of Sciences shows that climate also plays a role. In the spring and early summer, with melting snow and rain, water fills the underground reservoir, providing more hot water to erupt more frequently. During winter, with less water, lower groundwater pressure refills the reservoir more slowly, leading to longer periods between eruptions. Long-term activity is likely controlled by the rising or falling groundwater table with drought periods reflecting a decrease in geyser activity.

Additional material provided by USGS Volcanoes.