Hydrothermal Explosion Rocks Yellowstone’s Biscuit Basin, Damages Boardwalk

A hydrothermal explosion in Yellowstone National Park damaged a boardwalk and sent debris several stories into the air Tuesday morning in the Biscuit Basin area northwest of Old Faithful, according to Michael Poland, Scientist-in-Charge at the U.S. Geological Survey’s Yellowstone Volcano Observatory.

The explosion, which Poland described as “small,” occurred around 10 a.m. about 2.1 miles northwest of Old Faithful, likely in the Black Diamond Pool in Biscuit Basin. Fortunately, no injuries have been reported so far.

Videos posted online by witnesses show several people on the boardwalk near the explosion site and the aftermath with debris scattered across the area and a damaged boardwalk.

For safety reasons, Biscuit Basin’s parking lot and boardwalks are temporarily closed. Yellowstone National Park geologists are investigating the explosion but have stated that there is no unusual volcanic activity in the area.

“Monitoring data show no changes in the Yellowstone region. Today’s explosion does not reflect activity within the volcanic system, which remains at normal background levels of activity,” Poland said in a statement. “Hydrothermal explosions like today’s are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface.”

Poland explained that these types of explosions occur when water quickly changes to steam underground and are “relatively common” in Yellowstone National Park. Similar explosions have happened before in the park, including one in Biscuit Basin in May 2009 and a smaller one in Norris Geyser Basin on April 15. Porkchop Geyser in Norris Geyser Basin also exploded in 1989.

Hydrothermal explosions can send boiling water, steam, mud, and rock into the air, reaching heights of up to 1.2 miles, according to the U.S. Geological Survey. A 2018 report indicated that large hydrothermal explosions happen on average every 700 years, with at least 25 craters in the park measuring at least 328 feet wide.

“Although large hydrothermal explosions are rare events on a human time scale, the potential for additional future events of this sort in Yellowstone National Park is not insignificant,” the report states. “Based on the occurrence of large hydrothermal explosion events over the past 16,000 years, an explosion large enough to create a 328-foot-wide crater might be expected every few hundred years.”

According to the National Park Service, Black Diamond Pool erupted black, murky water following an earthquake in July 2006 and experienced “several explosive eruptions” in the days after. However, eruptions have been “infrequent” since then, with the pool’s average temperature at 148.5 degrees Fahrenheit.

The Yellowstone Volcano Observatory has promised to release more information as it becomes available.