Yellowstone National Park in Wyoming has closed an area of the park for the rest of the summer after a hydrothermal explosion sent steam and debris flying hundreds of feet into the air on July 23, park officials said.
Videos on social media showed some park visitors running away from the dark steam plume near Sapphire Pool in Biscuit Basin, about two miles northwest of Old Faithful, shortly after 10 a.m. on July 23, according to officials at Yellowstone National Park. The boardwalk suffered damage but there were no reported injuries.
“Yellowstone National Park has closed Biscuit Basin for the remainder of the 2024 season for visitor safety,” the National Park Service said. “Grand Loop Road remains open to vehicles, and other nearby thermal basins, like Black Sand Basin, are open.”
The U.S. Geological Survey (USGS) at the Yellowstone Observatory said hydrothermal explosions are relatively common at Yellowstone Park. However, many of these explosions take place in the backcountry, where they go largely unnoticed.
This week’s explosion was not caused by volcanic activity, according to the USGS.
“Hydrothermal explosions like that of today are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface,” the USGS said on July 23, adding that there have been no changes in the volcanic system.
An explosion similar to that on July 23 took place in the Biscuit Basin in May 2009. In 1989, an explosion occurred in Norris Geyser Basin, and a small event was recorded in the same area on April 15 this year.
These types of explosions, which are caused when water suddenly flashes to steam underground, are difficult to predict and can happen at any time.
The July 23 explosion affected both the Black Diamond Pool and Black Opal Pool, and “while they remain distinct features, the shape of Black Diamond has changed somewhat,” according to the park’s update.
“Both pools are murky due to debris, and the unstable ground around the edges occasionally slides into the water,” park officials said. “Just after the eruption, Black Diamond Pool exhibited minor roiling and water spouting.”
Hours later, the roiling turned to occasional bursts of hot water, reaching about eight feet high.
By the morning of July 24, both pools were overflowing into the Firehole River.
The Park Service and the USGS are continuing to investigate the explosion.
