Explosion at Yellowstone National Park damages boardwalk. Here’s what’s next

The Biscuit Basin area of Yellowstone National Park is now closed after a hydrothermal explosion took place Tuesday.

The explosion near Sapphire Pool damaged a boardwalk while park guests ran away to safety. No injuries were immediately reported. Several guests videoed the explosion and posted the videos to social media .

“Biscuit Basin as well as its boardwalks and parking lots are closed for visitor safety as park geologists investigate what occurred,” USA Today reported.

The explosion erupted in the Biscuit Basin thermal area, which is about 2 miles away from Old Faithful, and it “appears to have originated near Black Diamond Pool,” per a release .

What is a hydrothermal explosion?

According to the U.S. Geological Survey , “Hydrothermal explosions are violent and dramatic events resulting in the rapid ejection of boiling water, steam, mud, and rock fragments.”

The scientist-in-charge of the Yellowstone Volcano Observatory explained, “These things can happen somewhat randomly,” Mike Poland told Jackson Hole New s. “They are episodes of water flashing to steam underground. Sometimes they can be triggered by earthquakes. Often they are just the plumbing system underground. It’s the randomness of the hydrothermal system.”

Hydrothermal explosions are typically “rare events on a human time scale...” per the release . “Based on the occurrence of large hydrothermal explosion events over the past 16,000 years, an explosion large enough to create a 100-(meter)- (328-ft-) wide crater might be expected every few hundred years,” it added.

Here are other hydrothermal explosions that have taken place in the park in recent years, according to a release .

• Porkchop Geyser — “experienced an explosion in 1989.”
• Norris Geyser Basin — “a small event in North Geyser Basin was recorded by monitoring equipment on April 15, 2024.”
• Biscuit Basin — “An explosion similar to that of today also occurred in Biscuit Basin on May 17, 2009.”