'Clogged-up' underground system caused Yellowstone’s powerful hydrothermal explosion

The 2024 explosion hurled large rocks and debris hundreds of feet into the air, sending park visitors on a nearby boardwalk scrambling for safety.

A clogged-up underground system caused the powerful hydrothermal explosion at Yellowstone’s Black Diamond Pool last summer, according to the U.S. Geological Survey (USGS). Minerals had sealed off channels beneath the pool in Biscuit Basin, trapping pressure that eventually led to the blast.

On July 23, 2024, the explosion hurled large rocks and debris hundreds of feet into the air, sending park visitors on a nearby boardwalk scrambling for safety. Thankfully, no injuries occurred, but the boardwalk was severely damaged and remains closed.

"By closely examining rocks that flew out, we've learned that the explosion occurred when the shallow hydrothermal system became sealed by minerals that had been transported in the water," the USGS wrote in a news release. "The minerals clogged up the plumbing system and that allowed pressure to build in shallow levels just beneath the surface. An explosion was inevitable."

Since then, the area has remained geologically active. Muddy eruptions in November 2024 and January 2025 sent water several feet into the air. In May 2025, another larger eruption shot water 20 to 30 feet high, with smaller events following.

Meanwhile, in Norris Geyser Basin, a new thermal pool formed gradually between late 2024 and early 2025. Unlike the sudden Black Diamond explosion, this feature developed through a series of smaller hydrothermal events, creating a roughly 13-foot-wide pool near “Tree Island.”

Park officials continue to monitor these areas closely, as Yellowstone’s geothermal activity remains dynamic and unpredictable.

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