Another blast hits Yellowstone. What just happened at Biscuit Basin?

Another hydrothermal explosion occurred at Yellowstone National Park, pointing to the unpredictable nature of the park's vast underground thermal system and providing scientists with a rare opportunity to study one of the area's most dangerous natural hazards.

The small explosion happened at about 5:09 a.m. local time on June 13 in Biscuit Basin, according to a report from the U.S. Geological Survey's Yellowstone Volcano Observatory.

No injuries were reported, largely because Biscuit Basin has remained closed since a much larger hydrothermal explosion near Black Diamond Pool in July 2024. But the latest event created new vents, sent hot water and sediment into the Firehole River and eventually formed a new boiling pool where solid ground had existed just days earlier.

Scientists say the incident highlights both the hazards of Yellowstone's thermal areas and the challenges of predicting when hydrothermal explosions might occur.

What happened at Biscuit Basin?

Monitoring equipment detected unusual seismic activity and low-frequency acoustic signals, known as infrasound, coming from the direction of Black Diamond Pool shortly after 5 a.m. on June 13.

Later that morning, park staff noticed something unusual: a light-gray, milky plume flowing through the Firehole River downstream from Biscuit Basin. New runoff channels leading from the basin into the river were also visible.

A camera installed in 2025 captured the source of the disturbance, recording a dark-colored steam plume erupting from the ground north of Black Diamond Pool at nearly the same time the monitoring equipment registered the event.

When geologists arrived the following day, they found three groups of newly formed vents that allowed near-boiling underground water to suddenly reach the surface. As the water rapidly turned to steam, it triggered a hydrothermal explosion.

New vents and a new boiling pool

Scientists documented several new features left behind by the blast.

One crack north of Black Diamond Pool stretched about 61 feet long and up to 5 feet wide. Another vent measured roughly 49 feet long. Water temperatures in the area ranged from 185 to 200 degrees Fahrenheit, near the boiling point at Yellowstone's elevation.

The explosion itself was considered relatively small. Rocks thrown from the vents landed only a few yards away, indicating far less force than the July 2024 explosion.

During a return visit days later, geologists discovered an entirely new pool measuring about 21 feet by 17 feet. Filled with gray, silty water, the pool was vigorously boiling and producing loud thumping sounds caused by steam bubbles forming and collapsing beneath the surface.

Camera footage recorded June 18 showed the pool occasionally spouting water 20 to 30 feet into the air before returning to an active boil.

Why scientists are paying close attention

Hydrothermal explosions occur when pressurized hot water trapped underground suddenly flashes into steam. While smaller than volcanic eruptions, they can be extremely dangerous because they often happen with little warning.

Researchers have installed temporary seismic monitoring stations in Biscuit Basin and are now analyzing data collected before the explosion. Because the event occurred only about 328 feet from a monitoring station installed in 2025, scientists believe they may have captured valuable clues that could reveal whether warning signs occurred beforehand.

The June 13 explosion offers what researchers describe as an unprecedented opportunity to better understand hydrothermal hazards at Yellowstone and potentially improve future detection efforts.

According to the U.S. Geological Survey, Yellowstone sits on top of a large volcanic system called the Yellowstone Caldera. The agency says heat from magma deep underground fuels the park’s geysers, hot springs and other hydrothermal features by heating groundwater circulating beneath the surface. Despite public concern, the U.S. Geological Survey says the system is not “overdue” for a major eruption, noting that volcanic activity does not follow predictable schedules and that there is no evidence an eruption is imminent.

Reporter Anthony Thompson can be reached at [email protected], or on X @athompsonUSAT