Biscuit Basin eruption
Hydrothermal Explosion Sends Yellowstone Visitors Running
Biscuit Basin, Yellowstone National Park — A dramatic hydrothermal explosion at Yellowstone National Park's Biscuit Basin on Tuesday morning sent visitors scrambling for safety. The explosion, which occurred at approximately 10:19 a.m. local time, spewed boiling water, steam, and debris into the air, causing significant damage to the park's infrastructure but fortunately resulting in no injuries.
The eruption took place near the Sapphire Pool, a well-known thermal feature located about two miles northwest of the iconic Old Faithful Geyser. According to the National Park Service (NPS), the explosion was a sudden and violent event, characteristic of hydrothermal activity in the region. The force of the eruption destroyed sections of the boardwalk and sent debris flying, prompting immediate closure of the Biscuit Basin area for safety reasons.
Witnesses described the explosion as both terrifying and awe-inspiring. Steve March, a visitor from California, was on the boardwalk with his family when the eruption occurred. "We were walking toward Jewel Geyser when our guide pointed out a sudden increase in steam from Sapphire Pool," he recounted. "Moments later, there was a massive explosion, and rocks and black water shot hundreds of feet into the air. Our guide told us to run, and we grabbed our kids and made our way to solid ground as quickly as we could."
Park rangers and geologists from the United States Geological Survey (USGS) were on the scene within minutes to assess the damage and ensure the safety of visitors. The NPS confirmed that no injuries were reported, although the extent of the damage to the boardwalk and surrounding areas is still being evaluated. Photos shared by the park on social media show the boardwalk covered in debris, with sections of the structure destroyed.
Hydrothermal explosions occur when water trapped underground is rapidly converted to steam due to a decrease in pressure, causing a violent release of steam, water, and rock fragments. These events, while relatively common in Yellowstone, are notoriously difficult to predict. The USGS likened the explosions to a pressure cooker, noting that they often occur without warning.
Hydrothermal explosions are not new to Yellowstone. Similar events have been recorded in the past, including an explosion at Porkchop Geyser in Norris Geyser Basin in 1989 and another in the same Biscuit Basin area in 2009. The most recent explosion prior to Tuesday's event occurred in Norris Geyser Basin in April 2024.
Despite the dramatic nature of these explosions, they do not indicate an increase in volcanic activity. The USGS and NPS both emphasized that the volcanic system in Yellowstone remains at normal background levels of activity. "Hydrothermal explosions are an underappreciated hazard that we've been emphasizing for years," the USGS stated. "They are not caused by magma rising towards the surface and are not a sign of impending volcanic eruptions."
Videos captured by visitors show the chaos and urgency of the moment. People can be seen fleeing the boardwalk as the eruption intensified, with some shouting warnings to others. "Back up!" and "Holy cow!" were among the exclamations heard as the crowd hurried to safety. The March family, who captured the eruption on video, described the aftermath as resembling a warzone, with the Black Diamond Pool looking like a muddy crater surrounded by debris.
In response to the explosion, the NPS has temporarily closed Biscuit Basin, including the parking lot and boardwalks, until the area is deemed safe for visitors. The Grand Loop Road remains open. Park staff, along with USGS geologists, are closely monitoring the situation and will provide updates as more information becomes available.
Hydrothermal explosions, while a natural part of Yellowstone's dynamic geothermal landscape, serve as a stark reminder of the powerful forces at play beneath the park's surface. Visitors are urged to stay informed about safety guidelines and to respect park closures and warnings.
As Yellowstone continues to captivate and challenge both scientists and tourists, the recent explosion at Biscuit Basin underscores the need for ongoing vigilance and preparedness in one of the world's most geologically active regions.