This article describes a dramatic mud eruption at Yellowstone’s Black Diamond Pool, explains how such events fit into the park’s hydrothermal landscape, reviews past explosive activity at the site, and outlines the deep volcanic history beneath the Yellowstone basin.
On the first day of winter 2025, visitors and observers witnessed a sudden, large mud eruption at Black Diamond Pool in Yellowstone National Park. The blast sent hot mud spraying outward, marking a clear hydrothermal event rather than a rainstorm or landslide. Officials emphasized that no one was hurt during the episode, but the sight underscored the unpredictable nature of Yellowstone’s geothermal areas.
U.S. Geological Survey volcanologists described the event with a single, evocative word: “Kablooey!” Video released by the agency captures mud bursting from the pool shortly before 9:23 a.m., sending a wet, steaming plume into the air. The eruption occurred in Biscuit Basin, roughly midway between two of the park’s best-known features, Old Faithful and the Grand Prismatic Spring.
“Kablooey!”
That’s the word U.S. Geological Survey volcanic experts used to describe a muddy eruption at Black Diamond Pool in Yellowstone National Park on Saturday morning.
Video shared by the USGS on social media shows mud spraying up and out from the pool just before 9:23 a.m. in Biscuit Basin about midway between park favorites Old Faithful and Grand Prismatic.
Other recent eruptions have mostly been audible and not visible, because they happened either at night or when the camera was obscured by ice.
The agency said the Black Diamond Pool was previously the site of a hydrothermal explosion, in July 2024, that sent rocks and mud flying hundreds of feet high and damaged a boardwalk. It prompted the closure of the area to visitors due to the damage and the potential for additional hazardous activity.
So-called dirty eruptions reaching up to 40 feet (about 12 meters) have occurred sporadically since then.
Park managers noted that this spot already had a documented hydrothermal explosion in July 2024 that hurled rocks and mud high enough to damage a boardwalk and prompt closures. Since that incident, the Black Diamond Pool area has produced intermittent “dirty eruptions,” some reaching as much as 40 feet in height. Those episodes show that hydrothermal systems can react violently even without an accompanying magmatic eruption from deep underground.
Nobody was injured in the winter eruption, a fortunate outcome given how quickly mud and ejecta can travel and how scalding thermal fluids sometimes accompany these blasts. Still, officials remind the public that geothermal areas remain hazardous and that closed zones exist for safety, not inconvenience. The presence of periodic eruptions increases the need for cautious management and clear visitor warnings around unstable features.
Yellowstone contains the most extensive concentration of hydrothermal features on Earth, with more than 10,000 individual manifestations; over 500 of those are geysers. That dense suite of hot springs, mud pots, fumaroles, and geysers is the visible expression of heat and fluids moving through shallow crust above a much deeper system. Hydrothermal explosions at the surface reflect pressure release and fluid-rock interactions rather than an imminent large-scale volcanic blast.
Underneath the surface, however, the Yellowstone basin sits above a very large volcanic system that has produced major caldera-forming eruptions in the geologic past. Scientists identify three major, caldera-forming eruptions known from roughly 2.1 million years ago, about 1.3 million years ago, and around 640,000 years ago. Those massive events produced thick tuff units and widespread ash fall across large swaths of North America.
The earliest of those episodes created the Huckleberry Ridge Tuff and spread ash across an area estimated at about 1.3 million square miles, an eruption far larger than more recent well-known events. The later Mesa Falls and Lava Creek eruptions were also enormous, each far exceeding the energy release of the 1980 Mt. St. Helens eruption. While these ancient eruptions loom large in Yellowstone’s history, the park’s modern-day hazards are dominated by hydrothermal activity and smaller-scale volcanic and seismic events.
Scientists stress that, although Yellowstone’s long-term volcanic potential is real, major caldera-forming eruptions are separated by hundreds of thousands to millions of years. Monitoring networks continuously track seismicity, ground deformation, gas emissions, and thermal behavior to provide early warning of significant changes. For now, observable risks are largely local: unstable ground, boiling fluids, and occasional hydrothermal explosions that can endanger anyone too close to an active feature.
Visitors and observers will likely continue to see sporadic hydrothermal activity in areas like Biscuit Basin, especially where past explosions indicate an active shallow hydrothermal plumbing system. Those events make Yellowstone both fascinating and, at times, hazardous, and they highlight the dynamic processes that shape the park’s landscape. Keep a respectful distance and heed closures; the ground beneath beautiful thermal features can change in an instant.
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