YELLOWSTONE NATIONAL PARK, July 24, 2024 (Gephardt Daily) — After Tuesday’s hydrothermal explosion, officials have closed the site of the blast in Yellowstone for the year because of the possibility of more, but smaller, explosions.
“The explosion, which sent steam and debris to a height of hundreds of feet above the ground, destroyed a nearby boardwalk and ejected grapefruit-sized rocks tens to hundreds of feet from the source,” the NPS said in an update online Wednesday night about the July 23 eruption in Biscuit Basin.
“Some blocks closest to the explosion site are about 3 feet (1 meter) wide and weigh hundreds of pounds. The explosion was largely directed to the northeast toward the Firehole River, and the largest blocks of debris fell in that direction.
“The dark color of the explosion was a result of mud and debris mixed with steam and boiling water. Although visitors were present at the time of the event, no injuries were reported.”
The blast resulted from water suddenly transitioning to steam in the shallow hydrothermal system beneath Black Diamond Pool and was not caused by volcanic activity, the NPS said.
“Given the recent changes to the hydrothermal plumbing system, small explosions of boiling water from this area in Biscuit Basin continue to be possible over the coming days to months.
“USGS and NPS geologists will be monitoring conditions, mapping the debris field, and sampling water to assess any changes in the shallow hydrothermal system over the next several days.”
Hydrothermal explosions typically occur in the park one to a few times per year, the NPS said, but often in the back country where they may not be immediately detected.
The changes NPS referred to include alterations to the shape of Black Diamond Pool and impacts to nearby Black Opal Pool in Biscuit Basin. Both pools are murky due to debris, and the unstable ground around their edges occasionally slides into the water.
“Just after the eruption, Black Diamond Pool exhibited minor roiling and water spouting.
“The water level in the pool rose over the course of the day, and by Tuesday afternoon the roiling transitioned to occasional bursts of hot water that reached about 8 feet (2.4 meters) in height.”
By Wednesday morning the water bursts had stopped, the NPS said, but both pools were overflowing.
The agency also shared some of the history of hydrothermal explosions at Yellowstone.
Similar, although smaller, hydrothermal explosions took place in 1989 at Porkchop Geyser in Norris Geyser Basin, and on April 15, 2024, from the Porcelain Terrace Area of Norris Geyser Basin. A small hydrothermal explosion occurred from Wall Pool, in Biscuit Basin, in 2009.
Significant hydrothermal explosions, probably similar in size to that of July 23, 2024, occurred in the 1880s at Excelsior Geyser, in Midway Geyser Basin.
