Hadley Bodell
YELLOWSTONE, Wyoming (KIFI) – A new crater has made its debut in Yellowstone National Park, filled with near-boiling water and caused by pressure changes just below the surface in Biscuit Basin. Monitors alerted scientists of seismic activity north of the Black Diamond Pool while park service employees saw milky water in the Firehole River downstream.
Upon checking the camera footage, geologists saw steam erupting from the ground.
The new hydrothermal pool that formed north of the Black Diamond Pool in Biscuit Basin, Yellowstone, USGS 2026
Learning from the Past
In 2024, Black Diamond Pool erupted in a historic hydrothermal event, ruining boardwalks nearby and causing the closure of Biscuit Basin. Following that explosion, scientists installed cameras and new monitoring systems including an infrasound array, which tracks low frequency acoustic energy – the kind seen from explosions. They also set up microphones that allow them to determine the direction the sound is coming from.
Black Diamond Pool has remained active with interesting spouts of energy, including eruptions of various sizes and changes in the water level associated with acoustic energy and seismic activity. It turns out, the cameras were in just the right place.
Catching an Explosion
Just after 5 a.m. on June 13, alarms on the monitoring systems blared, indicating seismic events in the basin area. Geophysicist and lead scientist with the Yellowstone Volcano Observatory Michael Poland said they determined the activity was located north of the Black Diamond Pool.
Reports began to come in from park service employees of milky waters in the Firehole River downstream. Several miles away, there was evidence of an eruption at Biscuit Basin.
Milky waters in the Firehole River downstream from Biscuit Basin, Yellowstone, June 13 USGS
“We could see [on the cameras] there was clearly some steam jetting,” Poland said. “When geologists went out there to take a look, they found rocks had been thrown out. There were a couple of big cracks that are full of boiling water that had formed.”
One of the crack vents that formed was over 60 feet long. Poland called the event a “smallish hydrothermal explosion, but still impressive.” This explosion also proves the importance of monitoring data, because without it, the new pool and eruptive activity may have gone unnoticed in the already-closed area.
Fissures seen in the Biscuit Basin area following the event, Yellowstone, June 13 USGS
Between June 14 and 16, a 21-foot-wide crater formed in Biscuit Basin. Ground that geologists had walked on days prior was now caved in and covered with boiling water.
“The ground was really thin and it fell into an area that was probably growing a slightly subterranean pool,” Poland said. “Then, on June 18, we started seeing that pool go through periods where it was spouting almost like a geyser.”
Every few moments, the new pool would spout a plume of boiling water and steam into the air. Then, on June 23, scientists observed an eruption of the pool.
“It sent things up many tens of feet, just a single one-off event,” Poland said. “But, clearly the area is still evolving and is pretty dynamic.”
An “Exciting Opportunity” for Scientists
The exciting part about the newly formed pool and surrounding vents is their unexpected activity and unpredictability. Poland said they don’t have current records of this kind of event happening in a place where it’s easy to observe. Many modern hydrothermal explosions happen in the backcountry or over the winter season, where changes in geography or activity are found later.
“This particular event is a really important scientific opportunity because it happened in an area that was already closed, so it definitely doesn’t pose a hazard to the public and in an area that’s really well-monitored,” Poland said. “We can track the evolution of the features visually by going out and looking at them, but also by the monitoring data we have.”
By understanding the progression that hydrothermal explosions can go through, scientists can determine the hazard to other thermal areas in the park. Poland said Biscuit Basin is known for having explosive character, with many past events.
“It seems to have a lot of boiling water that’s right at the interface between liquid and steam, and that’s a recipe for explosions because if you increase the pressure a little bit, you raise the water above the boiling point,” he said. When the pressure releases through cracks or vents, the water instantly flashes to steam and causes an explosion.
Updated map of the Biscuit Basin area including the new pool and vent system, Yellowstone, USGS 2026
It’s more unique that a new pool formed in relation to this seismic activity. Poland said another pool formed in 2024 near the Norris Geyser Basin where flat ground collapsed.
With seismic and infrasound monitoring stations, Yellowstone scientists are opening the door to a new way of exploring the park’s thermal areas.
“It’s an opportunity to study this kind of event and then hopefully apply what we learned to other places,” Poland said. “There may have been precursors. That’s one of our goals to understand whether or not we can detect the likelihood that this might happen in the future in a certain place. We’ve never had monitoring instrumentation this close to a hydrothermal explosion.”
Poland added that geologists will likely spend the next several months to years pouring over the data collected prior to this explosion north of the Black Diamond Pool. If they are able to find warning indications prior to the event, it would open up a whole new world for forecasting explosions.
Hydrothermal explosions have caused many injuries and fatalities around the world, with volcano warning systems becoming one of the first to save countless lives in natural disasters. Now, geologists have the opportunity to study whether or not there were signals in the Biscuit Basin area before this explosion.
“If we could develop some means of anticipating them, then that could have real impact in parks, in thermal areas around the world, not just in Yellowstone,” Poland said.
Impact of Explosion
A common misconception is that one eruption must affect all other geographical sites in the area. Poland said this mini-explosion was local and didn’t effect any other features in Biscuit Basin. Scientists watched Black Diamond Pool, just a few hundred feet from the seismic area including the new pool, and didn’t see any changes.
“It doesn’t always mean something big is going to happen,” Poland explained. “If you have a leaky faucet in your house, that doesn’t mean your neighbor has a leaky faucet now. If everyone on your block has a leaky faucet, maybe there’s a bigger issue. In the case of Biscuit Basin, it’s one leaky faucet and it’s because something is wrong with it. All the others are fine.”
Individual features in Yellowstone have their own events often, but if they begin to see further activity across the basin, it could indicate a larger seismic event.
There is also potential the new pool becomes a consistent geyser, but Poland says it’s more likely it has activity for a short period of time and then calms.
“It’s possible this new feature will have it’s moment and then go quiet, but it’s also possible it will develop into another geyser,” he said. “That’s part of the excitement of Yellowstone, it’s so dynamic. Every time you go, it’s different.”
What happens next?
Poland said geologists are allowed to enter and explore the basin area, while it remains closed to the public.
“They’re documenting the changes they’re seeing, looking at the temperature of the water, the chemical composition of the water to see whether it’s cooling off or heating up,” he said. “Documenting the sizes of the features like the pool has a rim that kind of slopes away underneath it so it’s going to get bigger over time.”
They’ll track other openings and vents that monitor cameras may have not picked up and line it up with the seismic data to begin discovering whether these explosions may be predictable.
Yellowstone National Park hoped to re-open the Biscuit Basin area to the public, but with this recent explosion, it has proven too hazardous for visitors. It will remain closed while scientists explore the event.
This was Not a 2024 Repeat
When news broke of another eruption near the Black Diamond Pool, it was easy to equate it to the eruption in June of 2024. Poland says their scale is drastically different.
“The event that occured on June 13 threw rocks, but only a few tens of feet and they tended to be overall smaller,” he said. “It was smaller in terms of the energy released, and also not in the middle of a pool. It happened in an area that was previously dry and barren, and happened over a much broader area.”
The 2024 explosion happened right in the middle of the Black Diamond Pool, meaning geologists can’t see what the vent area looks like because it’s underwater. Now, they have the unique opportunity to see the effected area north of that pool from this explosion.
“Different styles, definitely, but the same underlying cause which is these pressure fluctuations that allow water to flash to steam,” Poland said.
If you’re interested in following along on the geologist’s journey to finding new information about these eruptions and seismic activity in Yellowstone, the Yellowstone Volcano Observatory posts a weekly series called the Caldera Chronicles. To see videos and read more information, visit their website at https://www.usgs.gov/observatories/yvo.
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