Geologists share data on Yellowstone’s July seismic activity in monthly update

GILLETTE, Wyo. — Geologists are on the hunt for the cause of the July 23 hydrothermal explosion at Yellowstone National Park, and new data reveals more about the area before and after the blast.

In a video posted to its X account, the park shared insight from U.S. Geological Survey Volcanoes geologist Mike Poland. Poland, the Yellowstone Volcano Observatory Scientist-in-Charge, explained that the blast at Black Diamond Pool in Biscuit Basin was a classic hydrothermal explosion.

Following the explosion, he explained, many of the rocks that had been sent skyward were later discovered to be coated in silica. A natural material, silica can build up in the underground channels of geothermal pools and backstop them, priming them for possible eruption.

“It’s an important reminder of Yellowstone’s dynamic and ever-changing nature,” Poland said. “Fortunately, no one was injured.”

The Biscuit Basin will remain closed while scientists evaluate the area and assess if the geothermal features are behaving any differently than before.

Despite the dramatic explosion at Black Diamond Pool, data showed that July was a calm month for seismic activity overall, Poland said. The incident came after a series of mild earthquakes in the northwest corner of Yellowstone, the strongest of which was 2.7 magnitude. In all, 64 earthquakes were recorded in July, a relatively low number.

While nobody was hurt in the Black Diamond Pool blast, not all of Yellowstone’s rumblings have had the same luck.

In the video, Poland also describes the Hebgen Lake Earthquake, a 7.3 magnitude earthquake that claimed the lives of 28 people in 1959. The 65th anniversary of the event, which created Yellowstone’s Quake Lake, is on Aug. 17.