Hydrothermal Explosion in Yellowstone's Biscuit Basin (July 23, 2024)

What just happened at Biscuit Basin in Yellowstone National Park? Kaboom! Visitors witnessed a towering plume of steam, rock and mud rise several hundred feet into the air. The brief July 23 event was a classic example of a hydrothermal explosion, not a volcanic eruption. And with all the hot water circulating in the subsurface of this active volcano, it’s no surprise that hydrothermal explosions are Yellowstone’s most common geologic hazard. Yellowstone's hydrothermal (hot water) system is powered by a cooling magma reservoir several miles beneath the surface. Even though the presence of hot water near the surface is partially due to that magma, this explosion was not triggered by changes in the magmatic system, like magma interacting with groundwater to cause it to convert to steam. 

Rather, the event was rooted in the very shallow hydrothermal system, where transitions between liquid water and steam are common and can occur when silica (dissolved in the water) clogs hot water conduits, causing changes in pressure that may lead to explosions.

Mike Poland, scientist-in-charge of the Yellowstone Volcano Observatory, talks about this previously underappreciated hazard and how it recently gained a little more respect

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