CHEYENNE, Wyoming. — A surprise eruption that shot steam, water and dark-colored rock and soil hundreds of feet into the air on Tuesday sent people in Yellowstone National Park fleeing for safety.
The hydrothermal explosion occurred around 10 a.m. in Biscuit Basin, a collection of hot springs a few miles north of the famous Old Faithful Geyser.
Videos posted online showed a few dozen people watching from a boardwalk as the eruption spewed and grew before them. As water and debris fell, they ran to get out of the way, some shouting, “Back up!” and “Holy cow!” People turned to watch the scene beneath a huge plume of steam.
The eruption damaged the boardwalk, a raised wooden walkway that keeps people away from Yellowstone’s fragile and often dangerous geothermal areas. Photos and videos of the aftermath showed damaged guardrails and planks covered in rock and silt near mud holes.
No injuries were reported, but the Biscuit Basin area was closed for visitor safety, a statement from the U.S. Geological Survey said.
A hydrothermal explosion occurs when water suddenly steams underground. Such explosions are relatively common in Yellowstone.
Similar explosions occurred in Biscuit Basin in 2009, 1991 and after the 7.2 magnitude Hebgen Lake earthquake, 40 miles (64 kilometers) away, in 1959.
As dramatic as it was, it was still a minor event, according to the statement.
Scientists believe a series of hydrothermal explosions created Mary Bay on the northeastern side of Yellowstone Lake about 13,800 years ago. At 1.5 miles (2.4 kilometers) wide, Mary Bay is the largest known hydrothermal explosion crater in the world.
Yellowstone is centered on a massive, dormant volcano. The hydrothermal explosion did not signal new activity within the volcanic system, which remains at normal levels, the Geological Survey said.
___
Hanson reported from Helena, Montana.