CHEYENNE, Wyo. A surprise eruption that sent steam, water, rocks and dark-colored dirt hundreds of feet into the sky on Tuesday sent people running for safety in Yellowstone. National park.
The hydrothermal explosion happened around 10 a.m. in Biscuit Basin, a cluster of hot springs 2 miles north of the famous Old Faithful Geyser.
Video posted online showed a few dozen people watching from a boardwalk as the eruption spread and grew in front of them. As water and debris began to fall, they ran to stay away, some shouting “Back!” and “Damn!” People then turned to watch the spectacle under a huge cloud of steam.
The eruption damaged the boardwalk, an elevated 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 boards covered in rock and silt near muddy pools.
No injuries were reported, but the Biscuit Basin area was closed for the safety of visitors, according to a statement from the U.S. Geological Survey.
The explosion happened near Black Diamond Pool, a 37-meter-long hot pool that is the largest thermal feature in the basin.
A National Park Service aerial photo taken later showed the pool slightly enlarged near the boardwalk compared to recent satellite images and its water turned a muddy beige color. The deep Sapphire Pool, about 91 meters away, maintained its usual shades of blue.
A hydrothermal explosion happens when water suddenly turns to steam underground. Such explosions are relatively common in Yellowstone. Park geologists were investigating what specifically happened in this case.
Similar explosions happened in Biscuit Basin in 2009, 1991 and after the 7.2 magnitude earthquake at Lake Hebgen, 40 miles away, in 1959.
As dramatic as it was, the last one was small, according to the release.
Scientists theorize that a series of hydrothermal explosions created Mary Bay on the northeast side of Yellowstone Lake about 13,800 years ago. At 2.4 kilometers wide, Mary Bay is the largest known hydrothermal explosion crater in the world.
Yellowstone is centered on a huge dormant volcano. The hydrothermal explosion did not indicate new activity in the volcanic system, which remains at normal levels, according to the Geological Survey.
Although no one was injured, this is not always the case with Yellowstone’s thermal features.
It is known that at least 22 people he died of injuries related to thermal features in and around the 3,471-square-mile (9,000-square-kilometer) national park since 1890.
Visitors are warned to stay on the boardwalks and trails in the thermal areas, where some pools and springs have a thin, brittle crust that covers the scalding and sometimes acidic water.
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Hanson reported from Helena, Montana.
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