Yellowstone hydrothermal explosion: ‘We were terrified’

The woman who shot a video of a hydrothermal explosion in Yellowstone National Park on Tuesday morning told WyoFile she and her family were terrified as the blast sent boiling water and rocks skyward, destroying parts of a boardwalk, its guardrail and a nearby bench.

The explosion at about 10 a.m. in Biscuit Basin about 2 miles northwest of Old Faithful Geyser sent steam about 100 feet into the air and launched rocks — at least one appearing to be bigger than a basketball — and debris across an area perhaps 50 yards in diameter.

“It just exploded in seconds, with rock and debris flying,” said Vlada March, a real estate agent from California whose video of the eruption went viral on social media.

She spoke on her cell phone while still in Yellowstone. Park officials said they had received no reports of injuries.

“Of course, we were terrified,” March said.  “My mother got covered. It was insane.”

Five people were in her party, March said, and the group was traveling with a guide.

“He told us to run.”

Her video shows the eruption ejecting rocks and mud while people dash away along a park boardwalk as debris rain down.

Photographs released by Yellowstone show damage to the boardwalk’s 2×6-inch wooden planking, a guardrail and bench. One photograph shows a rock slightly larger than a basketball that crashed through the boardwalk. It landed several yards from what appears in photographs to be the mud filled eruption crater about 20 feet wide and 60 feet long.

Steam wafted away shortly after the event, leaving a field of mud, gravel and rocks.

“It cleared within a minute,” March said.

Officials closed the area, including the Biscuit Basin parking lot. Other parts of the park, and the Grand Loop road which runs near the site of the explosion, remain open.

The explosion occurred near Black Diamond Pool, the park said in a joint statement issued with the U.S. Geological Survey.

A sign on the boardwalk guardrail in one Yellowstone photograph suggests the event happened across the walkway from Black Opal Spring.

“Today’s explosion does not reflect activity within [the] volcanic system, which remains at normal background levels of activity,” the USGS said in a statement. “Hydrothermal explosions like that of today are not a sign of impending volcanic eruptions, and they are not caused by magma rising towards the surface.”

Magma movements would cause “vastly different styles of activity — earthquakes galore and ground deformations,” said Michael Poland, scientist in charge of the Yellowstone Volcano Observatory.

Hydrothermal explosions occur when water flashes to steam underground because of changes in subterranean plumbing.

“This kind of thing happens once or twice a year in Yellowstone, often in the backcountry or when nobody’s around to see it,” Poland said.

Porkchop Geyser exploded in the Norris Geyser Basin in 1989 and monitoring equipment detected another event there in April of this year. An explosion similar to the most recent event occurred in Biscuit Basin in 2009 and traces of other unseen events have been observed over the years across the park.

The event left March shaken, she said. But she continued her family’s tour.

“It’s beautiful,” she said of Yellowstone.

This story was updated to include the Google Earth screenshot — Ed.