Tourists sent running for their lives as hot spring explodes at Yellowstone

Footage has revealed the moment a hydrothermal explosion took place in Yellowstone National Park, sending tourists sprinting to get away.

Yesterday (23 July) at around 10:19am, an explosion occurred near Sapphire Pool in Biscuit Basin in Yellowstone National Park, Wyoming, US.

Visitors of the park were sent fleeing 'for their lives' and one tourist has since opened up about the terrifying experience.

What is a hydrothermal explosion?

Yellowstone Volcano Observatory explains via USGS that a hydrothermal explosion is a 'violent and dramatic event' which results in 'the rapid ejection of boiling water, steam, mud and rock fragments' reaching heights of 'two km (1.2 miles)'.

The explosion ejects material - mostly in the form of angular rocks cemented by clay called breccia - as 'far as 3-4km (1.8 to 2.5 miles)' and can leave craters that are 'from a few meters (tens of feet) up to more than two km (1.2 mi) in diameter'.

Hydrothermal explosions occur where 'shallow interconnected reservoirs of fluids with temperatures at or near the boiling point underlie thermal fields'.

"These fluids can rapidly transition to steam if the pressure suddenly drops. Since vapor molecules take up much more space than liquid molecules, the transition to steam results in significant expansion and blows apart surrounding rocks and ejects debris."

The observatory continues: "Hydrothermal explosions are a potentially significant local hazard and can damage or even destroy thermal features."

Large hydrothermal explosions are reported as occurring 'on average every 700 years' and while the explosion at Yellowstone yesterday was considered on the smaller side, it doesn't make it any less terrifying to see - and if the footage is an example of a small explosion, I dread to think what a big one looks like.

Tourists' experience of the explosion

A visitor of the park that morning named Vlada March - who was at the park with her two children, husband and grandma - told KTLA 5: "Everything was just fine, the water was blue and calm when we walked past it and within seconds, it became a huge explosion."

She also took to Facebook to share footage of the explosion, alongside the caption: "@Biscuit basin at Yellowstone national park Wyoming just exploded right in front of us. Boardwalk destroyed, my mom got some of the debris but everyone is safe.

"Unbelievable and grateful to be alive."

Temporary closure of the area

Yellowstone National Park Service has since 'temporarily closed' the area of Biscuit Basin as a result of the explosion.

It's website states: "The parking lot and boardwalks at Biscuit Basin, located north of Old Faithful, are temporarily closed due to a hydrothermal explosion that occurred July 23. Park staff will reopen the area once deemed safe.

"The Grand Loop Road remains open."

On its site, it adds that 'conditions' will be monitored both by park staff and staff from USGS and 'no other monitoring data show changes in the Yellowstone region'.

"Today’s explosion does not reflect a change in the volcanic system, which remains at normal background levels of activity," it continued. "This is an evolving incident, and additional details will be shared as more facts are known."

UNILAD has contacted Yellowstone National Park Service for comment.