Extreme heat from a massive supervolcano underneath Yellowstone National Park is melting a major roadway at the popular summertime tourist attraction. Park officials have closed the area to visitors.

Firehole Lake Drive, a 3-mile-plus offshoot of the park’s Grand Loop that connects the Old Faithful geyser and the Madison Junction, is currently off limits. Park operators say the danger of stepping on seemingly solid soil into severely hot water is “high.”

“It basically turned the asphalt into soup. It turned the gravel road into oatmeal,” Yellowstone spokesman Dan Hottle said.

The affected roadway offers access to the Great Fountain Geyser, White Dome Geyser, and Firehole Lake.

“There are plenty of other great places to see thermal features in the park,” park public affairs chief Al Nash told The Weather Channel. “I wouldn’t risk personal injury to see these during this temporary closure.”

While thermal activity under the park often gives way to temperature fluctuations that can soften asphalt throughout Yellowstone, Hottle said the latest wave seems worse than usual.

“But it’s hard to tell if a thermal area is hotter than normal, because it’s always fluctuating here,” he said, according to the Los Angeles Times. “Road closures are business as usual for us.”

 

Maintenance workers now must lift the melted asphalt from the roadway, then apply sand and lime to soak up any remains, according to Hottle.

The spokesman said he hopes the road will be reopened by next week, adding that he does not believe the activity will significantly curb visits to the park.

Yellowstone’s supervolcano last erupted about 640,000 years ago, according to US Geological Survey records.

Last December, geologists reported that the magma reservoir under the supervolcano is two-and-a-half times larger than previous estimates.

“That’s not to say it’s getting any bigger,” said analysis team scientist James Farrell of the University of Utah. “It’s just that our ability to see it is getting better.”

The supervolcano has the potential to spew more than 240 cubic miles (1,000 cubic kilometers) of magma across Montana, Idaho, and Wyoming.

“We believe it will erupt again someday, but we have no idea when,” Farrell told National Geographic.

In March, a viral video of bison stampeding through the park gave rise to rumors of an imminent eruption.

 

In early April, scientists and park officials debunked the fears, saying the bison run was a natural migratory occurrence, not a sign of impending volcanic activity. That very same week, a 4.8 magnitude earthquake shook the northwest section of the park, marking the largest seismic activity at Yellowstone since 1980.

The earthquake occurred near “an area or ground uplift tied to the upward movement of molten rock in the super-volcano, whose mouth, or caldera, is 50 miles long and 30 miles wide,” Reuters reported at the time.

The uplift does not make volcanic activity more likely, though, according to Peter Cervelli, associate director for science and technology at the US Geological Survey’s Volcano Science Center in California.

“The chance of that happening in our lifetimes is exceedingly insignificant,” he said.