Yellowstone National Park, which covers parts of Wyoming, Idaho and Montana, lies on top of a supervolcano that could effectively wipe out the United States if it were to explode. The last time it did, 640,000 years ago, it expelled 240 cubic miles (think about that) of rocky debris into the sky.
Early Thursday morning, residents of southern Montana feared the worst when a 5.8 magnitude earthquake shook the region. Though its epicenter was only 230 miles from Yellowstone, the United States Geological Survey (USGS) says the seismic activity was not irregular, and the supervolcano is not expected to erupt anytime soon.
"The location and focal mechanism solution of this earthquake are consistent with right-lateral faulting in association with faults of the Lewis and Clark line, a prominent zone of strike-slip, dip slip and oblique slip faulting trending east-southeast from northern Idaho to east of Helena, Montana, southeast of this earthquake," said the USGS.
Nevertheless, people were concerned.
The earthquake, which was the eighth largest ever recorded in Montana and largest in 34 years, comes just weeks after a flurry of smaller earthquakes hit the region. The swarm of activity began June 12, and by the end of the month nearly 900 earthquakes had been recorded near the Yellowstone supervolcano, along the western edge of the park.
Though the heightened seismic activity has stoked fears of a possible supervolcano eruption, Jacob Lowenstern of the USGS told Newsweek that it is not without precedent.
“The swarm in 2010 on the Madison Plateau lasted at least three weeks. In 1985, there was one that lasted several months,” he said. “Yellowstone has had dozens of these sorts of earthquake swarms in the last 150 years it's been visited. The last volcanic eruption within the caldera was 70,000 years ago. For magma to reach the surface, a new vent needs to be created, which requires a lot of intense geological activity.”
The USGS puts the odds of a volcanic eruption at 1 in 730,000. Even if an eruption were to occur, it would likely result in lava flow rather than a cataclysmic explosion. Though this would have an effect on Yellowstone, it would not bring about the end of the United States as we know it.
The 5.8 magnitude earthquake that hit Montana early Thursday morning may have knocked some dishes over and woke up a few residents, but the supervolcano made it through the night undisturbed.
More from Newsweek