Yellowstone rattled by swarm of more than 140 earthquakes in past day, geologists say

by MADDIE CAPRON
| July 20, 2021 7:00 AM

Maddie Capron Idaho Statesman (TNS)

A swarm of more than 141 earthquakes is rattling Yellowstone National Park, geologists said.

The U.S. Geological Survey said Friday that an ongoing earthquake swarm that began at 5:52 p.m. Thursday is centered beneath Yellowstone Lake. There have been 40 earthquakes bigger than a magnitude 2, and two have been above a 3.0 magnitude, USGS said.

In the past day, there have been 10 earthquakes with a 2.5 magnitude or greater, according to USGS. The largest was a 3.1-magnitude quake that shook beneath Yellowstone Lake at 8:12 a.m. Mountain Time.

The earthquake swarm is nothing to worry about, geologists said.

"Earthquake sequences like these are common and account for roughly 50% of the total seismicity in the Yellowstone region," USGS said on Twitter. "This swarm is similar to one that occurred in about the same place during December 2020."

Some people, however, still worry earthquakes in Yellowstone are a sign that the "supervolcano" that lies beneath the park will soon erupt, which could have regional and global consequences.

"Such a giant eruption would have regional effects such as falling ash and short-term (years to decades) changes to global climate," USGS said on its website. "Those parts of the surrounding states of Montana, Idaho, and Wyoming that are closest to Yellowstone would be affected by pyroclastic flows, while other places in the United States would be impacted by falling ash (the amount of ash would decrease with distance from the eruption site)."

The USGS doesn't think an eruption at Yellowstone is likely for thousands of years. Even with the current swarm, the alert level at the Yellowstone Volcano Observatory is green, which is normal.

Earthquakes in Yellowstone typically happen in swarms, according to the park. Swarms happen in many places where there is volcanic activity and occur for a number of reasons. The most common is when water gets into faults in the Earth's crust, according to USGS.