Crater Lake has its first reported earthquake since 2015

Crater Lake has its first reported earthquake since 2015 (Courtesy Crater Lake National Park)

Scientists are excited about the ground rumblings at Crater Lake National Park but it's more academic than any threat to the public.

On June 9, at approximately 1800 UTC (11 a.m. Pacific) an M 1.3 earthquake occurred under Crater Lake at a depth approximately 2 km below sea level.

"You're looking at three or four miles down from the surface," Seismologist Wes Thelen said.

The event was followed by around two dozen aftershocks over the next 12 hours. Scientists at the U.S. Geological Survey's Cascade Volcano Observatory in Vancouver, Washington poured over the spectrogram and the readings from the four seismometers in the caldera including one on Wizard Island.

Thelen said the initial earthquake was near the southeast rim of Crater Lake near the Dutton Cliff. He also said that though it doesn't happen often, it doesn't mean that the volcano can't experience earthquakes.

"We don't see a lot of earthquakes here," Thelen said. "This is more or less normal for the volcano to have earthquakes."

The last mention of a series of aftershocks to an earthquake, or a swarm, was May 2015 with four volcano tectonic earthquakes. Most VT earthquakes are not tied to the movement of magma in the volcano but rather a response from a weak fault moving in the area.

Prior to that, in April 2014 there were around 20 VT earthquakes, with four located about the same depth and location. Historically, there were others in 1994 and 1920.

While Crater Lake is an active volcano, it's been 4,800 years since the old Mount Mazama blew up. Thelen said he doesn't think it's going to erupt anytime soon.

Volcano Observatory also noted that although Crater Lake is an active volcano, there is no current danger.

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