Mount Rainier caps swarm of weekend seismicity with 3.6 magnitude quake

After a spurt of seismic activity this weekend, Mount Rainier National Park was shaken by a 3.6 magnitude earthquake Sunday afternoon.

The quake hit at 12:31 p.m. and was felt as far as Kent, nearly 80 miles away, the U.S. Geological Survey reported. The relatively shallow quake was centered roughly a mile beneath the Earth’s surface.

The nearest town is Packwood, population 230, 13 miles northwest of the epicenter.

Since Thanksgiving Day, more than a dozen other smaller quakes have shaken Mount Rainier. The largest, until Sunday’s, was a magnitude 1.0.

The mountain generally sees something in the neighborhood of a quake a week. But seismologists said the weekend tremors weren’t anything out of the ordinary for the earthquake-prone volcano. In other words: No eruption is imminent from the nation’s third-most dangerous volcano.

“These periodic swarms of little earthquakes are quite normal for Mount Rainier,” said Bill Steele of the Pacific Northwest Seismic Network.

Regardless, people living near Mount Rainier should prepare for what might happen in the event of an eruption, said Wes Thelen, a research seismologist at the Cascade Volcano Observatory. Specifically, an eruption could cause lahars – large volcanic mudflows – to rip down the side of the mountain.

This quake, though, “does not change the lahar hazard at all,” Thelen said.