More than 100 earthquakes strike near Oregon volcano in a single day, geologists say

More than 100 earthquakes shook near an Oregon volcano in one day, the U.S. Geological Survey said.

An area south of Mount Hood near Portland was hit by a swarm starting at noon Sunday, USGS said.

“An earthquake swarm at Mount Hood is ongoing,” USGS said on Facebook. “The earthquakes are associated with regional faulting and are not a sign of changes in volcanic activity.”

The quakes did not cause any damage, and they are not a sign of impending volcanic activity, USGS said. Many of the earthquakes were small in size.

Several earthquakes shook with a maximum magnitude of 2.7 and depths of about 3 miles below sea level, according to USGS.

Magnitude measures the energy released at the source of the earthquake, the U.S. Geological Survey says. It replaces the old Richter scale.

Quakes between 2.5 and 5.4 magnitude are often felt but rarely cause much damage, according to Michigan Tech.

“Swarms at Mount Hood are common and account for most of the seismicity at the volcano,” USGS said. “They can last hours to days.”

The area has seen other earthquake swarms in 2009, 2012, 2014 and 2020, geologists said.

Mount Hood is Oregon’s highest peak. It’s erupted “episodically” for 500,000 years and has seen two major eruptions during the past 1,500 years, USGS said.

This story was originally published January 18, 2021 at 6:36 AM with the headline "More than 100 earthquakes strike near Oregon volcano in a single day, geologists say."