'Micro earthquake' shakes Amboy-area residents

Magnitude 2.7 jolt not related to Mount St. Helens system

By Tom Vogt, Columbian science, military & history reporter

Published:

Updated: October 19, 2011, 5:49 PM

 

A magnitude 2.7 earthquake shook the Amboy area at 12:51 p.m. Wednesday.

The Pacific Northwest Seismic Network described the event as “a micro earthquake” that occurred at a depth of about 7 miles.

It was centered about 3 miles northeast of Amboy and 4 miles north of Yacolt.

“It was felt by a number of people in the Amboy area,” said Bill Steele, spokesman for the Pacific Northwest Seismic Network.

In addition to operating a seismograph network in Washington and Oregon, the Seattle-based center also has a “Did you feel it?” link on its website (http://www.pnsn.org/welcome.html).

“About 25 people have been online filling out a ‘felt’ report,” Steele said late Wednesday afternoon. Responders described it as between weak and light, “but they still definitely noticed it.”

The quake occurred in an area of tectonic weakness, Steele said, but he made sure to add: “It was not related to the Mount St. Helens system.”

Areas of stress off the Pacific Coast get a lot of blame for regional jolts, but Wednesday’s quake 22 miles north-northeast of Vancouver was more likely a result of geologic forces in California, Steele said.

“Yosemite is moving north at 11 millimeters a year, and there is quite a bit of north-south compression.”

Whatever the cause, Steele said, “This is always a good reminder to check your family’s plan, to make sure you have food and water to last a week.”