PORT ANGELES — A swarm of earthquakes reported as peppering the Puget Sound region over the past few days was punctuated by a low-key 3.4-magnitude underwater temblor late Thursday morning northeast of the North Olympic Peninsula off Whidbey Island.
The quake near Whidbey Island was noticed by at least 50 residents of Clallam and Jefferson counties, according to the Pacific Northwest Seismic Network.
Among the closest points in Clallam and Jefferson counties was Port Ludlow in Jefferson County, 9.3 miles southwest of the epicenter, according to the Seismic Network, which is co-sponsored by the U.S. Geological Service and operated by the University of Washington and University of Oregon.
The Seismic Network reported the earthquake’s depth at 14.7 miles, location as 3.7 miles southeast of Freeland off Whidbey Island. The time of the event was 10:56 a.m. Thursday.
“It felt like a large jolt, like something maybe had hit the wall,” Tanya Cray, administrative assistant for Port Ludlow Fire District 3, said Thursday. “I didn’t know if something in the building may have fallen down.”
She was not among the 50 people from Clallam and Jefferson counties who had responded to the “Did You Feel It?”interactive function on the network’s website at pnsn.org, including 22 from Port Ludlow, 12 from Port Angeles and nine from Port Townsend.
Nothing fell or shook at the Port Ludlow Fire Station, Cray said.
“I looked up in the other office to see if anyone else had noticed it, and no one looked back at me. They felt the same as I did, nothing earth-shattering, obviously,” she said.
Cray’s husband, Jared, did not feel anything from 3 miles away.
The quake was rated “minor” by the Emergency and Disaster Information Service, operated by the National Association of Radio Distress-Signalling and Infocommunications.
It was preceded by a series of temblors in the magnitude 3.3-3.5 range from last week through Wednesday, said Renate Hartog of the Seismic Network on the website’s blog.
“Rather than call it a mainshock-aftershock pattern, we can now call it a swarm, which basically means a cluster of earthquakes close in space and time that doesn’t have an obvious mainshock,” Hartog said.
“Swarms of small earthquakes are not unusual in our region,” she added. “However, this swarm is interesting in that it might be related to the Seattle Fault Zone.”
The zone, which runs through downtown Seattle, has the potential for a magnitude 6 earthquake, Hartog said.
“If geologic studies now in progress sustain our current view of Seattle Fault Zone hazards, it is likely that the greater Seattle area will see upward revisions in building codes,” the USGS said on its website.
The Seattle fault is not related to the Cascadia Subduction Zone, which is a separate 620-mile megathrust fault with catastrophic earthquake potential that stretches from northern Vancouver Island to Cape Mendocino, Calif.
It lies about 50 miles off the coast of Washington, according to the Seismic Network.
The fault separates the Juan de Fuca and North America plates, with seismic movement created by the Juan de Fuca plate moving toward, and beneath, the continent, or the North American plate.
There were no emergency calls to Peninsula Communications from Clallam County residents that were related to the temblor as of about 1:30 p.m. Thursday, said Mary Rife of emergency dispatch service.
Rife said a reporter’s inquiry was the first she heard of the earthquake.
The same was true for Clallam County Sheriff Bill Benedict, he said.
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Senior Staff Writer Paul Gottlieb can be reached at 360-452-2345, ext. 55650, or at pgottlieb@ peninsuladailynews.com.
