Did you feel it?
A magnitude 4.3 earthquake struck Sunday evening at 7:21 p.m. PT about 35 miles northwest of Seattle, south of Port Townsend, according to preliminary reports from the USGS and the Pacific Northwest Seismic Network.
Many people reported feeling the shake, including in parts of Seattle.
A tsunami is not expected, according to the U.S. National Tsunami Warning Center.
ShakeAlert, an automated system designed to warn people that an earthquake has occurred and shaking is imminent, was reportedly not activated because the earthquake was below magnitude 4.5. ShakeAlert debuted in Washington state two years ago; it’s available in other West Coast areas.
The threat of a massive earthquake has simmered beneath the surface in the Pacific Northwest.
Seattle has two primary faults: The Seattle Fault that runs east-west through the middle of the city, capable of earthquakes up to 7.4 magnitude; and the Cascadia Subduction Zone along the coast, capable of a magnitude 9 earthquake.
The Cascadia Subduction Zone stretches more than 620 miles from the northern edge of Vancouver Island, B.C., to Cape Mendocino in Northern California. Along the fault, the tectonic plates beneath the ocean are shoving under or “subducting” beneath the North American continental plate. But the plates don’t slide smoothly and instead build up frictional stress that is released in a quake.
The National Science Foundation last month announced $15 million in new funding over five years for the creation of the Cascadia Region Earthquake Science Center (CRESCENT), which will research the Cascadia Subduction Zone. The scientists will study the fault to identify locations of increased strain and work to forecast potential impacts of an earthquake to better help communities prepare for an event.
The facility will be based at the University of Oregon and the University of Washington is a lead partner. It’s the first center in the U.S. focused on subduction quakes.
On Feb. 28, 2001, the Seattle area experienced the 6.8 magnitude Nisqually earthquake, which damaged buildings and roadways.
