Should we worry about recent Washington earthquakes? Expert explains

A series of earthquakes has rattled the Pacific Northwest in recent weeks, raising concerns and questions among residents. But should we be worried?

The latest tremor, a magnitude 3.9 quake, struck near Port Angeles on Wednesday, following a magnitude 4.5 quake near Orcas Island on Monday. These events are part of a noticeable uptick in seismic activity in the region.

Harold Tobin, Director of the Pacific Northwest Seismic Network and a professor at the University of Washington, said that while the increase in earthquakes is noticeable, it is not necessarily a cause for alarm.

“I would say the same thing as I said last week or early this week. Don’t worry about it,” Tobin told Charlie Harger, host of “Seattle’s Morning News” on KIRO Newsradio.

He acknowledged that the region has experienced about four noticeably felt earthquakes in the past couple of weeks, which is an uptick but still within the normal range of seismic activity for the area.

Are these earthquakes related?

Tobin explained that, in a broad sense, these earthquakes are all connected due to the tectonic activity in the region.

“We sit at this place where two of these giant tectonic plates grind against each other in the Earth’s crust,” he said. “In the smaller picture… they are quite different types of earthquakes,” Tobin noted.

Residents have been actively reporting their experiences with the recent quakes. The 4.5 magnitude quake near Orcas Island generated over 10,000 felt reports, while the more recent 3.9 magnitude quake, which was deeper, resulted in fewer reports.

“Different experience for people,” Tobin said, highlighting the variability in how earthquakes are felt depending on their depth and location.

The ShakeAlert app, designed to provide early warnings for significant earthquakes, was triggered by the Orcas Island quake but not by the smaller, more recent tremor.

“For the Orcas Island quake, it did trigger the apps that alert at the 4.5 level,” Tobin explained.

The system correctly determined that the quake did not meet the threshold for a full broadcast alert, which is set at magnitude 5.

What about the “Big One?”

Looking ahead, Tobin addressed the looming question of the “Big One,” a massive earthquake that could strike the region at any time.

“We are 325 years since the last one. We know that the average time between those from geological studies is about 450 to 500 years, but with quite a range,” he said.

While the exact timing is unpredictable, Tobin emphasized the importance of preparedness.

In the shorter term, Tobin suggested that the region is more likely to experience a significant but less catastrophic quake, like the 2001 Nisqually earthquake.

“That’s very strong shaking that will really cause significant damage potentially and could cause injuries,” he said.

The Nisqually quake, which had a magnitude of 6.8, caused extensive damage but fortunately resulted in no fatalities.

Related from MyNorthwest: 4.5 earthquake strikes off Orcas Island

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