Earthquake Swarm Strikes Tonasket Area

There's definitely a lot of things shakin' around the town of Tonasket these days.

According to the U.S. Geological Survey (USGS), the small community of roughly 1,100 residents in Northern Okanogan County has been the site of 39 small earthquakes since Sunday (April 13), including three in excess of magnitude 3.0 on the Richter Scale.

The largest of the temblors was a magnitude 3.2 that happened on Monday (April 14) at 4:01 a.m., and was preceded by a magnitude 3.1 quake at 6:46 p.m. on Sunday, while another magnitude 3.1 also hit on Wednesday (April 16) at 7:23 a.m.

The remainder of the quakes have all been between a magnitude 1.1 and 2.8, and each of the tremors have happened within five miles to the west of the town at a depth of 9-10 miles.

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Seismologist Erin Wirth with the USGS office in Seattle says while earthquake swarms of this variety aren't unusual to see in Washington State, they don't often occur in this area.

"We live in a very seismically-active region here in Washington State, so earthquakes are not uncommon. I wouldn't say this is particularly out of the ordinary but swarms in this part of the state aren't necessarily very common either. Our detection capabilities have improved over the past five to ten years, so it doesn't mean they weren't happening in the past, it's possible that we just weren't recognizing them."

Wirth says although it might seem like something bigger is brewing under the Earth's surface in the rural community, it's likely the quakes will continue to be small in size before eventually subsiding.

"Right now, these earthquakes are behaving like a swarm. That means the quakes that are happening kind of look a lot like each another and there's not necessarily going to be a larger event in the future. What I think we can expect to see is probably just more of these smaller magnitude quakes happening in this region over the next few days or weeks potentially."

Wirth adds that while the likelihood of a larger earthquake isn't high, residents and visitors should still be well prepared in the event something bigger does rumble through the region.

On social media, dozens of people in the vicinity of Tonasket, Loomis, and Ellisforde have reported feeling the three larger temblors .

Wirth says the earthquakes are not associated with any known faults in the region but are likely not being caused by anything other than geologic activity.

The largest known earthquake to strike the region happened about 90 miles to the south on Dec. 14, 1872, when what scientists estimate was a magnitude 7.2 quake hit near the area of what is modern-day Entiat.