A 4.2 magnitude earthquake just south of Bremerton rattled homes in parts of Thurston County Tuesday afternoon.
The seismic event started at 2:05 p.m. on Tuesday, Sept. 29, nearly 12 miles south-southwest of Bremerton and about 17.32 miles below the surface, with the epicenter near Wauna.
The last tremors dissipated shortly after 2:10 p.m., according to information from the Pacific Northwest Seismic Network.
The Pacific Northwest Seismic Network described the earthquake’s depth as “fairly deep for a crustal earthquake,” but noted that “Earthquakes at this depth in this area are not uncommon.”
While noticeable, the magnitude was low enough to be considered a “light” earthquake, meaning it caused minor shaking and little to no structural damage.
The earthquake’s intensity ranked a three on the Modified Mercalli Intensity Scale for earthquake intensity — meaning it was felt most by people indoors, especially on the upper floors of buildings, with vibrations similar to a truck passing by.
Some people in and around Seattle, Tacoma, Bremerton and Olympia reported feeling a sudden jolt, others felt a soft rumble, and some reported feeling nothing at all.
Thurston County Emergency Management confirmed at about 2:20 p.m. Tuesday afternoon that it was aware of the earthquake felt in parts of Thurston County a few minutes prior.
“It’s a good reminder that we live in earthquake country and need to be prepared!,” the department stated in a social media post, urging residents to “take a few minutes to review your emergency plans, check your emergency supplies, and make sure you know what to do when the ground starts shaking.”
The U.S. Geological Survey anticipates that there’s a small chance for another moderate-magnitude earthquake in the area within the next week. The agency’s aftershock forecast shows a 5% chance for another magnitude-4 or higher earthquake in the area within the next day, and a 8% chance for one within the next week.
The chance for a small-magnitude earthquake within the next week is higher, with the agency forecasting a 27% chance for a magnitude-3 or higher earthquake within the next day, and a 39% chance for one within the next week.
Earthquakes below a magnitude of 2.5 are rarely felt by humans.
