More earthquakes possible as swarm continues along Seattle fault
May 11, 2017, 2:20 PM | Updated: 4:49 pm
About 40 tremors have been recorded in the last week. (KIRO 7)
(KIRO 7)
A 3.6-magnitude earthquake was the largest so far in a swarm of quakes running along the Seattle fault near Bremerton over the past week.
The quake was reported at 12:35 a.m. Thursday. There have been at least 18 quakes in that area in the last 24 hours.
RELATED: Magnitude 3.4 quake shakes area west of Seattle
Thursday morning’s 3.6 earthquake east of Bremerton was nearly twice as strong as Wednesday’s 3.4 quake in the same area. Since midnight, there were six more quakes in Kitsap County.
About 40 tremors have been recorded in the area in the past week.
Swarm along Seattle fault
It’s important to understand that the earthquakes have occurred along the Seattle fault — from the Sammamish area, through Bellevue, South Seattle, under Puget Sound to Bremerton. So movement at one end could influence other portions of the fault. Given the location and frequency, the swarm has the region’s seismologists playing close attention.
John Vidale with the Pacific Northwest Seismic Network says the swarm is localized. However, ongoing quakes can sometimes indicate a larger event.
“Our worst fear is an earthquake on the Seattle fault,” Vidale said. “If the Seattle fault breaks on a 7, breaks right under the southern edge of the city, close to tall buildings and old buildings, that would be the worst case for the city of Seattle.”
The seismic network’s blog offered some explanation of the swarm Thursday morning, and noted that more quakes could occur.
We are having a nice vigorous swarm deep below the Seattle Fault Zone. The focal mechanism of the bigger events are consistent with North-South contraction. But we don’t really understand what causes these swarms. It is possible that more, and bigger, earthquakes (will) happen. It is also possible that this area quiets down again.
Even though the magnitude-3.6 quake happened east of Bremerton, people on Facebook said they felt shaking in Ballard, Issaquah and Edmonds.
If you felt it, file a report here.
As of 4:30 a.m. Thursday, 663 people reported feeling the 3.6 quake to the USGS.
MyNorthwest.com’s Dyer Oxley contributed to this story
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