Hundreds of tiny earthquakes have rumbled through the Bremerton area since the start of May 2017.
How long the shaking will continue is anyone’s guess. Days, months, years, or until the next BIG ONE along the Cascadia?
Seismologists hope the ongoing earthquake swarm, centered between East Bremerton and Bainbridge Island, will reveal new information about the orientation of fault lines running beneath central Puget Sound. Because everything is almost unknown!
The quakes have already offered some intriguing clues. Their relatively shallow depth for example is below the level where the Seattle Fault is believed to lie, suggesting the activity could originate from another source.
A Big One is near?
While dozens of earthquakes have been reported on the Seismic Network’s website, a more in-depth review showed more than 500 events had occurred. Only a handful would have been large enough to have been felt by residents in the area.
They just don’t know! But keep saying don’t worry, there will be no Big One. BUT… The miniature quakes probably aren’t relieving pressure on the fault and lessening the chance of a more powerful earthquake. The earthquakes recorded so far simply haven’t been powerful enough to dispel the buildup of energy that would generate a larger event. Instead, earthquake swarms increase the probability of a larger earthquake taking place — though that possibility remains remote.
Causes of the swarm
Seismologists believe the shaking near Bremerton has occurred along a thrust fault that runs east-west below Puget Sound in an area where a plate beneath Washington is grinding north into a plate beneath British Columbia. Whatever its cause, Bremerton’s earthquake swarm showed no signs of letting up last week.
This swarm is a good reminder to be ready for the possibility of a larger earthquake. So Have your kits and plans ready and practice those plans often.