The Brief
- Seismologists reviewing Washington’s largest earthquake of the year—a magnitude 4.2 quake 18 miles underground near Gig Harbor—determined it occurred beneath the Tacoma Fault and was followed by at least four unfelt aftershocks.
- Phone alerts were not broadcast because the earthquake fell below the magnitude 5 threshold required for automated public alerts.
- Officials are using the recent shaking to urge participation in the upcoming Great ShakeOut drill on Oct. 15, reminding residents to check emergency kits and practice dropping, covering, and holding on.
SEATTLE – A magnitude 4.2 earthquake in Gig Harbor prompted roughly 10,000 Washingtonians to report feeling the shaking. In the days that followed, at least four aftershocks were too small to feel, according to Harold Tobin, director of the Pacific Northwest Seismic Network.
Now, about two weeks after the earthquake, seismologists are reviewing what it revealed about the region’s faults as Washington prepares for its annual Great ShakeOut drill.
“Every earthquake like this, lights up in a sense for us a little spot in the earth’s crust that tells us just a little bit more about the patterns of earthquakes and the faults in our region,” said Tobin.
What seismologists learned
The backstory:…