Two, much stronger earthquakes shook the state last weekend and triggered thousands of aftershocks.
The initial temblor was recorded at 2:51 a.m. Friday. There were no early reports of injuries and the U.S. Geological Survey (USGS) said there was no tsunami risk. The second - measured at magnitude 3.5, occurred near Monroe a few minutes later.
A 4.6 magnitude quake rumbled from near Monroe early Friday morning, shaking buildings to the southwest around Seattle while most of Capitol Hill slept through the ride. "We are spooked and still awake", Rob Fuhriman told the station.More news: Announcement scheduled for new British GP deal
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The Northwest is especially prone to earthquakes.
A 4.6-magnitude quake is relatively benign, but it comes just six days after a magnitude-7.1 quake struck Southern California, the region's worst in 20 years.
Caruso said the Northwest quake had no connection to the recent earthquakes in California.