SEATTLE (TNS) A magnitude 4.6 earthquake shook Seattle and the Puget Sound region just before 3 a.m. local time Friday, according to the United States Geological Survey.
Its been widely felt throughout the Seattle area, said Paul Caruso, a USGS geophysicist.
The shaking emanated from Three Lakes, Snohomish County, about nine miles east of downtown Everett. The earthquake was relatively shallow, originating about 14 miles beneath the surface, according to a USGS map.
There were no immediate reports of damage in Snohomish County, according to a tweet from the Sheriffs Office. Police in nearby Lake Stevens reported no damage to city infrastructure. The Washington State Department of Transportation said in a tweet that the agency would be inspecting bridges Friday morning, but had no reports of damage.
A second quake, measured at magnitude 3.5, was reported near Monroe a few minutes afterward. A handful of smaller aftershocks followed, according to the Pacific Northwest Seismic Network.
Initial USGS reports had described the larger trembling as a magnitude 4.4 earthquake that began less deep in the earths surface.
Caruso said the earthquake was the product of a thrust fault, in which one side of a fault pushes upward in relation to its opposite side.
Thrust faults are common in the Cascade Range, Caruso said.
He said the earthquake did not have any connection to recent tremors in California, and that it was too shallow to have originated in the Cascadia subduction zone off the Washington coast, where stress and strain has been building for a long time.
Joan Gomberg, a USGS seismologist and affiliate faculty member at the University of Washington, said the likelihood of a bigger one is small. Its not impossible, but its small.
She said scientists were working Friday morning to better quantify those chances.
The biggest fault near the earthquake is the Southern Whidbey Fault Line, but Gomberg said researchers dont suspect this event occurred on that fault.
Scientists think another fault, further beneath the earths surface where scientists have less understanding, is likely responsible. That fault is probably not mapped and likely lacks surface expression features like cracks in the ground or offsets in topography that can be spotted with powerful lidar surveying technology, Gomberg said.
If theres earthquakes, theres a fault, Gomberg said. There has been activity in this same spot previously.
The larger earthquake was felt across the Canadian border, the USGS map reports. People reported feeling the earthquake to the south in Olympia, to the west in Port Angeles and to the east in Wenatchee.
Kieran Smith, 23, a Western Washington University student in Bellingham who lives in a fourth-floor apartment, said he felt his bed shake and the building sway.
