Minutes later, a 3.5 magnitude after shock was recorded further south in Monroe.
Two earthquakes shook the Puget Sound region in Washington state early Friday morning, with the temblors felt into British Columbia and across the Cascade Mountains into the eastern part of the state.
There are reports of items falling off walls and shelves but no reports of damage.
The tremor, which hit the Three Lakes area of Washington State, less than 20 km from Everett, was measured at magnitude-4.6 around 2:51 am today.
An interactive map on the USGS website shows several dozen people in the Vancouver area reported feeling the shaking. The quake was felt around the sound from Arlington to Seattle and as far as Bremerton, CBS affiliate KIRO-TV reported.
A day earlier, B.C. recorded a 6.2-magnitude quake between Vancouver Island and Haida Gwaii but it was unrelated to the one in California.
Caruso said the quake was the product of a thrust fault, in which one side of a fault pushes upward in relation to its opposite side.