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.
Within a minute the 3.5 quake hit near Monroe.
Shocking footage of those earthquakes showed food falling from the shelves of grocery stores and waves sloshing in residents' swimming pools.
Authorities have not issued any tsunami warnings or advisories, and no serious injuries or damage has been reported yet.
Surveillance video obtained by CBS affiliate KIRO-TV showed the moment the quake hit Everett, Washington.
An overnight natural disaster with an epicentre around 65 kilometres north of Seattle was felt in British Columbia.
The state Department of Transportation sent crews out to inspect bridges but no damage was found by Friday afternoon.
Joan Gomberg, a USGS seismologist and affiliate faculty member at the University of Washington, said "the likelihood of a bigger one is small".
Initial USGS reports had described the larger trembling as a magnitude 4.4 natural disaster that began less deep in the earth's surface.
A flurry of seismic activity in Snohomish County has people on edge after two earthquakes, magnitudes 4.6 and 3.5, shook the area.
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. Thrust faults are common in the Cascade Range, Caruso said.
There isn't a connection between this natural disaster and the ones that rocked California earlier this month, Steele said.