The first struck at Three Lakes, Washington, and the second 4km west of the city of Monroe.
There were no reports of damage or injuries following these quakes, and a tsunami was not expected according to the US National Tsunami Warning Centre.
One woman tweeted “we just had an earthquake here in Seattle. Our bed was shaking and hitting the wall,” adding it “felt so strong.”
Despite no damage or tsunami risk, residents in the area are on edge following two huge quakes which struck less than a week ago.
These quakes were followed by thousands of aftershocks, and residents fear more are on the way.
The 7.1 quake which struck on July 5 was felt from Sacramento down the west coast into Mexico – and was the most powerful earthquake to hit California for two decades.
After the California quake, seismologists have warned Washington state should prepare for a big tremor as well.
Harold Tobin, director of the Pacific Northwest Seismic Network at the University of Washington, warned “something similar could happen in Seattle.”
He told Komo News: “Let’s say one on the coast.
“A big one on the Cascadia fault will be felt strongly in Seattle and will be amplified.
“Our fault that we worry about the most for the really big one for the Pacific Northwest is this offshore fault called the Cascadia Fault or Cascade Subjection Zone.
“That’s the one that could give us the magnitude 9. The big tsunami.”
Both California and Washington State lie on the explosive ring of fire, a horseshoe-shaped area in the Pacific Ocean.
This area stretches 25,000-miles long and is home to around 90 percent of the world’s earthquakes and more than 75 percent of the world’s active and dormant volcanoes.