California north coast shaken by magnitude 5.1 earthquake near Eureka

A series of offshore earthquakes shook near California's North Coast early Wednesday morning.

The quakes included a magnitude 5.1 earthquake about 40 miles west of Petrolia, which struck at 5:45 a.m., and a larger magnitude 5.7 earthquake that struck just before 4 a.m. farther offshore, west-southwest of Pistol River, Oregon.

Minutes after the Petrolia-area quake, an apparent aftershock registering as a magnitude 4.5 earthquake struck in nearly the same area.

The Petrolia-area quakes were very shallow, with preliminary depths of less than a mile below the seafloor.

USGS impact estimates for the larger quakes were low, and no major damage was expected. No tsunami warning, advisory, watch or threat was in effect, according to the U.S. Tsunami Warning Center.