The USGS says the quake was centered in the Pacific Ocean, about 70 miles west of Ferndale, and struck at 4:16 a.m. Thursday. It was originally logged as a magnitude-5.3 temblor.
Since the downgrade, this Northern California earthquake is tied for the biggest earthquake of 2015 (so far!) with another magnitude-5.1 temblor that shook Firuzabad, Iran at 3:49 a.m. local time, according to the USGS.
The Victorian village of Ferndale sits about 100 miles south of the Oregon state line and about 275 miles northwest of Sacramento.
An officer with the Ferndale City Police Department said some slight shaking was felt in the area early Thursday, but no damage or injuries were reported.
The earthquake was about 250 miles northwest of the epicenter of a magnitude-6.0 temblor that caused extensive damage in Napa and the surrounding area on Aug. 24.