A preliminary 3.9 magnitude earthquake struck in northern Mendocino County Friday afternoon, according to the United States Geological Survey. The quake hit at 3:05 p.m. and was centered 7.1 miles north-northeast of Covelo, 51.1 miles north of Ukiah and 55.4 miles west-southwest of Red Bluff, the USGS said. This is a developing story. Details may change as more information becomes available. Stay tuned for updates. BAY AREA QUAKE CENTRAL You can take steps to plan and prepare for the next big one. Access our Bay Area Quake Tracker, the latest earthquake stories, extensive quake prep checklists, videos and many other disaster preparedness resources all in one place: NBCBAYAREA.COM/QUAKES ...read more read less