The Brief A magnitude 4.3 earthquake struck in the Bay Area on Tuesday night. The quake struck east of Cloverdale in Sonoma County. The U.S. Geological Survey measured a magnitude 4.3 earthquake Tuesday night near Cloverdale. Sonoma County earthquakeWhat we know:The earthquake struck at 7:40 p.m. and was recorded about 5 miles east of the Sonoma County town at a depth of greater than 3 miles. page on on USGS' website recorded reactions to the earthquake, including light or weak intensity in San Francisco and to the north in Ukiah.