The U.S. Geological Survey reported a magnitude 3.6 earthquake Thursday morning about 15 miles north of Soledad. The quake was reported just before 8 a.m. at a depth of about 6 miles.
This follows a series of shakers in the East Bay, with a 4.5 magnitude near Pleasant Hill on Monday night that temporarily interrupted operations at two petroleum refineries in Martinez and a 3.2 magnitude in the same area Tuesday evening.
Smaller temblors, a 2.9 and a 2.7, have also been reported in the Geysers area at the eastern edge of Sonoma County.
Thursday is the 30th anniversary of the 6.9 magnitude Loma Prieta Earthquake of 1989, which killed more than 50 and caused damage in a half-dozen counties.