A magnitude 3.6 earthquake struck Napa County just after midnight Thursday.
The U.S. Geological Survey recorded the quake at 12:36 a.m. along Hardin Creek, about 7.5 miles southeast of Angwin and west of Lake Berryessa at a depth of 2.9 miles.
Five aftershock quakes followed with the last one recorded at 4:21 a.m. The smaller tremors ranged in magnitude from 1.6 to 1.9.