The U.S. Geological Survey reported three minor earthquakes between Saturday evening and Sunday morning in the Black Hills area south of Mount Diablo.
The largest was a 2.5 magnitude earthquake that occurred at 10:38 p.m. Saturday about 2.5 miles north-northeast of Blackhawk. The epicenter sits between Mount Diablo State Park and Morgan Territory Regional Preserve. The quake’s center depth was recorded at about 5.5 miles.
A magnitude 2.1 preceded at 6:48 p.m. Saturday and another magnitude 2.2 followed early Sunday at 3:27 a.m.