At 3:54 a.m., an earthquake with a preliminary magnitude of 2.5 shook an area of Concord, according to the USGS, and had a depth of 9.3 miles.
Ninety seconds later, a second, slightly larger quake struck the same area. According to the USGS, the second event had a preliminary magnitude of 2.6 and a depth of 9.1 miles.
