A 4.0-magnitude earthquake struck San Francisco area on Thursday followed by a smaller 3.8-magnitude quake within six hours, the U.S. Geological Survey said. No damage or injuries were reported while trains operated by Bay Area Rapid Transit experienced minor delays, local authorities said.
The aftershock hit at about 8:15 p.m. following an initial earthquake that struck the area at 2.31 p.m. The stronger first quake was centered across the bay from San Francisco, the U.S. Geological Survey reported. Both earthquakes were centered close to the University of California, with the first one being six miles deep while the aftershock was about nine miles deep.
In 1989, the 6.9-magnitude Loma Prieta earthquake hit the area injuring almost 3,800 people and causing damages worth $10 billion during the 1989 World Series. Some 8 million Californians took part in an annual preparedness drill, named the Great California ShakeOut, on the same day when the two earthquakes struck the San Francisco area.