A 6.0 earthquake that was centered near South Napa was recorded at 3:20 a.m. early Sunday morning, its epicenter about four miles northwest of American Canyon and six miles southwest of Napa, according to the Menlo Park-based United States Geological Survey (USGS).
The earthquake — said to be the largest to hit the Bay Area since the Loma Prieta Earthquake nearly 25 years ago — lies within the San Andreas Fault system that forms the boundary between the Pacific and North American tectonic plates.
USGS officials also reported 2.5 and 3.6 magnitude aftershocks about four miles southwest of Napa at 5:01 a.m. and 5:47 a.m., respectively, although up to 60 aftershocks were reported throughout Sunday. Officials have also said 30 to 70 small aftershocks could hit the area during the next week, though none will be as strong as the initial earthquake.
No damage was reported at Stanford, according to Brad Hayward, a University spokesperson, although several students on campus reported mild shaking and tremors.