- The last time a sizable earthquake occurred on the Hayward Fault was on October 21, 1868; it has been estimated at a magnitude between 6.8 and 7.2. According to scientists at the University of California, Berkeley, the average span between the last five major earthquakes on the fault was 140 years.
- The Hayward Fault is part of the San Andreas Fault system — which serves as the point of connection between the North American and the Pacific tectonic plates — and travels from the Gulf of California to Cape Mendocino in the north.
- According to the USGS, reports of being affected by the earthquake on the Hayward Fault over the weekend came from the East Bay, San Francisco and the San Francisco Peninsula.
