Why do people always talk about the Hayward Fault specifically as a hazard instead of other Bay Area faults like the San Andreas Fault?
There are two reasons for this. One is the time between quakes on these two faults. The 1868 earthquake on the Hayward Fault was considered the “Great San Francisco earthquake” until the San Andreas Fault ruptured in 1906. Before then, we did not know about the hazard of either fault. Our newest scientific studies show that earthquakes on the San Andreas Fault happen about every 200 years, while they happen on average every 140 years on the Hayward Fault. Do the math: 1868 + 140 = 2008, while 1906 + 200 = 2106. The San Andreas Fault appears not to be “due” as soon as the Hayward. The second reason is vulnerability: The San Andreas Fault runs along the hills of the Peninsula and is offshore from Pacifica to Stinson Beach. The Hayward Fault passes along the foot of the East Bay Hills, through Fremont, Hayward, Oakland, etc. Many more people live directly on the Hayward Fault than on the San Andreas Fault. In addition, much of the infrastructure that supports the people in the Bay Are
