In the San Francisco Bay Area, more than 400,000 could be displaced in a magnitude 7 earthquake on the Hayward fault, which directly runs underneath cities like Berkeley, Oakland, Hayward and Fremont, said Ken Hudnut, the U.S. Geological Survey’s science advisor for risk reduction. And it’s possible that more than 250,000 people in Southern California could be forced out of their homes after a major earthquake on the San Andreas fault, Hudnut said. Not everyone will need to stay in public shelters — many will stay with relatives, friends and hotels. Still, more than 175,000 people may have no other...