The San Andreas long has been the fault many Californians feared most, having unleashed the great 1906 earthquake that led to San Francisco’s destruction 112 years ago Wednesday.
But new research shows that a much less well-known fault, running under the heart of the East Bay, poses a greater danger.
A landmark report by the U.S. Geological Survey estimates that at least 800 people could be killed and 18,000 more injured in a hypothetical magnitude 7 earthquake on the Hayward fault centered below Oakland.
Hundreds more could die from fire following an earthquake along the 52-mile fault. More than 400 fires could ignite, burning the equivalent of 52,000 single-family homes, and a lack of water for firefighters caused by old pipes shattering underground could make matters worse, said geophysicist Ken Hudnut, the USGS’ science adviser for risk reduction.
“This fault is what we sort of call a tectonic time bomb,” USGS earthquake geologist emeritus David Schwartz said. “It’s just waiting to go off.”
The Hayward fault is so dangerous because it runs through some of the most heavily populated parts of the Bay Area, spanning the length of the East Bay from the San Pablo Bay through Berkeley, Oakland, Hayward, Fremont and into Milpitas.
Out of the region’s population of 7 million, 2 million people live on top of the fault, Schwartz said, and that proximity brings potential peril. The 1989 Loma Prieta earthquake was centered in the sparsely populated Santa Cruz Mountains. For all the devastation of the 1906 San Francisco earthquake, it was centered off the coast in the Pacific Ocean.