Study Predicts Larger Earthquakes for Northern California

The Bay Area is at risk of even bigger earthquakes than previously predicted, according to a new comprehensive study published in the Bulletin of Seismological Society of America on Monday.

The latest research cites four particular faults as major sources of concern: the Hayward Fault between Suisan Bay and San Jose; the Rodgers Creek Fault in southern Sonoma County; the Green Valley Fault in Solano County; and the Calaveras Fault, which runs from Hollister to Danville. Scientists say all rifts are moving on the surface, and are liable to rupture at any time.

The Green Valley Fault in particular “is likely to have a larger earthquake than people previously thought,” said James J. Lienkaemper of the U.S. Geological Survey in Menlo Park, who led the study. The fault, which is long overdue for a rupture, could produce an earthquake of magnitude 7.1. The Hayward Fault, meanwhile, runs directly beneath a massive amount of infrastructure, making any potential impact all the more devastating.

“The extent of fault creep controls the size and timing of large earthquakes, and measuring that creep rate helps tell us how much strain is building up on the faults underground — although it can’t tell us when a fault will rupture in a quake,” Lienkaemper said.

The latest study comes just two months after Napa’s 6.0-magnitude temblor—and just days before the 25th of anniversary of the devastating Loma Prieta quake. Experts say great progress has been made since 1989, but there is still plenty of room for improvement.

"A lot has been done," said Anne Kiremidjian, professor of civil and environmental engineering at Stanford University, who gave preparedness efforts a C+. "But to get a B,” she added, “there's a lot more to be done.”

Read more about the latest study here.