According to the data, four major faults in the region are moving along the surface and are primed to collide in a huge way. These stressed faults “are locked and loaded,” geophysicist James Lienkaemper, lead author of the study published online Tuesday in the Bulletin of the Seismological Society of America, told the Wall Street Journal.
However, Lienkaemper added, “nature doesn’t tell us when she’s going to pull the trigger.”
The faults of concern, all of which run under urban areas, are the Hayward (between Suisun Bay and San Jose), the Calaveras (from Hollister to Danville), the Green Valley (near Richmond and Fremont) and the Rodgers Creek (in Sonoma County).
Lienkaemper explained to NBC News that if the faults are locked as they appear, one of them will eventually give way as the Pacific Plate moves past the North American Plate, causing quakes anywhere from magnitude 6.8 to 7.1. That’s right in the range of the Loma Prieta earthquake 25 years ago, which took 63 lives.
Lienkaemper estimates a nearly 70 percent chance that one of those faults will pop within the next three decades, and he named the Hayward fault as the most likely to rupture.
A scientist who didn’t work on the study confirmed that the findings seemed plausible.
“Given how long ago they had their last earthquakes, they are more than ready to produce a major earthquake again now,” Roland Burgmann, a University of California, Berkeley geophysicist told the San Francisco Chronicle.
Napa County is still recovering from an Aug. 24 earthquake, which killed one resident and injured approximately 100. Measuring at magnitude 6.1, the quake was the largest to hit the Bay Area since Loma Prieta.