Federal scientists have increased the estimated odds of a major earthquake striking California's Bay Area for the first time since 2014. The US Geological Survey (USGS) now calculates a 74.1 percent chance of at least one magnitude 6.7 or stronger earthquake hitting the region by 2055, a slight increase from the previous estimate of 72 percent.
A quake of this magnitude could cause significant damage to homes, roadways, and essential infrastructure throughout the densely populated Bay Area. According to seismologist Ned Field of the USGS, "Things seem to be pretty locked and loaded. We’d be wise to be ready." This updated forecast suggests that for millions of residents, the primary concern is not whether a destructive earthquake will occur, but when.
The new forecast utilizes the same statewide earthquake model, the third Uniform California Earthquake Rupture Forecast, that was employed for the 2014 assessment. This system identifies faults capable of producing earthquakes of various magnitudes and estimates the likelihood of such events.
For the latest assessment, researchers updated the model's starting point to 2026, incorporating the additional years that have passed without major ruptures in certain fault sections. The estimate includes any earthquake whose rupture zone enters a designated area stretching from Santa Rosa in the north to Monterey in the south.
Among the major faults in California, the Hayward-Rodgers Creek fault system presents the greatest individual risk, with its probability rising from 33.1 percent to 34.3 percent. The San Andreas Fault saw the largest increase in odds, with a jump of 3.6 percentage points, from 21.9 percent to 25.5 percent. The Calaveras Fault now has a 26.8 percent probability of generating a major earthquake, up from 25.6 percent.