Odds Of Major Bay Area Quake Tops 74%. Here's When The Big One Could Hit: Report

SAN FRANCISCO, CA — There's nearly a three-quarters chance that the next large earthquake will hit the Bay Area sometime in the next 30 years, according to new calculations by the U.S. Geological Survey.

The USGS re-evaluated the data at the San Francisco Chronicle's request, something the federal agency hadn't done in more than a decade.

The new calculations show that, across all faults, there is a 74.1% chance the Bay Area will be struck by a magnitude 6.7 or stronger earthquake in the next 30 years, a slight 2% increase from the previous study, according to the report.

"It's reinforcing what we already know," United States Geological Survey geophysicist Kevin Milner told NBC News. "That we have to be prepared for a major earthquake. It is going to happen in most of our lifetimes."

The San Andreas Fault saw the largest jump among the fault lines, according to the report. There is a 25.5% probability that a major earthquake will happen there in the next 30 years, according to the San Francisco Chronicle report.

That's a 3.6% increase from the previous study's forecast, according to the San Francisco Chronicle report.

In the collective imagination of Californians, "The Big One," the colloquial name for the anticipated, catastrophic earthquake expected to rupture along a major fault line like the San Andreas, looms large.

Although studies, podcasts, disaster films, and articles attempt to prepare Californians for what "The Big One" could look like, scientists in this latest study say there's no way to know.

Scientists don’t know if it would resemble the cataclysm of 1857, when a quake as powerful as 7.9 tore open the San Andreas from Monterey County clear through Los Angeles County. Nor can we be sure it would mirror the devastation of 1906, when the San Francisco earthquake struck just offshore and ripped the fault in two directions — one tearing north toward Humboldt County, the other south toward Santa Cruz.

“Earthquakes never come back exactly the same way,” Solene L. Antoine, the study’s lead author and a postdoctoral fellow at Caltech, told the Los Angeles Times in 2025.

Most Californians tend to focus on "The Big One," and its potential damage. But most hazards come from events like the magnitude six earthquake in 2014 near South Napa," Sarah Minson, a research geophysicist with the USGS Earthquake Science Center, said last year.

"You can prepare for earthquakes, and they’re very survivable," Minson said. "California is well built for earthquake safety... Your building is not supposed to be a threat to your life in an earthquake," she said, but added that hazards remain inside.

"You can have bookcases, things that can fall on your head. Right now I’m looking up at the ceiling tiles in my office," she said. "So what we say is, if you feel shaking, please drop, cover, and hold on to protect yourself from anything that might fall on you."

Most injuries, she added, come from people trying to move during quakes — tripping, falling, or running outside where facades or air conditioning units may fall.

Preparedness is key.

"It’s going to be just as tragic if [a family heirloom] gets knocked over in a magnitude five as if it gets knocked over in a magnitude eight," she said.

"And the ways that you prepare for earthquakes are really handy for all sorts of disasters... Being prepared for one really helps you be prepared for all of them."

California Editor Kat Schuster contributed to this report.