The study, commissioned by the U.S. Geological Survey, set the probability of such a quake at 62 percent. The last time the survey was conducted, in 1999, the estimate was 70 percent. A major quake has a magnitude of 6.7 or greater.
David Schwartz, the study's co-author, noted that area residents face a greater chance of experiencing a significant quake than being affected by such well-publicized threats as anthrax.
"The things we face every day - when we turn on the TV, or read the newspaper - in many ways will never touch us," Schwartz, head of the USGS San Francisco Bay Area Earthquake Hazards project. "But living in this region, earthquakes will affect us.
Earthquakes are going to happen."
Schwartz presented the research during a public lecture at the University of California, Berkeley.
The Bay Area's last major earthquake, with a magnitude of 6.9, occurred in 1989. Centered 50 miles south of San Francisco, the quake killed 40 people and caused about $6 billion in structural damage.
Researchers have said the devastation would have been much worse if the quake's epicenter had been closer to the region's urban center.
Today, the most potentially hazardous of the region's seven major faults is the combined Hayward-Rodgers Creek system, according to the study.
The Hayward fault roughly parallels the densely populated Interstate 880 corridor, while the Rodgers Creek fault extends north of San Francisco into the city of Santa Rosa.
The study also said the region has just a 10 percent chance of seeing an earthquake of magnitude 7.5 or greater.
The most significant seismic event in the Bay Area in the last century was the magnitude 7.9 San Francisco quake of 1906.
By Beth Fouhy