Just a week after a magnitude 3.9 earthquake rattled Oakland’s Hayward Fault, new research is turning the spotlight back on California’s most infamous seismic threat—the San Andreas Fault. Scientists at San Jose State University have uncovered evidence that a stretch of this fault, particularly in the Santa Cruz Mountains of Northern California, has been slipping at a faster and more consistent rate than previously believed. The implications of this discovery have the potential to reshape how Californians think about earthquake risk and preparedness.
Professor Kim Blisniuk, an earthquake geologist at San Jose State, spoke with ABC7 Eyewitness News and other outlets about the findings. According to Blisniuk, her team’s research analyzed landform changes along the San Andreas Fault over the past 10,000 years—a significant expansion compared to previous studies, which typically focused on the last 1,000 years. “And so the great aspect of this work is that it is a rate of which the landform preserves previous earthquakes along the fault,” Blisniuk explained. “And the rate is similar to the rate that we get for the San Andreas Fault to the north in the north coast section. But prior to the work that my colleagues and I did at Sanborn County Park, the rate appears to not decrease along the San Andreas Fault, but it appears to be constant over this 10,000-year window that we were able to document.” (ABC7)
This steady, faster slip rate matters—a lot. In geology, faults that move more quickly tend to produce earthquakes more frequently, increasing the probability that a significant quake could strike at any time. As Blisniuk put it, “We know that we live on a plate boundary, and we are always surprised when we hear, ‘Oh my gosh, an earthquake occurred in Japan or Colombia,’ but we are going to have an earthquake in California, and we should be prepared.” (ABC7)
The San Andreas Fault, often dubbed the “mother of all earthquake faults,” has a storied and sometimes tragic history. The 1906 San Francisco earthquake, which devastated large portions of the city and sparked massive fires, and the 1989 Loma Prieta earthquake, which famously collapsed a section of the Bay Bridge and caused widespread destruction, both occurred along this fault zone. These events serve as stark reminders that California’s seismic past is never far from its present reality.
The new research, while still awaiting peer review and formal publication, builds on a growing body of evidence suggesting that both the northern and southern stretches of the San Andreas Fault are under significant strain. Earlier in the summer of 2026, a separate study from the University of Hawaii found that the southern section of the San Andreas Fault near Los Angeles has reached its highest stress level in 1,000 years. According to the San Francisco Chronicle, the Cajon Pass—a critical junction where the San Andreas and San Jacinto faults meet—is also at stress levels not seen in a millennium. The lead author of that study warned that the Cajon Pass could facilitate a joint rupture of both faults, a scenario that could be far more devastating than a single-fault event.
Blisniuk’s research, however, focuses squarely on the northern segment, specifically the Santa Cruz Mountains, and reveals that the slip rate here has remained constant for about 10,000 years. This consistency was unexpected. “I don’t think the idea that the slip rates are and constant along the San Andreas Fault, where we have studied, it is a big surprise to a lot of people. We just didn’t have that data before,” Blisniuk told ABC7. The new data suggest that the potential for major earthquakes in Northern California may be just as pressing as concerns in the south.
Of course, the research is not without caveats. As of August 2026, the findings have not yet been published or peer-reviewed. Blisniuk hopes to present the work at a conference in October, after which the United States Geological Survey (USGS) will have the opportunity to review and comment on the findings. Until then, the results should be viewed as a strong indication rather than a definitive conclusion. Still, earthquake experts and public safety officials say that the message is clear: Californians cannot afford to be complacent.
Blisniuk urges residents to take preparedness seriously, likening it to buying insurance. “I always use the example of insurance. We always want auto insurance. We buy auto insurance, home insurance. We never want to use it, but it’s there for us,” she said. “And so, having an earthquake preparedness kit to prepare us for a potential disaster when an earthquake occurs will really help us deal with the trauma of having an earthquake.” (ABC7)
For those who need a refresher, earthquake preparedness kits should include water, non-perishable food, flashlights, batteries, first-aid supplies, and copies of important documents. It’s also wise to have a family plan in place, know how to turn off gas and electricity, and secure heavy furniture and appliances. These steps may seem routine, but as history has shown, a few moments of preparation can make all the difference when disaster strikes.
While the new findings are based on the northern San Andreas, the implications ripple across California. Los Angeles, for example, sits squarely on the fault’s southern section, and the recent University of Hawaii study only heightens concerns about the region’s vulnerability. The possibility of a joint rupture at the Cajon Pass, where the San Andreas and San Jacinto faults meet, is particularly worrisome. Such an event could be significantly more damaging than any single-fault earthquake, potentially affecting millions of residents and causing untold economic disruption.
Despite the seriousness of the research, Blisniuk and her colleagues emphasize that the new data do not indicate an imminent earthquake, but rather underscore the need for ongoing vigilance. As Blisniuk told the San Francisco Chronicle, “This is not new movement—it’s new data and a good reminder to be prepared.”
Californians are no strangers to seismic risk, but this latest research serves as another wake-up call. The land beneath their feet is in constant motion, and while scientists can’t predict exactly when the next big quake will hit, they can say with certainty that preparation is not optional. With new insights into the fault’s unyielding pace, the stakes for readiness are higher than ever.
As the research community awaits further review and analysis, the message remains the same: stay alert, stay informed, and, above all, stay prepared. The San Andreas Fault isn’t slowing down—and neither should efforts to get ready for what comes next.