Sunday, 2 August 2026, 16:02
A new study suggests the risk of "The Big One" in California could be greater than previously believed. Scientists have long warned that the San Andreas Fault is capable of producing some of the state's largest earthquakes. The fault is the longest in California and therefore capable of the biggest earthquakes, said Dr. Lucy Jones, a seismologist at Caltech who helped develop a 2008 simulation of a magnitude 7.8 rupture.
That simulation produced nearly two minutes of shaking and projected hundreds of deaths and billions of dollars in damage if such an earthquake occurred along the southern section of the fault.
Researchers led by geophysicist Liliane Burkhard of the University of Bern found that stress levels along parts of Southern California's fault system may be higher than previously understood. Because Southern California has not seen a major San Andreas earthquake since 1857, stresses have built up over centuries. In some places, they are now the highest observed in all of the past 1,000 years, Burkhard said.
Jones compared the potential Southern California rupture to a powerful earthquake that struck Venezuela in June. That quake, she said, began west of Caracas and then ruptured toward the city, focusing energy into heavily populated areas. "We think that'll happen here as well," Jones said.
Researchers highlighted Cajon Pass, where the San Andreas and San Jacinto faults meet, as a site where a significant earthquake could damage critical infrastructure across several cities. Water supplies are especially vulnerable. "Aqueducts actually cross the San Andreas Fault, and if something happens, you might not have water for a while," Burkhard said.
California has spent decades preparing for major earthquakes through mandatory building retrofits and updates to building codes. But Jones warned that the consequences of a major quake would go beyond physical damage.
"We underestimate the social disruption and the economic disruption. We are so focused on our fear of dying, that we forget to be afraid of being bankrupted," Jones said.
Experts continue to encourage residents to retrofit their homes, maintain emergency supplies and establish communication plans. During shaking, Jones said the safest response is simple: "Drop, cover, hold on."
Southern California's cities, water systems and transportation corridors depend on infrastructure that crosses the San Andreas Fault. The Cajon Pass area is a vital connection for rail, utilities and highways. A major rupture there could disrupt daily life well beyond the immediate epicenter, affecting millions of residents.
The San Andreas Fault has produced some of California's most powerful historic earthquakes, including the 1857 Fort Tejon earthquake and the 1906 San Francisco earthquake. The 2008 simulation was created to help residents and agencies understand what a modern big one might look like and to encourage preparation.
The new study does not make earthquakes predictable, but it does sharpen the picture of pressure building beneath Southern California. Scientists still say the fault could go another 100 years or could rupture tomorrow. The message is consistent: prepare now, because a major earthquake may be closer than anyone expects.
