CALIFORNIA STATE – California’s long-feared “Big One” could cause as much as $1 trillion in damage if a major earthquake strikes the southern San Andreas Fault, according to one of the state’s leading earthquake experts.
Ahmed Elbanna, director of the Statewide California Earthquake Center, recently warned that the financial consequences of a magnitude 7.8 earthquake could be dramatically higher than California’s existing estimates suggest.
Elbanna reportedly told the California Seismic Safety Commission in April that a quake rupturing the San Andreas Fault from Imperial County toward Los Angeles County could cause at least $500 billion in losses. Under particularly destructive conditions, he believes the total could reach $1 trillion.
Such a disaster could become the costliest in United States history, surpassing the inflation-adjusted losses associated with Hurricane Katrina.
California’s Main Estimate Is Nearly 20 Years Old
The eye-popping new estimate does not mean scientists have suddenly detected an earthquake about to strike. Earthquakes still cannot be reliably predicted by date and time.
Instead, the warning reflects how much California has changed since researchers produced the state’s landmark ShakeOut earthquake scenario in 2008.
That scenario examined what could happen if a magnitude 7.8 earthquake began near the Salton Sea and traveled northwest along the southern San Andreas Fault.
Researchers estimated that the disaster could kill roughly 1,800 people, injure about 50,000 and produce approximately $213 billion in losses. It also projected widespread fires, building damage, water shortages and prolonged disruption to transportation and other critical services.
But nearly two decades of inflation, construction and population growth have made that estimate increasingly outdated. California has also become more dependent on interconnected electrical, communications and internet systems whose failure could disrupt businesses far beyond the areas experiencing the strongest shaking.
Elbanna’s $1 trillion estimate is not yet the conclusion of a new comprehensive state study. It is an informal projection intended to show how severely the old figures may underestimate the modern risk.
Fires Could Be Among the Biggest Costs
One of the most alarming parts of the scenario is what could happen after the ground stops shaking.
Broken gas lines, electrical failures and damaged water systems could allow fires to spread while firefighters struggle with blocked roads and limited water pressure.
Elbanna reportedly used the destruction from the 2025 Los Angeles-area wildfires as one reference point. Those fires destroyed roughly 13,000 structures and caused an estimated $30 billion in damage.
The original ShakeOut scenario projected that post-earthquake fires could destroy about 130,000 structures — approximately 10 times as many. Applying the recent wildfire losses to that much larger disaster produces a rough fire-loss estimate of $300 billion.
Fire accounted for only about one-third of the total economic damage in the original earthquake scenario. When structural damage, business interruption, utility failures and other losses are added, Elbanna believes a total approaching $1 trillion becomes plausible.
Climate-related hazards could make the aftermath even harder to manage. Dry conditions may increase fire danger, while intense winter storms could trigger landslides in areas destabilized by shaking.
The Warning Matters in the Bay Area, Too
The specific $1 trillion projection involves a southern San Andreas Fault earthquake, but Northern California faces its own potentially devastating threats.
The U.S. Geological Survey has estimated a 72% probability that at least one magnitude 6.7 or larger earthquake will strike the San Francisco Bay Area before 2043.
Of particular concern to East Bay residents is the Hayward-Rodgers Creek fault system, which runs through one of the country’s most densely developed and economically interconnected regions.
A major Hayward Fault earthquake could damage homes, freeways, BART tracks, water lines, electrical systems and communications infrastructure across Alameda, Contra Costa and neighboring counties.
The East Bay’s last major Hayward Fault earthquake occurred in 1868. Scientists have studied evidence of repeated large earthquakes along the fault and consider it one of the Bay Area’s most serious seismic risks.
A New Study Could Produce a Clearer Number
Elbanna and other experts are calling for a comprehensive update to California’s earthquake-loss modeling.
A modern assessment would examine the state’s current building stock, infrastructure, population and reliance on digital technology. It could also account for inflation and lessons learned from recent earthquakes, fires and other disasters.
The proposed project is expected to require approximately $2 million to $3 million in funding.
Until that work is completed, the $1 trillion figure should be understood as a warning about what is plausible — not a precise forecast of what a particular earthquake will cost.
For California residents, the central message remains familiar: strengthen vulnerable buildings, secure heavy furniture, prepare emergency supplies and make a family communication plan before an earthquake occurs.
California’s statewide warning system may provide residents with several seconds of notice before strong shaking arrives. Officials recommend enabling emergency alerts or downloading the MyShake app and immediately dropping, covering and holding on when an alert is received.
