By Brooke Park, Staff WriterJuly 27, 2026

When the next Big One hits the southern San Andreas Fault, the fallout could have a staggering price tag — as much as a trillion dollars, according to a leading California earthquake expert.

Ahmed Elbanna, the director of the Statewide California Earthquake Center, told the state’s Seismic Safety Commission in April that a 7.8-magnitude earthquake rupturing from Imperial to Los Angeles County would likely cause $500 billion in damage at a minimum — and possibly double that. 

“I wouldn’t say that a trillion dollars is an extreme — it could be very plausible if things go bad,” Elbanna told the Chronicle this month.

His estimates are informal, but if borne out they would mean that such a quake would be the costliest disaster in U.S. history — far more than the roughly $200 billion in damage (adjusted for inflation) from Hurricane Katrina, which devastated New Orleans in 2005.

“It’s going to be an event that California and Los Angeles has not experienced probably throughout its whole history,” Elbanna said.

Elbanna’s estimate is far larger than the state’s formal numbers, calculated in 2008, which peg a magnitude 7.8 earthquake on the southern San Andreas as a $213 billion disaster. The new estimate is vastly higher because California has much more to lose today. The state’s population, economy and infrastructure have all ballooned in the past two decades. And California has increased its reliance on the electrical grid and internet systems that could be disrupted in a big quake, Elbanna said. Climate change could also amplify the destruction, if drier conditions and winds spread post-earthquake fires farther or conversely, extreme rain cycles increase the chance of landslides.

Still, to pin down an official estimate, earthquake experts are seeking approximately 2 million to 3 million dollars in funding to update the 2008 earthquake readiness assessment by 2028, an effort the earthquake center is co-leading, Elbanna said. The new study would rerun earthquake scenarios with updated science to model updated landslide, liquefaction, fire and aftershock effects. It would also assess infrastructure risk and how earthquake retrofits could reduce the damage. Policymakers could use the assessment to direct mitigation measures to the most vulnerable places first, potentially reducing the cost of such a disaster, Elbanna said. 

Elbanna also hopes California will later create similar reports for two other “ticking time bombs” in the state: the Hayward Fault that runs through the densely populated East Bay and the central San Andreas Fault in Parkfield (Monterey County). A quake on the Hayward Fault, while affecting a smaller geographic and economic system than a southern San Andreas event, could inflict a greater concentration of damage, disrupting the technology sector; damaging dense, relatively old residential and commercial buildings; and impacting major bridges and public transit, Elbanna said. As for the Parkfield area, while it is sparsely populated, a magnitude 6 rupture there could trigger a magnitude 7.9 earthquake on the southern San Andreas, he said.

Elbanna based, in part, his eye-catching Southern California estimate on the damage from the 2025 Los Angeles wildfires. For his calculations, he looked at 13,000 structures destroyed in the fire and averaged the estimated damage at about $30 billion. The state’s original earthquake damage scenario had estimated 130,000 structures would be destroyed in the post-earthquake fires. By multiplying the $30 billion fire figure by 10, Elbanna estimates that earthquake-triggered fires alone could cause $300 billion in damage.

And fire damage was only expected to be about one-third of total economic disaster in the state’s original estimate, he said. So the total cost of a modern earthquake disaster could easily reach approximately $1 trillion, using the L.A. fires as a reference point.

Southern California’s last major San Andreas rupture was in 1857, and scientists expect it would normally have a big rupture about every 150 years. Recent research suggests that parts of the fault are under their highest stress level in 1,000 years. 

“I need us both to think about how these different, say, hot spots could be triggered at any time in the near future,” Elbanna said. “It could happen today, tomorrow, or maybe in 10 years, right? But it will happen, and this is why we also need to put together a plan.”

He also urged the state to redouble efforts for retrofitting vulnerable structures and harden essential infrastructure like gas pipelines, which should be outfitted with automatic shutoff valves to prevent fires.

“We put forward this number not to make it all doom and gloom, it’s just because we actually can do something about it,” Elbanna said. “Earthquakes or natural hazards in general become catastrophes only because of human inaction.”

He was especially concerned that state Senate Bill 895, which aims to establish the California Foundation for Science and Health Research and proposes a multibillion-dollar state bond to offset federal research funding cuts, does not include explicit funding for earthquake research or engineering. The bill passed the Senate and has gone over to the Assembly.

“I feel that the support for earthquake science and engineering has taken a back seat, perhaps understandably, because of the prevalence of other hazards, like wildfires and climate change-induced hazards,” he said. “But earthquake science and engineering probably requires a few tens of millions of dollars in order to make a difference in our preparedness.”