On any given day, 680,000 Californians go about their business in tsunami hazard zones. If a tsunami were to strike, it could cause up to $12.6 billion in damage and thousands of casualties across 20 coastal and bayside counties.
Depending on the type of tsunami, residents could get anywhere from six hours of notice to a 10-minute warning.
The Los Angeles Times has run through several scenarios based on information from the California Tsunami Program, managed by the California Governor’s Office of Emergency Services and the California Geological Survey. According to the Times:
Del Norte County is considered to have the largest tsunami risk. A tsunami in Del Norte County could kill or injure 3,150 people. Neighboring Humboldt County could see 720 deaths.
Flooding from a tsunami reach up to 30 feet above the average high tide in the Humboldt Bay and Eureka areas. Near Crescent City, flooding could reach up to 50 feet.
In the Bay Area, a distant-source tsunami could kill up to 1,300 people. About 500 of those deaths could occur in San Francisco. San Mateo and Marin counties could each see 300 casualties with another 200 in Alameda County.
Waves from a distant-source tsunami could reach 32 feet at San Francisco’s Ocean Beach, 31 feet in Pacifica, 27 feet in Bolinas, and 18 feet in Alameda.
A near-source tsunami could produce waves between 7 and 9 feet in Sausalito, Pacifica, and Bolinas.
Over 350 people could die or get injured along the Southern California coast during a distant-source tsunami, including about 200 deaths in Los Angeles County, 80 in San Diego County, 60 in Orange County and about a dozen in Ventura County.
A near-source tsunami could produce waves between 9 to 30 feet in Malibu, Redondo Beach, Two Harbors, Palos Verdes Hills, and Avalon.
In the event of a distant-source tsunami, over 230 people could die or face injury along the Central Coast, with around 130 deaths in Santa Cruz County, 80 in San Luis Obispo County, and 16 in the County of Monterey.
A near-source tsunami could produce 15-foot waves in the City of Marina, 9-foot waves at the Salinas River, and waves of 8 feet at the Pajaro River and Sand City.
“Tsunamis are a rare but real threat to our community," Reginald Harrison, director of disaster preparedness and emergency communications for the city of Long Beach, told the Times. State and local officials must prepare, not just for the ever-present threat of earthquakes, but also for the tsunamis that may follow.
Read more about California’s tsunami risk and the most at-risk cities and counties here.