Tsunamis present a significant threat to California’s coastline, and experts warn that a major tsunami could have devastating impacts. More than 680,000 Californians could find themselves in danger if a tsunami strikes during the day. The potential damage could reach a staggering $12.6 billion across 20 coastal and bayside counties. This estimate does not even account for the destruction of infrastructure like ports and roads.
There are two types of tsunami scenarios to consider. The first is a "distant-source" tsunami, which can occur after a major earthquake far away, like one in Alaska. In such cases, residents could have several hours of warning—about six hours for Los Angeles and five for San Francisco. However, these tsunamis can still cause significant flooding across large areas.
The second type is a "near-source" tsunami, which can hit coastal areas in as little as 10 minutes after an earthquake. This leaves little time for evacuation, making it particularly dangerous.
In Southern California, if a distant-source tsunami were to occur, it could lead to over 350 casualties, with the highest numbers in Los Angeles County. A hypothetical 9.3 magnitude earthquake from Alaska could generate waves as high as 15 feet in certain areas. The damage from such an event could exceed $1.4 billion.
For near-source tsunamis, Los Angeles could experience waves reaching 30 feet, particularly if an underwater landslide occurs. This scenario is alarming because the tsunami could arrive before any warning is issued.
The Central Coast is also at risk. A distant-source tsunami could result in more than 230 casualties, with Santa Cruz County facing the highest risk. The damage from such an event could top $3.5 billion. Near-source tsunamis could bring waves of up to 15 feet in some areas.
In the Bay Area, a distant-source tsunami could lead to over 1,300 casualties if people delay evacuation. The potential damage could surpass $6.5 billion. Near-source tsunamis could generate waves reaching up to 9 feet.
The North Coast, particularly Del Norte County, faces the highest risk due to its proximity to the Cascadia subduction zone. If an earthquake occurs, flooding could reach up to 50 feet in some areas, putting thousands at risk.
These scenarios highlight the urgent need for preparedness. California residents living near the coast should be aware of the risks and know how to respond in case of an emergency.