If a monster earthquake struck off Alaska's coast, tsunami waves would rush toward California, swamping the nation's largest port complex and causing major economic damage.
That's according to a hypothetical scenario released Wednesday by the U.S. Geological Survey and others to help emergency planners prepare.
Tsunamis are a rare but real threat in California. After the 2011 Japan disaster, tsunami waves surged across the Pacific and damaged the Northern California commercial fishing village of Crescent City.
San Diego’s coastline didn’t see the damage suffered by Northern California. The high-range expectation here was 2.6 feet, but the actual surge was less than a foot.
A group of experts used the example of a 9.1 magnitude centered striking between Kodiak Island and the Shumagin Islands off the Pacific coast of the Alaska Peninsula in March 2014 and developed reports on damage and injury assessments.
The state’s history with tsunami damage has been fortunate, the report suggests.
“There is strong reason to believe that California faces a tsunami threat that could realistically cause billions of dollars in losses and, although we have not discussed it here, substantial loss of life,” the Science Application for Risk Reduction (SAFRR) tsunami scenario states.
In the scenario, it would take six hours for the initial waves to arrive to San Diego giving local authorities the ability to evacuate those living or working along the coastline.
The shape of the state’s landscape means the tsunami hazard in the SAFRR scenario would be generally less in southern California than elsewhere along the California coast.
However, scientists say a closer offshore quake would create more havoc, flooding the ports of San Diego, Los Angeles and Long Beach and forcing coastal communities to evacuate and destroying boats and small craft.
Waves created by a quake of that magnitude in that location would damage or sink a third of the boats in marinas along the state’s coastline and would damage or destroy more than half the docks.
Experts say fires would likely start at where fuel is stored in ports and marinas.
In addition to residents or employees who may be in zones considered at risk during the scenario, USGS estimates 260,000 tourists would need to be evacuated statewide – a number that could jump to more than a million in the busy summer tourist season.
The damage left behind would range from environmental (erosion of shorelines or contamination) to economical.
A shutdown of commerce in and out of major ports could last more than two days and result in billions of dollars in lost revenue the report suggests.
The tsunami scenario is similar to a quake exercise released several years ago designed to prepare for a big one on the San Andreas Fault.
USGS experts will participate in workshops scheduled with different cities and counties throughout the state including one scheduled Friday in San Diego.