California at Serious Risk from Tsunami

Posted on December 12, 2005

The California Seismic Safety Commission has issued a report that says a large tsunami is a serious threat to human life in California. A tsunami could also have a devastating impact on the state's economy. The report includes analysis based on the deadly 2004 tsunami in Southeast Asia. The report found the the casualty count could be very high from a large tsunami.
Casualties. As the 2004 Sumatran tsunami amply demonstrated, a large tsunami poses a major risk to human life, primarily from flooding and debris impact. Evacuation is possible and can save many lives if carried out properly. However, a poorly coordinated evacuation can actually put people in harmís way. Moreover, the short time frame between event and tsunami for local events requires that the local population be aware enough of the appropriate action to evacuate without official notification. Of the five Pacific states, California has the largest population exposed to tsunami risk. NOAA has estimated that more than one million people in California live within coastal areas vulnerable to tsunami inundation (the rushing in of the water causing flooding and battering by debris). That number does not include one million or more visitors to California's beaches on any given summer day.
A PDF version of the report can be downloaded from the California Seismic Safety Commission's website. The report is interesting because it takes a close look at the water depth near the California coast to determine which parts of the coast will see the biggest tsunami. The report says that the Cascadia subduction zone will produce the California's largest tsunami. A LiveScience.com article about the report noted the potential huge financial impact a powerful tsunami could have on the coast of California.
Along with threatening lives and property, a giant tsunami would strike an economic blow to the state, given the vulnerability of its ports, the report said.

If a tsunami shut down the ports of Los Angeles and Long Beach for two months, the economic loss could reach $60 billion. The ports make up the third busiest port in the world, but its docks and terminals are only about nine feet above the water. A separate report issued March concluded a Southern California tsunami could cost at least $42 billion.

A massive wave higher than that could cause extensive damage, the report said. Thousands of pleasure boats and other crafts could come loose, and vehicles, equipment, containers and tools could get washed away.
The report also found that there are flaws in the warning system, evacuation plans and building codes -- all of which will need to be improved so that California can avoid a massive loss of life like the world saw from 2004's tsunami.