March 31, 2005 —
A new University of Southern California study, which appears in the April edition
of Civil Engineering magazine, finds that the potential damage from a local tsunami in Southern California
could range from $7 billion to as much as $42 billion.
The report is the first attempt to calculate possible losses from tsunamis, as
opposed to earthquakes, in the Southern California area.
This map shows the maximum runup from the tsunami modeled by the USC group.
a landslide on the sea floor off the Palos Verdes Peninsula, it could inundate
areas around the
Ports of Long Beach and Los Angeles, as well as low-lying communities in coastal
Entitled "Could It Happen Here?" the article builds on research by Jose Borrero,
assistant research professor of civil engineering, and Costas Synolakis, professor
of civil engineering, at the USC Viterbi School of Engineering regarding tsunamis
caused by underwater landslides in unstable sediments off Palos Verdes peninsula.
Synolakis is director of the USC Viterbi School Center for Tsunami Research.
A tsunami in this area could inundate Terminal Island and much of the ports of
Los Angeles and Long Beach, as well as producing substantial run-up on Orange
County beach cities, with maximum waves arriving only one minute after the slide.
Municipalities potentially affected include Carson, Long Beach, Wilmington/San
Pedro, Palos Verdes Estates and Rancho Palos Verdes, Seal Beach, Westminster,
Garden Grove, Huntington Beach, Hawaiian Gardens, and unincorporated areas of
Los Angeles and Orange Counties.
The study uses methodology co-created by one of the authors, Harry W. Richardson,
who holds the James Irvine Chair in Urban and Regional Planning at the USC School
of Policy, Planning and Development, with a PPD colleague, Professor Peter Gordon.
This scheme breaks down Southern California into 308 zones, whose individual contribution
to the area's economy is noted in detail, along with their economic connections
to other zones.
Researchers used an improved version of the system, called the Southern California
Planning Model, to incorporate effects caused by damage to the highway system.
James Moore II, who chairs the Viterbi School's Daniel J. Epstein department
of industrial and systems engineering, worked with Richardson on the application
of the model to a tsunami.
"We have not attempted to account for the cost of fatalities in our estimates,"
said Moore. "We chose not to model fatalities because we were being deliberately
conservative, and because we wanted to avoid contentious assumptions about the
economic value of life." Moore noted that "the Papua New Guinea tsunami of 1998
was generated by a mechanism similar to the one modeled here, and that event cost
over 2,000 lives. The toll here could be much higher."
The study assumed four possible scenarios, of increasing severity. In scenario
1, losses were confined to inundated areas, with no freeway links closed, and
no crippling damage to the ports of Los Angeles/Long Beach.
The following 3 scenarios assumed escalating problems, with a worst case being
closure of critical freeway links and the
ports for one year, forcing the shipment of $83 billion in exports now going
through these facilities elsewhere.
The study also breaks down direct losses by municipality, with Long Beach suffering
some $3.6 billion in damage, by far the largest for any single city.
The authors note that these losses, significant as they are, would be only a
part of a general picture of damage. The most likely trigger of a landslide off
Palos Verdes would be a large earthquake -- which itself would produce billions
"However, it is important to remember that these tsunami costs would be incurred
in addition to earthquake costs," the authors note.
In addition to Borrero, Moore, Richardson and Synolakis, Sungbin Cho contributed
to the article.
Click on the image above to download a pdf copy of the original story, "Could
It Happen Here,"
as published in Civil Engineering.
A number of animations of tsunamis off the Southern California coast can be seen
at the USC
Viterbi tsunami site's video animation page, at
(Note: the specific tsunami modeled in the Civil Engineering paper is not displayed)