Tsunami study finds Southern California at risk

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Boats collide with one another after a tsunami surge of water swept through a boat basin in Crescent City, Calif., on March 11, 2011.

Boats collide with one another after a tsunami surge of water swept through a boat basin in Crescent City, Calif., on March 11, 2011.

A large tsunami hitting California would cause major flooding in Long Beach and parts of Orange County and force 750,000 people to evacuate coastal areas in just a few hours, according to an extensive simulation published Wednesday by the U.S. Geological Survey.

The study, released two years after a tsunami killed thousands in Japan, identified several communities that are particularly vulnerable to flooding because of their low elevation and lack of protection from waves.

They include Marina del Rey and the ports of Los Angeles and Long Beach as well as the low-lying coastal areas extending from the ports to Newport Beach.

The report, compiled by dozens of scientists, emergency responders and industry representatives, is the most extensive examination of what a tsunami would do to California’s coastline. The research simulated a 9.1 quake off the Alaska coast that would send damaging waves to California.

While waves would be larger in Northern California — between 10 and 23 feet — the damage could be greater in Southern California because the region has more coastal development and fewer coastal cliffs.

Tsunami waves of 3 to 10 feet could submerge blocks of Long Beach south of Ocean Boulevard, including the Aquarium of the Pacific and the Long Beach Convention Center as well as the Shoreline Village and Pike shopping centers. Those same-sized waves could cause flooding around the affluent communities of Newport Bay and Huntington Harbour as well.

California has been preparing for decades to deal with major earthquakes. But only more recently have officials begun extensive tsunami planning, including establishing evacuation routes in coastal cities. The research for the simulation was expanded after Japan’s tsunami focused more attention on the risk, said Lucy Jones, the U.S. Geological Survey seismologist who led the project.

“The idea is to say: Look, these are not distant events, these could actually happen here,” said Kathleen Tierney, director of the Natural Hazards Center at the University of Colorado Boulder. “This is meant to get

tsunamis on the public’s radar.”

Under the study’s scenario, the first waves would hit Crescent City, in the far north of the state, in as little as four hours. The waves would then make their

way down the coast, arriving in San Diego two hours later.

Researchers said the waters would cause sewage to foul beaches, damage fishing boats in marinas and make more than 8,000 people homeless.

Tsunamis could also travel several miles inland up coastal rivers. Statewide, one out of three boats in coastal harbors and ports could be damaged or sunk, and the cost of the disaster could approach $8 billion.

The biggest challenge would be evacuating everyone before the tsunami hits. Some areas, like Balboa Island in Newport Beach, have only narrow roads for escape routes.

During summer beach season, evacuation could be significantly more difficult. More than 250,000 people at beaches and coastal parks would have to evacuate in the spring. And that number jumps to 1 million in the summer.

“Your life depends on how you respond,” Jones said. “People die in tsunamis. They’re very, very deadly, but we do have time. We have a few hours.”

Unlike earthquakes, which millions of Californians can recall vividly, tsunamis are rare enough that few coastal residents have experienced them, making it difficult for local officials to know how seriously people might take evacuation warnings.

The study’s simulation involves a temblor that hits Alaska just before noon on March 27, 2014, which would be the 50th anniversary of the tsunami caused by a 9.2 earthquake in Alaska in 1964.

A tsunami as powerful as that created in the simulation is estimated to occur once every several hundred years.

There’s little recorded evidence of a destructive tsunami in Southern California in modern times. But the 1964 Alaska tsunami killed 10 people in Crescent City.

Courtesy of Los Angeles Times

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