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Tsunami's ripple currents to be seen on Southern California beaches [Updated]

March 11, 2011 |  8:19 am

Southern California beaches are expected to be hit within a half-hour with unusual ripple currents from the massive 8.9 earthquake in Japan.

Most beaches are likely to see 1- to 3-foot waves starting around 8:30 a.m., said Bill Patzert, an oceanographer at Jet Propulsion Laboratory in La Canada-Flintridge. Unlike typical waves, the force of the current is expected to build slowly and could last up to a half-hour.

“These are not going to be waves we’re used to seeing in Hollywood movies,” Patzert said. “Most waves tend to last for 20-30 seconds. The waves we’re going to see will last 20-30 minutes.”

Photos: Scenes from the earthquake and tsunami

Waves generated by the tsunami are 300 to 500 miles long and move at 500 mph in the open ocean, Patzert said.

[For the record at 9:44 a.m.: An earlier post stated that waves generated by the tsunami are 100 feet long. They are 300 to 500 miles long.]

“We are definitely on high alert, but nothing like we’re going to see in Japan,” Patzert said.

According to the National Weather Service, those living in tsunami warning areas near the beach or in low-lying regions “should move immediately inland to higher ground and away from all harbors and inlets, including those sheltered directly from the sea."

"Those feeling the earth shake, seeing unusual wave action, or the water level rising or receding may have only a few minutes before the tsunami arrival and should move immediately. Homes and small buildings are not designed to withstand tsunami impacts.”

But a tsunami expert at USC says California should catch a lucky break from the tsunami just now reaching the West Coast.

“Tsunamis tend to be highly directional and spread out across the ocean in fingers of energy –- they’re called fingers of God,” said Costas Synolakis, a professor of civil and environmental engineering in a phone call from Greece where he was attending a science conference. “It appears that this tsunami is not going to have significant energy” pointed in California’s direction.

Still, Synolakis said some port areas and portions of the central and northern coasts could see significant surges.

Regardless of how the ocean appears, he advised people to keep away from the beach.

Synolakis recalled that last year, in the wake of an earthquake in Chile, a tsunami brought a surge of about 2.5 feet in Santa Monica and onlookers were seen exploring the sea floor as it withdrew.

“You should not do this,” he said. Tsunamis are unpredictable and an initial surge isn’t necessarily the last -– or highest –- one. “We do not want people sitting on the beach watching the shoreline moving back and forth.”

Videos of the earthquake

On Friday, California should know the extent of the tsunami’s effect by about 9 a.m., he predicted.

Harbor areas and some cove-like areas in Laguna Beach are likely to see a visible change, he said. Currently a number of beach closures around the Southland are in effect.

At least one school in Newport Beach, Newport Elementary School, announced an emergency closure Friday because of the tsunami alert. The school is on the Balboa Peninsula. The Newport Beach Police Department closed harbors and beaches to try to keep public activity to a minimum.

A lower-level tsunami advisory was issued for the Southern California coast south of Point Concepcion, which includes southern San Luis Obispo County and the counties of Ventura, Los Angeles, Orange and San Diego.

In San Diego, lifeguards and fire-rescue personnel are asking people to stay away from the water but are not ordering the closure of beaches. No Navy ships have been ordered to sea but line handlers are on alert if that order comes. A Navy ship at the Seal Beach weapons station was ordered to sea as precaution. 


Hawaiians brace for 6-foot tsunami waves

Massive tsunami threatens Pacific Rim after Japan's biggest quake in 140 years

--Nate Jackson, Mike Anton and Tony Perry

Photo: People watch for any change in the tidal surge from Sampson Overview Gazebo at the end of Blue Lantern in Dana Point. Credit: Don Kelsen / Los Angeles Times


Click on map icons to see National Oceanic and Atmospheric Administration's estimated time of arrival of waves along the California coast. Source: NOAA and Google maps