Graphic explains how a shift in the ocean's floor can trigger a tsunami. MCT 2010.

By Alia Wilson

Santa Cruz Sentinel

(MCT)

SANTA CRUZ, Calif. – Officials are closing beaches across Santa Cruz County in California and warning residents to stay off jetties after the National Weather Service announced a tsunami advisory following the massive 8.8-magnitude earthquake in Chile Saturday.

Devastating waves aren’t expected to hit the California coast, but officials don’t want to take any chances.

Diana Henderson, a forecaster with the National Weather Service, said an advisory is issued when waves are expected to increase in height by less than a meter. She said waves are expected to hit the Santa Cruz coastline around 1:25 p.m. PST.

“We’re not by any means evacuating people,” Henderson said. “We advise everyone to pretty much stay away from the water.”

Henderson said Santa Cruz could be hit harder than other areas.

“Santa Cruz is in a precarious place,” she said. “This tsunami is coming from the south and Santa Cruz is south-facing so there may be more damage compared to other areas. It will be hitting Santa Cruz right in the face.”

Henderson said waves are expected to reach 3.3 feet at the highest.

“It won’t be just one single wave, it could be an inundation and may last a good portion of the day,” she said. Santa Cruz Harbor Patrol began putting written notices on people’s boats around 6 a.m. local time.

“We don’t know how this is going to affect us but we are planning for the worst and hoping for the best right now,” Harbormaster Chuck Izenstark said. “We are doing the best we can to advise all live-aboards, the general public and beachgoers that there is a tsunami advisory. We are going out to close beaches and jetties to the public until the event is cleared.”

Harbor Patrol officers were patrolling beaches and warning people of the advisory on Saturday. An evacuation plan is also in the works as a precaution. State Parks officials closed all the state beaches in Santa Cruz and San Mateo counties early Saturday morning and moved about 30 people from the campground at Seacliff State Beach to higher ground, according to State Parks Lifeguard Supervisor Chip Bockman.

Bockman said the beaches probably would remain closed for a couple hours past the advisory period because there may still be strong currents and waves.

“Were erring on the side of safety and keeping the beaches closed,” he said. “(People should) stay high and dry above beach level and off the sand at least a couple hours past the advisory period.”

Santa Cruz Fire and its Marine Rescue Division were to shut down Main Beach and Cowell Beach at 1 p.m. until the advisory passes. The Boardwalk and the Santa Cruz wharf stay open.

“If it was a tsunami warning rather than advisory it would be our policy to evacuate the wharf,” Battalion Chief Matt McCaslin said. “But because it’s an advisory we’re comfortable with leaving the wharf open.”

The beaches in Capitola also closed although some restaurants along the Esplanade were still open. The patio at Margaritaville remained open as the staff prepared for a normal business day.

“The sun’s out, people are in here, I don’t think anything will happen,” Assistant General Manager Jeremy McCarthy said. “Police came down at 10:30 this morning to let us know we will be getting an automated call about the advisory. I asked if we needed to sandbag it up but the police said they highly doubt anything will happen. So our doors are open.”

Capitola police are patrolling the beaches and the Village to advise people about the warning.

“We are prepared to close off streets if necessary,” Sgt. Matt Eller said. “Most businesses are closing up shop on their own doing. Right now, we are informing the public and will go from there.”

In September 2009, Coastal California, including Santa Cruz County, was included in a tsunami advisory after an 8.0 temblor struck American Samoa. The advisory prompted State Parks rangers and lifeguards to close beaches early and relocate some campers in low-lying areas; however, the tsunami size was measured in inches.

The National Weather Service’s tsunami advisory includes the entire West Coast.

The weather service is advising everyone in coastal counties to stay away from beaches and shorelines Saturday afternoon when a tsunami producing strong currents and a series of potentially dangerous waves was expected to hit the coast at around 1:25 p.m.

The advisory includes the Bay Area counties of San Francisco, Santa Cruz, San Mateo, Marin, Monterey, Contra Costa, Napa, Sonoma, Santa Clara and Alameda.

In November 2006, quake-generated wave action rocked the harbor after an 8.1-magnitude undersea temblor in Japan. The surge lasted about six hours, turning the water from blue-green to brown in the harbor and snapping the dock lines on a handful of boats.

There have been six tsunamis large enough to cause significant damage along the coast of California over the past 200 years, according to Gary Griggs, Santa Cruz Sentinel columnist and director of the Institute of Marine Sciences and Long Marine Laboratory at the University of California-Santa Cruz.

In that period, 16 people died as a result of the tsunamis; one of the deaths was in Santa Cruz. On April 1, 1946, a man drowned while walking along Cowell Beach when water rose 15 feet above normal quickly from a large earthquake in the Aleutian Trench off Alaska, according to Griggs.

Crescent City on the state’s North Coast was hit hard by a tsunami from the huge Alaskan earthquake of 1964. Water levels rose 8 feet, and much of the low-lying downtown area was inundated as waves washed 2,000 feet inland, drowning 11 people and destroying 150 businesses, according to Griggs.

In Santa Cruz, water levels at the harbor surged 11 feet. A 38-foot boat and a dredge sunk.

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(c) 2010, Santa Cruz Sentinel (Santa Cruz, Calif.).

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