February 24, 2005

New Tsunami Warning System Installed at Ocean Beach

By Daniel Porras
Special to the Neighborhood Newswire

On an unseasonably warm afternoon at Ocean Beach, surfers ride the waves while kite flyers, lovers, and families enjoy the sun and breeze. To some city officials and regional scientists, though, Ocean Beach is not just San Francisco’s popular sand and surf retreat, but a potential disaster zone – ground zero for the next big tsunami to hit the Pacific Northwest.

Ocean Beach is the focal point for a new Tsunami preparedness plan sponsored by the San Francisco Office of Emergency Services (OES). The plan was under development before recent tsunamis in Southeast Asia caused massive destruction. OES is banking on a new system of warning sirens to move people to higher ground at a moment’s notice, a measure that could save thousands of lives.

According to Annemarie Conroy, OES’ Executive Director, the new system is “capable of sounding a warning siren, and also acts as a multi-language public address system.” In ethnically diverse Ocean Beach, residents and beach-goers would hear a live message in their native tongue telling them to rush to higher ground, or instructing them where to catch a Muni bus for evacuation. According to Darcy Brown, OES’ Chief of Administration, staff capable of speaking any likely language are available around-the-clock.

The new warning system, due to be fully operational by March, is a step-up from San Francisco’s antiquated system, a network of 50 air raid sirens installed during World War II, of which only 18 are still functioning. The new plan replaces the old sirens – which emit a whine that alerts people to nothing in particular - with an advanced public address system consisting of 65 strategically-located sirens. While the sirens can be used to warn citizens of all manners of impending doom, the OES is particularly interested in earthquakes and tsunamis. After all, geologists say faults off the West coast, like the Cascadia subduction zone, are ominously similar to the one that recently snapped off the coast of Sumatra.

“The [tsunami] we are prepared for is twice the size of the one that hit Southeast Asia,” says Ms. Brown. After securing a $2.1 million Federal Homeland Security Grant, the OES prepared a plan to cope with a 50-foot tsunami, an earthquake-generated wave that could easily rush three or four blocks into the neighborhoods around Ocean Beach. But, Brown adds, a tsunami that size “is a long shot.” Nonetheless, the OES has an extensive tsunami plan that requires the cooperation of the Department of Telecommunications and Information Services, the Recreation and Parks Department, the Department of Public Works, and the San Francisco Unified School District. In addition to the new public address system and various evacuation plans, the OES launched a new website, 72hours.org, named for the advice that all families should have on hand at least 72 hours worth of emergency supplies, including batteries, flashlights, food, and water.

Tsunamis, from the Japanese tsu – meaning harbor, and nami – meaning wave, are often mistakenly referred to as tidal waves. The giant waves have nothing to do with incoming or outgoing tides, however. Tsunamis can be triggered by either seismic or non-seismic events, and can originate locally or thousands of miles away, says Elena Suleimani, a tsunami modeler at the Geophysical Institute at the University of Alaska. Non-seismic events include landslides, nuclear explosions, and meteorite impacts.

At Ocean Beach, a tsunami scenario could unfold like this: Geologists in Alaska would detect a large seismic event in the Pacific Ocean and would call the State of California Office of Emergency Services, who would notify San Francisco. San Francisco’s OES would then activate the new public address system, which would give residents information and instructions on how to evacuate. The chain of events could give residents as much as an hour – or as little as ten minutes – to clear out.