Next 'Big One' in San Francisco could kill 5,000

SAN FRANCISCO - An earthquake on the San Andreas fault as large as the one that destroyed San Francisco a century ago could kill thousands and cause US$150 billion in damage, scientists said on Monday on the eve of the 100th anniversary of the city's 1906 quake.

Areas near the shorelines of San Francisco Bay, especially landfill, are particularly vulnerable. A repeat of the 7.9-magnitude 1906 quake on the San Andreas fault could kill between 3,000 and 5,000 people in San Francisco and in the surrounding region, said Lloyd Cluff, director of geoscience at utility PG&E Corp., in an interview.

Some 200 buildings in San Francisco's Financial District, which sits where part of the city's waterfront once was, are likely to collapse in a big shake because they predate improvements in building codes, said Cluff.

And older apartment buildings converted to single-room occupancy hotels in the city's poor Tenderloin District are also likely to pancake into the streets, he said.

Despite spending billions of dollars to strengthen bridges, buildings, railways, water lines and power grids since the magnitude 6.9 Loma Prieta earthquake struck in October 1989, a major earthquake could still produce widespread devastation.

The Loma Prieta quake, which killed more than 60 people, was centered about 60 miles south of San Francisco in the Santa Cruz mountains and collapsed one freeway in Oakland and severely damaged the Bay Bridge connecting the city with San Francisco.

The Loma Prieta quake is being forgotten as the region focuses on the anniversary of the 1906 earthquake along the San Andreas near San Francisco. Historians say the quake killed roughly 500 people while ensuing fires claimed another 2,500 lives.

But scientists warn other nearby faults are equally dangerous. The Hayward fault running beneath Oakland, Berkeley and the crowded East Bay suburbs across the bay from San Francisco is more likely to trigger the region's next killer quake, according to many earthquake experts.

Mary Lou Zoback, regional coordinator for the US Geological Survey, said a 7.0-magnitude shock on the Hayward fault, where 2 million people live, would move the earth 4 to 8 feet and sever highways, gas pipelines, the power grid, pipes that carry drinking water to San Francisco from Yosemite Valley, and commuter rail lines.

"All of the infrastructure crosses the fault. Anything directly in the path of that earthquake will not survive that kind of movement," Zoback said. Repairs could take months.

According to experts, a 7.9-magnitude temblor along the San Andreas fault that hits the San Francisco Bay area would seriously damage as many as 10,000 commercial buildings and leave as many as 250,000 households without homes across the region. Much of the region's infrastructure could be crippled.

San Francisco, at the tip of a peninsula, gets most of its electricity from high-voltage transmission lines delivering power from plants outside the city.

PG&E has added new transformers, switching equipment and other gear to its electric substations to withstand a strong quake and keep power flowing during an emergency. There is also a plan to place a new transmission under the bay to supply the city.

- REUTERS