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April 09, 2006

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Disastrous consequences likely in invitable SF Quake!

John Ritter
USA Today
Apr. 9, 2006 12:00 AM

SAN FRANCISCO - Hurricane Katrina was bad enough. But consider what an earthquake like the monster that devastated this city 100 years ago would do today.

More than 300,000 people left homeless. Thousands of buildings collapsed or damaged beyond repair. As much as $200 billion in economic losses. Two major airports knocked out. Freeways crumbled and sunken. Mass transit disrupted. Water pipelines shattered. A number of fires fueled by broken gas lines.

Picture one of America's greatest cities, perched on a peninsula, cut off when bridge approaches fail. Commuting all but stops. Ships and military airlifts become the bearers of emergency food and supplies. Tent cities and makeshift trailer parks persist for months as a region already chronically short of housing struggles to rebuild. advertisement 
 
That is a doomsday scenario that the Red Cross, the U.S. Geological Survey, city and state disaster agencies and private engineering firms believe is not only possible but likely. "My going-in position? It won't be pretty," says Kevin Kellenberger, disaster services director for the American Red Cross Bay Area Chapter.

The 'Big One'
The magnitude-7.8 earthquake of April 18, 1906, and its aftermath of fire and disease killed an estimated 3,000 people across an area whose population is 10 times as great today. In a repeat of that earthquake, one of the United States' worst catastrophes, several thousand would perish, the Geological Survey estimates.

Arguably no other earthquake-prone spot in the world is better prepared for the "Big One" than the San Francisco Bay area, nine counties and 6.7 million people living atop seven active earthquake faults.

Tens of billions of dollars has been spent to fortify buildings, bridges, roads, dams and power stations, much of it since the Bay area's last big quake, Loma Prieta, in October 1989. Thirty years of construction under tougher seismic building codes have created an inventory of structures better able to withstand Earth's violent shaking.

But thousands of old buildings still need reinforcing, says Chris Poland, president of Degenkolb Engineers in San Francisco. Seismic upgrades on critical infrastructure remain unfinished: a span of the Bay Bridge damaged in 1989, the aging tunnels and pipes of a water system supplying 2.5 million people, $1 billion in retrofits on Bay Area Rapid Transit lines.

Many hospitals and schools couldn't withstand a major earthquake, state studies show, and few have money for seismic strengthening. Older concrete buildings, apartment and condominium towers among them, were built with inadequate reinforcing steel and are at risk of collapse in a major earthquake, Poland says.

It's not a matter of if but when the next one will strike. The Geological Survey, the government's chief earthquake research agency, puts the odds of a repeat of 1906 at 1 in 25 in the next 25 years.

Fault lines
The notorious San Andreas Fault that produced the 1906 earthquake has ruptured repeatedly over millenniums. Stress builds gradually along the fault deep in Earth's crust, then lets loose in an instant like the snap of a rubber band. Scientists can observe stress buildup but can't predict the time and place of the snap.

The longer the rupture, the stronger the earthquake. In seconds, at a speed of up to 13,500 mph, nearly 300 miles of the San Andreas ripped apart in 1906 - as much as the fault is capable of, the Geological Survey says. The epicenter was 2 miles offshore from San Francisco's Golden Gate Park, yet Santa Rosa, 60 miles north, was flattened and had the highest per capita death toll, 117. Forty miles south, the then-new Stanford University campus lay in ruins.

In 1989, just 25 miles of the fault ruptured, enough to produce a magnitude-6.9 earthquake that killed 63 people and left $6 billion in damage. Small bumps in magnitude carry a big wallop: The magnitude-7.8 earthquake in 1906 was 30 times more potent than the magnitude-6.9 in 1989.

Across the bay from San Francisco and the San Andreas looms another disaster-in-waiting: the Hayward Fault coursing through a dense urbanscape including Oakland and Berkeley.

Northern California had a strong earthquake every few years in the 1800s but none big enough to spoil San Francisco's rowdy emergence as the West's most populous and sophisticated city. Earthquake science was primitive, seismic building codes non-existent.

Deadly aftermath
The jolt was violent and destructive, but the fires that followed, wind-driven and superhot, accounted for at least 80 percent of the damage. Nearly 500 blocks burned. More than half the city's 400,000 residents were homeless amid staggering rubble. The water system failed, leaving no supply for drinking, much less fighting fires. Service wasn't restored for three months. Crowded, unsanitary camps and shelters bred plague.

Earthquake-hazard research emerged, and scientists for the first time mapped, on horseback, the San Andreas Fault, 800 miles from near the Salton Sea in the Mojave Desert to Cape Mendocino south of Eureka. They found that it had ruptured repeatedly and that earthquakes appeared to be cyclical.

Later investigation revealed six other major faults running parallel at 10- to 20-mile intervals through northern California.

Today, designating a building "earthquake resistant" It doesn't mean business as usual. "The public thinks it means no damage," says Richard McCarthy, executive director of the California Seismic Safety Commission. "It means you and I get out of that building alive, but the next day they start tearing it down."

Politics and scarce resources inevitably affect earthquake preparedness. "When you're cutting back services to your community every day because of budget constraints, there won't be the political will to spend money on something that may never happen," says Frances Edwards, a former San Jose emergency services director.