Getting Ready for The Big One
The City by the Bay minds history's lessons, sort of
SAN FRANCISCO--City Hall, destroyed in 1906, nearly toppled in 1989, is today a towering Beaux-Arts masterpiece. It's also the largest building in the world resting on what is essentially a rubber-and-stainless-steel spring that absorbs the energy of seismic waves before they reach the building's granite surface. But 5 miles away in the Sunset neighborhood, the situation couldn't be more different; sherbet-colored buildings with parking garages on the ground floor stand shoulder to shoulder, marching to the Pacific Ocean. This type of "soft story" housing is as uniquely San Francisco as cable cars, but the buildings, in part because of the way energy waves dance through them, are considered among the most likely candidates for total collapse in an earthquake.
And that's the yin and the yang of this city of 750,000, where everyone knows the big one could return at any moment. The U.S. Geological Survey says there's a 62 percent probability that one of the many faults that snake through the Bay Area will deliver at least one quake of 6.7 magnitude or stronger (on the moment scale) by 2032. In many fundamental ways, San Francisco is among the elite in preparedness, and yet it remains riddled with vulnerabilities. Experts have estimated that a major San Francisco temblor could cost the nation as much as $200 billion. What it would cost the City by the Bay is impossible to tell.
"Foreign fruit." On the face of it, California, a state sometimes dubbed "America's Disaster Theme Park," is certainly no stranger to living on the edge. And that's been instructive, more or less. The city of San Francisco that emerged from the ashes of 1906 boasted a few superwide streets to serve as natural firebreaks and a high-pressure auxiliary water system that allows firefighters to tap into a 10.5million-gallon basin reserved just for battling conflagrations. Much of the emergency response structure used by the U.S. Department of Homeland Security was "modeled after plans developed out in California," says George Foresman, the top DHS preparedness official. After wildfires ripped through the state in 1970, firefighters here crafted a basic organizational structure so they could quickly assemble teams of first responders for future blazes. That system, as well as the search-and-rescue-team concept developed here, has since gone national.
So San Franciscans were particularly rattled in 1989 when the Loma Prieta earthquake, a moderate 6.9-magnitude temblor, destroyed an Oakland highway overpass, collapsed a section of the city's double-decker Bay Bridge, and killed 67. "The great lesson of 1989," says Philip Fradkin, author of Magnitude 8, a book on earthquake history, "is that we were only prepared on paper. "Broken mains crippled the city's vaunted water system, and a raging fire in the tony Marina neighborhood was largely squelched by a fireboat that chugged into the harbor 30 minutes before low tide. Communications were so shattered that some far-flung Bay Area communities weren't heard from until the next morning.
In retrospect, that episode may have been something of a blessing, albeit an expensive one. Unlike many of the other 26 cities the U.S. Geological Survey says are most at risk for future temblors--a list that includes Boston, Memphis, and Charleston, S.C.--many residents of San Francisco now think about earthquakes frequently. "California's building codes," says James Lee Witt, former director of the Federal Emergency Management Agency under President Bill Clinton, "are the best of basically anyone's." In the past four years, the region has approved a $1 bridge-toll hike and more than $2 billion in bonds for a variety of seismic upgrades, including a project to strengthen the network of pipes that provides most of the city with water. On a recent night at the Golden Gate Yacht Club in the Marina, 65-year-old Lindsay MacDermid trained to become a neighborhood response team volunteer. "This city's going to need incredible help when the big one comes," MacDermid says. The active volunteer force already numbers 9,000. "San Francisco just gets it, and they got it long before Hurricane Katrina," says Jack Harrald, the director of George Washington University's Institute for Crisis, Disaster, and Risk Management. A city-sponsored website, for instance, says citizens should be prepared to wait three days after an earthquake for help. That's why the inevitable San Francisco-New Orleans comparison so rankles the city's public officials. "It's like comparing apples," says Annemarie Conroy, San Francisco's emergency services chief, "to some ... foreign fruit."
Nevertheless, the flaws in the city's landscape could still prove disastrous. Large swaths of San Francisco are built on sandy, uncompacted soils--or in some cases, ashes from 1906 and decomposing remnants of gold rush ships--that would turn into runny, liquidlike jelly when exposed to heavy shaking, a phenomenon called liquefaction. Among the plausible scenarios, says Mary Lou Zoback, a seismologist with USGS's Menlo Park office, are streets disappearing into 10-foot sinkholes. Earthquake waves in these zones could be magnified anywhere from three to 10 times in strength. Buildings not anchored in deep bedrock might tip on their foundations or sink into sludge during the shaking, sparking fires. The area's main highways run through valleys silted with weak soils. Those roads would crack like eggshells.
In the crazy-quilt patchwork of faults, there would be almost no safe haven. San Francisco's downtown core, filled with skyscrapers likely to shatter in a major earthquake, is equidistant from the San Andreas fault and the Hayward fault, a roughly 60-mile line that jogs through the Oakland hills, famously bisecting the University of California-Berkeley's Memorial Stadium. The Hayward is considered ripe for a quake: The past four were about 130 years apart, but it's now been 137 years since it last shuddered. "We have a gallows humor," says Mary Comerio, a Berkeley architecture professor and author of Disaster Hits Home. "When it comes, it's either us or Stanford."
"Sword of Damocles." Some of the area's problems, of course, are man-made. After a 50-foot chunk of the upper deck of the Bay Bridge collapsed in 1989, state officials waited until 1997 to deliver a blueprint for a safer design. Years of political squabbling ensued. Now the new structure won't be ready until 2013, although the bridge has been strengthened somewhat. "None of us," Zoback says of the current bridge, "believe the [Bay Bridge] will still be standing after the next earthquake."
For the Bay Area Rapid Transit subway system, the picture is equally grim. A 2002 study showed that in the event of a moderately strong quake, the Transbay Tube, the 3.6-mile subway tunnel under the San Francisco Bay, would come unhinged from its cocoon inside the bay mud and potentially crack and fill with water. In that scenario, the first four stations in San Francisco proper--all below sea level--might also be flooded.
More troubling still is a possible series of related calamities that could turn a Northern California earthquake into a pan-California nightmare. Oil refineries, some built before modern building codes, ring fault-crossed hills in the East Bay, where a temblor could also trigger mudslides down the Oakland hills. Residents of Silicon Valley, says author Fradkin, "probably aren't aware the Sword of Damocles is hovering above their heads." Earthen dams hold back the Lower Crystal Springs reservoir from the valley's northern rim; Fradkin says they probably withstood the Loma Prieta quake only because a drought lessened the pressure on their walls.
Most frightening is the prospect of breaks in the Delta levee system, a 1,600-mile network that provides water to 22 million Californians. An earthquake on the Hayward fault would most likely liquefy the levees, and the results, says Jeffrey Mount, the head of the Center for Watershed Sciences at the University of California-Davis, would be "diabolical." Floodwaters could surge into eroded basins of farmland, making it almost impossible to reverse the damage.
But as the old saying here goes, "It's not earthquakes that kill people; it's buildings." And the buildings are worrying lots of folks. An effort to fix unreinforced high-risk masonry buildings is still not complete. Critical structures like hospitals and public schools simply might not survive a quake. The Earthquake Engineering Research Institute estimates that immediately after an earthquake only 66 of the region's 484 hospital buildings could safely remain open. But Laurence Kornfield, the city's chief building inspector, worries most about those ubiquitous soft-story structures, many of them rent-controlled apartments shown to be the least likely to be retrofitted. City officials halted one study in 2002 that seemed to show that a third of the city's housing could be decimated or made uninhabitable by a repeat of the 1906 quake, leaving a quarter of a million homeless. Many of these folks, says Comerio, "are one paycheck away from homelessness already." And rebuilds wouldn't have to be under rent control.
But there are signs of hope. Kornfield is finishing that once tabled study now and hopes it will spark changes. In the meantime, he's thrown up a few skeletal house frames with garage doors in a parking garage near his office, bracketed them with $5 silver braces from a hardware store, and watched as the braces helped the frames stand up under test conditions mimicking an earthquake. "I'm about one step away from throwing these clips in a shopping cart," he says, "rolling down the street, and screwing them on thousands of garage doors myself." That's Plan B.
THAT SINKING FEELING
Large sections of the city could liquefy if there's a repeat of the 1906 quake.
AREA OF DETAIL
CALIFORNIA
San Andreas fault
Sunset
Richmond
Marina
Port of San Francisco
South of Market
The Embarcadero
San Francisco
Golden Gate Park
Fisherman's Wharf
Golden Gate Bridge
High risk of liquefaction in a 7.9-magnitude earthquake on the San Andreas fault
Sources: Association of Bay Area Governments, USGS
This story appears in the April 17, 2006 print edition of U.S. News & World Report.