San Francisco centennial

At the beginning of the 20th century, San Francisco was the financial hub of the West, the eighth-largest city in the country, and a cosmopolitan cultural center that on April 17, 1906, featured a rousing performance of Carmen with the great tenor Enrico Caruso.

At 5:12 the next morning, a major earthquake turned parts of the city into rubble-and what the quake didn't get a fire created by broken gas mains did. More than 30,000 people lost their lives in San Francisco alone; after three days of fires, 225,000 of the city's 400,000 citizens were homeless.

But that's past; many San Franciscans next week will be commemorating the centennial of their city's worst day while worrying that one even harsher is yet to come. It sounds like an urban legend, but there apparently was a FEMA emergency training session in August 2001 during which participants agreed on the three major disasters most likely to strike the United States: a New York terrorist attack, a massive hurricane hitting New Orleans, and a major California earthquake.

Two of the three, of course, have occurred, and the third is likely: A U.S. Geological Survey working group in 2002 estimated a 62 percent probability of an earthquake measuring 6.7 or greater on the Richter scale in the San Francisco Bay area by 2032. University of California-Davis researchers in the Proceedings of the National Academy of Sciences late in 2005 gave the San Francisco area a 25 percent chance of being struck by a magnitude 7.0 or greater earthquake in the next 20 years, a 50 percent chance in the next 45 years, and a 75 percent chance in the next 80 years.

To interpret such figures, we need to know three things about earthquakes. The first is-no surprise-they are very powerful. A magnitude 5.0 yields as much energy as the Nagasaki atomic bomb. A magnitude 7.0 yields as much energy as the largest thermonuclear weapon ever made. The Pakistan earthquake in 2005 was a 7.6, the 1906 San Francisco earthquake is retrospectively estimated to have been anywhere from a 7.8 to an 8.25 (instruments were imprecise and the Richter scale itself wasn't devised until 1935), and the Indian Ocean earthquake that caused the terrible tsunami of 2004 was a 9.0.

The second is that, as with a bomb, the distance from its epicenter to major cities is crucial in determining the amount of damage. The California earthquake during the 1989 World Series was a 6.9. That would have been devastating had the epicenter been right under San Francisco, but it was 60 miles away. That earthquake killed 63 and created $10 billion of damage, but one with a similar Richter number that struck close to Kobe, Japan, six years later killed 6,500 people and caused at least $150 billion in damage.

Third, we need to understand the Richter scale, because the difference between a Richter 6.7 earthquake (probable in San Francisco by 2032) and a 7.0 (improbable) is far greater than it appears. The Richter scale is logarithmic, which means that the seismic waves of a magnitude 7.0 earthquake are 10 times greater than those of a 6.0, and the energy released (proportional to the square root of the cube of the amplitude) is 31 times greater. Or, to put it simply, a 7.0 is about 11 times more powerful than a 6.7.

This all means that the results of a "major earthquake" in northern California could vary from those resulting from a normal hurricane to those far worse than anything New Orleans saw. The common nightmare scenario has the equivalent of a massive nuclear weapon going off in the San Andreas Fault that runs beneath San Francisco. But another vision of horror has the epicenter of a 6.9-or-greater quake in Oakland or Berkeley; 1 million people live over the Hayward Fault, which runs right underneath the University of California football stadium.

The U.S. Geological Survey pegged the severe Hayward Fault possibility at only 8.5 percent during the next 30 years, so an East Bay politician playing Russian roulette with those odds is holding two six-shooters with a bullet in only one of the cylinders throughout the length of his career: Though "odds" do not restrict God's sovereignty, insurance agents and people generally use them to calculate probabilities (humanly speaking), and the odds of escaping disaster during a particular four-year term look good.

The same odds lead many to go without earthquake insurance. Premiums run $1,000 to $2,000 per year and only 15 percent of California homeowners carry it, with many apparently assuming that FEMA will bail them out if "the big one" does hit.

A close-by 6.9 earthquake would do so much destruction that 360,000 people would most likely be homeless, according to the Association of Bay Area Governments. That figure could be cut substantially if homeowners bolted their houses to their foundations, but since few do, William Lettis of the U.S. Geological Survey working group said simply, "Certain communities in the East Bay have the potential to become ghost towns."

Whether a 6.9 or higher earthquake came in the San Andreas Fault or the Hayward, timing would also be important. If it came during rush hour, thousands of subway riders could die in the BART Transbay Tube. BART subway stations and underground garages would be flooded. The easternmost part of the Bay Bridge, which lost part of its upper deck in the 1989 earthquake, stands in deep mud and would probably collapse. If the earthquake happened during the workday, a half-million commuters would be stranded and homeless in San Francisco for at least several days. Hundreds of unreinforced concrete office buildings would pancake, crushing all within.

San Francisco's city plan rightly places a lot of responsibility on city emergency, police, and fire workers-but most of them cannot afford to live in the city they are sworn to protect, so they often reside across the Bay Bridge. If the earthquake happened when they were off duty, they would most likely have no way to report to work. A San Francisco civil grand jury reported in 2003 that "first responders" were not ready to respond.

The jury also noted that government officials were producing lots of plans but even more confusion. San Francisco's situation was much like that of New Orleans when Katrina hit: The report stated that agencies were updating their plans without distributing new versions to other agencies and the public, so that agencies were likely to act at cross-purposes. Furthermore, guidelines seemed often intentionally vague so that agencies would be protected against lawsuits that would be filed when the agencies failed.

San Francisco in 2006, like New Orleans last year, is ruled by a paperocracy that makes leadership more difficult than it was a century before. When the San Francisco earthquake in 1906 threatened to turn the city into a carnival of looting, Frederick Funston-in charge of the San Francisco army garrison-ordered every available soldier to march to City Hall in full battle dress. Two hours later, two companies presented themselves to the mayor, who then issued an order saying that looters would be shot.

Such a policy would receive condemnation today, and not even Funston could fix the other emergency likely to develop following a Bay Area earthquake: flooding. The levees of northern California are not as famous as those of New Orleans, but they are even more fragile. Some 1,100 miles of levees defend farmland within the Sacramento-San Joaquin Delta, a 1,600-square-mile plain that is up to 30 feet below sea level. It's where San Francisco Bay, the Sacramento River, and four others come together, and the area is so vulnerable that a massive storm or earthquake could collapse the levees and turn the area with its thousands of homes into a lake.

The consequences would reach far beyond the immediate victims: Brackish water rushing in after levee failure would contaminate the drinking water for 22 million Californians and the irrigation supply for 5 million acres of the Central Valley, America's leading agricultural producer.

The levees, originally built by a 19th-century, largely Chinese labor force, are for the most part poorly built earthen dams that already are taxed to their capacity (and sometimes beyond). Southern California has six months of water reserves, but it would take longer than that to remove the saltwater that would rush over collapsed levees.

As in New Orleans, maintenance of the levees is erratic. State and federal agencies maintain about one-third of them, but the rest are under the authority of numerous delta reclamation districts. Meanwhile, builders put up more homes in flood-prone areas; for example, the delta town of Lathrop plans to grow from 12,000 to 80,000 residents over the next quarter-century. There they will be hostages to levees folding under natural pressures-or unnatural ones. A terrorist's well-placed truck bomb could cost many lives and do millions of dollars in damage.

Southern California's water supply could be protected by building a canal to bring water from the Sacramento River to the southern part of the state without having to send it through the readily flooded delta. But Californians in 1982 voted not to spend money on building the Peripheral Canal, since they expected the federal government to pay for it. A quarter of a century later, the pipeline is still not built.

Although northern California receives most of the earthquake attention, researchers at the Southern California Earthquake Center speak of an 80 percent to 90 percent chance that a temblor of 7.0 or greater magnitude will strike Southern California before 2024. Some preparations have happened: Almost all of 2,100 freeway overpasses that need reinforcement have it. Most at risk throughout California are school buildings: A report in 2001 found that of nearly 20,000 brick and concrete school buildings constructed before a 1978 state building code upgrade, 7,500 (78 percent) were "not expected to perform well in future earthquakes," and 1,200 of those buildings were within about a mile of an active fault.

State officials did not divulge names of the specific schools at risk, although school districts were allowed to request that information. Most have not, perhaps in the belief that districts are not legally liable if a disaster occurs and officials are ignorant. Or perhaps politicians are once again playing the percentages: If children are in school seven hours per day over 180 days of the year, if a huge earthquake does occur and buildings collapse, there's only a 1-in-7 chance that children will be buried in the rubble. Gambling with lives in that way seems foolhardy, but many people have short memories and even shorter perspectives on events yet unseen.

Except that we have seen the results of earthquakes on a small scale in southern California-the Northridge quake 12 years ago-and on a gargantuan scale in San Francisco 100 years ago. Novelist Jack London was on the scene, reporting for Collier's magazine: "All the cunning adjustments of a 20th century city had been smashed by the earthquake. The streets were humped into ridges and depressions, and piled with the debris of fallen walls. The steel rails were twisted into perpendicular and horizontal angles. The telephone and telegraph systems were disrupted. And the great water-mains had burst. All the shrewd contrivances and safeguards of man had been thrown out of gear by thirty seconds' twitching of the earth-crust."

London, who knew how to tell a city's story in microcosm, quoted one elderly man: "Today is my birthday. Last night I was worth thirty-thousand dollars. I bought five bottles of wine, some delicate fish and other things for my birthday dinner. I have had no dinner, and all I own are these crutches."