Thursday, October 15, 2009

20 Years After Loma Prieta Earthquake, Is San Francisco Prepared For 'The Big One?'

On October 17, 1989, the Greater Bay Area Was Slammed By Its Strongest Tremor Since 1906 -- a 6.9-Magnitude Shaker That Killed 63 People, Injured Over 3,700 Others and Wreaked Over $6 Billion in Damage; Two Decades Later, Many Public Structures have Been Braced, But Most Homes Remain Vulnerable

The Cypress Structure collapse

Officials of the California Department of Transportation survey the wreckage of the double-decked Cypress Freeway in Oakland on October 20, 1989, three days after a 6.9-magnitude earthquake -- the strongest since 1906 -- struck the San Francisco Bay Area during the height of the evening commute, causing the upper deck of the freeway -- as well as a section of the landmark Bay Bridge -- to collapse. Dozens of cars on the lower deck of the freeway were crushed, killing 42 people and injuring scores of others. Twenty years later, a newly-released survey found that while many public structures have bee retrofitted to withstand the next major quake, thousands of private homes remain highly vulnerable. (Archive photo courtesy U.S. Geological Survey)

(Posted 5:00 a.m. EDT Thursday, October 15, 2009)

This week marks the 20th anniversary of the San Francisco Bay Area's worst natural disaster since the Great Earthquake and Fire of 1906: The Loma Prieta Earthquake, which killed 69 people and caused over $6 billion in damage. At the time, I was a copy editor for a San Francisco newspaper and lived across the bay in Berkeley. I was working later than usual when the quake struck at 5:04 p.m., right at the height of the evening commute. I consider myself lucky to be alive, for had I not had to work late that day -- and had there not been 60,000-plus fans at Candlestick Park for Game 3 of the 1989 World Series between the San Francisco Giants and the Oakland A's -- the number of fatalities from the collapse of part of the Bay Bridge and of the Cypress Freeway in Oakland would have been much greater. In this special commemorative report, we take a look back at the disaster and look ahead to see what is being done to prepare for the next one.


It was a warm autumn evening on October 17, 1989, a Tuesday. More than 60,000 die-hard baseball fans packed into Candlestick Park in San Francisco for Game 3 of the "Battle of the Bay" World Series between the Oakland Athletics and the San Francisco Giants. Hundreds of thousands of commuters were on their way home from work -- many with their car radios tuned in to the pre-game show.

Millions more throughout the Bay Area and across the country had turned on their TVs to watch ABC's coverage of the game. It was just past five o'clock -- eight o'clock on the East Coast -- as ABC announcers Al Michaels and Tim McCarver were discussing highlights of Games 1 and 2 in Oakland, both of which were won by the A's.

Suddenly, just after the Candlestick scoreboard clock clicked to 5:04 p.m., the announcers' booth -- along with the entire stadium -- began shaking violently. Viewers, who were watching a video of the previous game, saw the picture begin to flicker off and on. Many in the stadium crowd began to scream. Michaels then shouted, "I'll tell you what, folks, we're having an earth--"


"--Quake!" never made it on the air. The power went out, cutting off ABC's live feed before Michaels could finish his sentence.


The greater San Francisco Bay Area had just been hit by a tsunami of roiling soil and rock generated by a gargantuan explosion 11 miles underground -- as if seven 100-megaton thermonuclear bombs had gone off simultaneously -- some 70 miles to the south at Loma Prieta in the Santa Cruz Mountains.

By the time the shaking stopped some 15 terrifying seconds later, a huge swath of Northern California from the Monterey Bay north to Sacramento and from the Pacific Coast east to Nevada had been turned -- both figuratively and literally -- upside down.

Sixty-three people were killed and more than 3,700 others were injured in the quake, which measured 6.9 on the Richter scale and was the most powerful temblor to strike the Bay Area since the Great Earthquake of 1906, which reduced all of downtown San Francisco to a pile of burning rubble.

Forty-two of those 63 deaths occurred in Oakland, when the upper deck of the double-decked Cypress Freeway collapsed onto the lower deck, crushing dozens of vehicles at the height of the homebound commute. The quake also caused a section of the inbound upper deck of the famed Bay Bridge to collapse onto the outbound lower deck. Several cars on the upper deck plunged into the gap, killing at least one driver and injuring a dozen others.

Were it not for the World Series game at Candlestick Park, traffic would have been much heavier on both the Bay Bridge and the Cypress Freeway and the death toll would certainly have been much higher.

Television viewers across the country soon got to watch an eerie repeat of history unfold live, as an entire block of the city's swanky Marina District burned to the ground as a result of ruptured natural-gas mains, but unlike the 1906 disaster, the local utility company, Pacific Gas & Electric, was able to quickly shut off the gas and the water mains stayed intact, enabling a small army of firefighters and volunteers to prevent the blaze from spreading.

Nevertheless, for the next 18 to 24 hours after the quake struck, all of San Francisco and a huge swath of the greater Bay Area had to live without electricity, as the temblor knocked out much of PG&E's power distribution network, forcing the Bay Area Rapid Transit system to shut down and most of the area's hospitals, police and fire stations and radio and TV stations to fire up their emergency generators.

Yet throughout the disaster, the Bay Area dis not descend into total chaos. By the millions, residents rallied to rescue the trapped and injured, comfort the bereaved who lost loved ones and bring the region back to its feet.

Ten days after the quake, the World Series resumed at Candlestick Park, with the 62,000 fans paying tribute to the region's police officers, firefighters, paramedics and other first-responders with a five-minute standing ovation in an emotional pregame ceremony that included a moment of silence for the 63 people who lost their lives in the temblor, followed by the singing en masse of "San Francisco," the song immortalized in the 1936 film about the 1906 disaster.

And by the way, the A's beat the Giants to complete a four-game sweep of the Series.


Two decades later, a lot has changed in and around San Francisco and the surrounding Bay Area. Many schools, highways and other public buildings have been retrofitted to withstand another major quake of up to 8 on the Richter scale.

Other structures -- including the Embarcadero Freeway along the San Francisco waterfront and the Central Freeway which cut into the city's Hayes Valley neighborhood -- were torn down after structural engineers found they were unsafe. The destroyed Cypress Freeway in Oakland is now a broad, tree-lined boulevard renamed in honor of former South African President Nelson Mandela.

But thousands of private homes and apartment buildings -- particularly those built of unreinforced brick and masonry -- remain vulnerable. Scientists warn that there is a more than 60 percent probability of a major earthquake of magnitude 7 or greater striking the region in the next 30 years.

Some of the most vulnerable buildings -- built decades before state building codes were upgraded for greater seismic safety in the 1970s -- are located in San Francisco's densely populated Chinatown and Tenderloin neighborhoods. Others, located in the affluent Marina District and the bohemian South of Market area, are built on landfill reclaimed from the bay that can liquefy during a major quake, causing buildings to collapse.

If those buildings are not retrofitted, hundreds of residents in those areas could be killed and thousands more displaced if the long-dreaded "big one" hits -- a quake equal to or greater than the 1906 shaker, geologists warn.


Hospitals in the region remain at high risk, having fallen behind state-imposed deadlines to retrofit their buildings because of the high cost. In San Francisco proper, only now are hospitals undergoing seismic upgrades, with most of the work not expected to be completed until 2015, according to the San Francisco Chronicle.

The 1906 earthquake struck before the Richter scale was invented, but is estimated to have been a magnitude 7.9 (For decades, it was believed that the monster temblor was an 8.3, but in a report released on the 100th anniversary of the disaster in 2006, the U.S. Geological Survey re-examined the amount of slippage on the San Andreas Fault and recalculated the earthquake at 7.9).

"We have been retrofitting public infrastructure, but in the Bay Area and California, we have done a miserable job of retrofitting where we live," Peter Yanev, a seismic engineer and author who sits on engineering advisory councils at the University of California at Berkeley and the Massachusetts Institute of Technology, told the Chronicle. "In San Francisco, there are hundreds and hundreds of buildings that are not retrofitted, and they are a risk to people's lives."


The region is streaked by at least four major earthquake faults: The 1,700-mile San Andreas -- the most famous and feared fault in California -- on which the Loma Prieta quake was centered; the Hayward Fault, on the east shore of San Francisco Bay, along which lie the densely populated cities of Oakland, Berkeley, Richmond and Hayward; the Calaveras Fault, which runs through the hills between the Bay Area and the Central Valley; and the Rogers Creek Fault, which is really a northern extension of the Hayward, located north of San Pablo Bay.

There are at least a half-dozen smaller faults that bisect the Bay Area as well. Next to the San Andreas, the Hayward Fault poses the greatest risk of generating a major quake -- and causing the greatest amount of death and destruction. Not only does the fault run through Oakland and Berkeley, but the University of California's 60,000-seat football stadium in Berkeley lies directly on the fault and the BART system's Concord Tunnel cuts directly through it.

As the Bay Area prepared to mark Saturday's anniversary of the Loma Prieta quake, its residents received a another reminder of just how unstable the ground beneath them is: a 3.7-magnitude earthquake struck just south of the San Francisco suburb of Pleasanton shortly before 8:30 p.m. Tuesday night, followed by two smaller temblors in the same area.

The U.S. Geological Survey reported that the first quake was centered three miles south of Pleasanton. It was reported as having a relatively shallow depth of five miles.

About two hours later, two smaller earthquakes struck, each a magnitude 2.1 on the Richter scale. The first, at 11:18 p.m., had a depth of about 5.2 miles and was centered about five miles north-northeast of the town of Sunol. The second, at 11:27 p.m., had a depth of about 4.3 miles and was centered about eight miles south-southeast of Sunol.

There were no reports of injuries or damage.

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Volume IV, Number 78
Copyright 2009,Skeeter Sanders. All rights reserved.


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