Commemoration Marks 140th Anniversary of San Francisco Quake
History Indicates Imminent Earthquake in San Francisco Bay's FutureJames Lienkaemter, a U.S. Geological Survey geophysicist, discusses the implication of the regular intervals of 12 Hayward Fault earthquakes over the past 1,900 years and how scientists were able to obtain that data.
Wednesday, October 22, 2008
Category: News > City
Tuesday marked the 140th anniversary of the powerful earthquake that devastated several East Bay towns and was ranked as one of the worst in California history.
The magnitude 6.8 quake, known as the "Great San Francisco Quake" for some time, killed an estimated 30 people and caused significant property damage. It was strongest in cities along the southern section of the Hayward Fault.
A public commemoration of the quake was held yesterday morning at Mission San Jose in Fremont, said Tom Brocher, the U.S. Geological Survey coordinator for Earthquake Hazard Investigations in Northern California.
Today, a similar quake could damage about 10 percent of total property in the Bay Area and 30 to 40 percent of property along the fault, he said. The cost of damages could exceed $120 billion.
There are 2.4 million people currently living in Alameda County, far more than the 24,000 who were living there in 1868.
"The Hayward Fault is one of the most urbanized faults in the Bay Area and perhaps the nation," Brocher said. "An earthquake that size would be right in people's backyards."
Brocher said there is a one in three chance that in the next 30 years the fault will produce an earthquake with a magnitude of 6.7 or greater. He said the past five earthquakes along the fault have occurred at an average interval of about 140 years.
If an earthquake of the same magnitude were to happen today, Brocher said, the damage in Berkeley would probably be limited to older buildings which do not meet current building codes.
In 1997, Chancellor Robert Berdahl implemented a plan called the Seismic Action Plan for Facilities Enhancement and Renewal to assess the seismic safety performance of the campus's structures, said Christine Shaff, communications manager for UC Berkeley Facility Services.
A survey conducted by structural engineering firms concluded that 27 percent of the campus's square footage needed upgrading. Of the campus's buildings, 57 were rated "poor" or "very poor," including Evans Hall, Eshleman Hall and the observation level of Sather Tower.
The total cost of the plan could exceed $1.2 billion in costs, spanning a 20 to 30 year time frame. Since the plan was initiated, $400 million has been spent on seismic retrofitting, including on roughly 23 buildings.
Shaff said that in several recent instances, the campus decided to replace instead of retrofit buildings.
"The old Stanley Hall (was replaced with) a new facility that was not only seismically stronger, but had facilities that better support our modern teaching and research needs," she said.
Some other structures that have been retrofitted include Barrows Hall, Barker Hall and Doe Library. There are currently plans to retrofit Memorial Stadium and Martin Luther King Jr. Student Union, among other sites.
Councilmember Gordon Wozniak said that Berkeley is fairly well prepared for another 1868 quake because of its high number of seismically retrofitted structures.
He said that nearly two-thirds of homes in Berkeley have been retrofitted. This is partly due to the Seismic Retrofit Refund Program, which refunds one-third of Berkeley residents' transfer tax for voluntary eligible seismic upgrades to residential property.
He said the city has spent roughly $50 million retrofitting fire stations, city office buildings and the Downtown library as well as $100 million on various school buildings.
"We have invested huge sums of money to try to prepare for the eventual earthquake," he said.
Wozniak listed Berkeley's Soft Story Ordinance as an in-progress seismic project, aimed at improving soft story buildings that house approximately 4,000 people. Soft story buildings contain underground garages supported by pillars that are very susceptible to the force of an earthquake.
Wozniak said Berkeley will continue its efforts to improve its defenses against a repeat of the 1868 quake.
"We have to continue making those kinds of investments in the future," he said. "The estimates (of exactly when the earthquake will occur) are still uncertain. There may be time to do more."
Contact Emily Grospe at [email protected]
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