New study of impact of 1906 sized earthquake to be released

By Jason Bennert, Bay City News Service

April 9, 2006

If a major earthquake as strong as the 1906 San Francisco Earthquake struck the Bay Area today it could cause approximately 5,800 deaths and billions of dollars in damage and economic impact, according to researchers.

A 2003 study overseen by the U.S. Geological Survey concluded that there is a 62 percent probability that a magnitude 6.7 or greater earthquake will strike the Bay Area by 2032.

"A repeat of the 1906 magnitude 7.9 earthquake, the worst case scenario for the Bay Area, is estimated to result in about 5,800 fatalities if it strikes during working hours. This estimate is comparable to the approximately 6,000 deaths caused by the 1995 M6.9 Kobe earthquake that occurred in the afternoon directly beneath an urban area with a population of 1.52 million people," according to the study Earthquake Probabilities in the San Francisco Bay Region: 2003-2032.

The 1995 Kobe, Japan earthquake caused an estimated $147 billion in direct losses in addition to 6,000 deaths. In comparison, the last major earthquake in California, the 6.7 magnitude 1994 Northridge quake, caused approximately $20 billion in direct losses and 20 people were killed, according to the study.

The USGS plans to release an updated study that specifically estimates what the impact of a 1906-sized earthquake would be on the Bay Area on April 17, the day before the 100th Anniversary of the Great San Francisco Earthquake, according to Mary Lou Zoback, the co-coordinator of the USGS Earthquake Hazards Program in Northern California.

The last major Bay Area earthquake, the 6.9 magnitude Loma Prieta earthquake that interrupted the 1989 World Series, caused major damage from Santa Cruz to Oakland including 63 deaths and more than 13,000 injuries. It destroyed 366 businesses and more than 1,000 homes. In addition, approximately 3,500 businesses and 23,000 homes were damaged. The total economic loss from the earthquake was valued at more than $16 billion by the Federal Deposit Insurance Corporation in an analysis issued last year following Hurricane Katrina.

If a 1906-sized temblor struck the Bay Area today it would likely affect as wide an area as the Loma Prieta earthquake, according to USGS geophysicist Brad Aagaard.

"We want to emphasize that a large earthquake such as 1906 is not just a San Francisco quake, but a Northern California earthquake. Earthquakes greater than magnitude 7 are going to cause intense shaking over a large area - everyone needs to be prepared," Aagaard said last month at the unveiling of a study of how hard the ground shook in 1906.

The impact of the 1906 quake went far beyond the loss of life, physical and economic damage, according to two Southern California economists. It led to the Panic of 1907 and a fundamental change in the U.S. banking system.

Economists Kerry Odell, a professor at Scripps College, and Marc Weidenmier, a professor at Claremont McKenna College, in a 2001 research paper, titled Real Shock, Monetary Aftershock: The San Francisco Earthquake and the Panic of 1907, linked the 1906 quake to the 1913 establishment of the Federal Reserve banking system.

"The quake's impact manifested itself in international gold flows, as British insurance companies paid their San Francisco claims out of home funds in the fall of 1906. The capital outflow threatened the fixed sterling-dollar exchange rate, leading the Bank of England to raise interest rates and discriminate against American finance bills. The resulting contraction pushed the United States into recession, setting the stage for the 1907 Panic and the founding of the Fed," according to Odell and Weidenmier's paper.

The 1906 quake and subsequent fire in San Francisco caused an estimated $350-$500 million in damage, approximately 1.3 to 1.8 percent of the U.S. Gross Domestic Product in 1906. In comparison, the damage from the September 11 terrorist attacks that destroyed the World Trade Center was less than 1 percent of the U.S. GDP, according to the research paper.

The Odell-Weidenmier paper is available on the World Wide Web at http://econ.claremontmckenna.edu/papers/2001-07.pdf.

The USGS 2003 study is available at http://pubs.usgs.gov/of/2003/of03-214/.

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