Wednesday, August 29, 2007

How well prepared is San Francisco for a large earthquake?

The San Francisco earthquake of 1906 killed at least 3,000 people. It was of magnitude 7.9. 200,000 people were left homeless. Fires that raged through San Francisco in the wake of the earthquake destroyed 28,000 buildings.

On the basis of research conducted since the 1989 Loma Prieta earthquake, U.S. Geological Survey (USGS) and other scientists conclude that there is a 70% probability of at least one magnitude 6.7 or greater quake, capable of causing widespread damage, striking the San Francisco Bay region before 2030. Major quakes may occur in any part of this rapidly growing region. This emphasizes the urgency for all communities in the Bay region to continue preparing for earthquakes...

San Francisco is not prepared for an earthquake of magnitude 7.9. Since 1906, the population of the Bay Area has grown from about 700,000 to about 7 million people . Building standards are higher now. However many buildings are still not adequately reinforced. Some hospitals such as The San Francisco General would be at risk as would many schools. Whilst efforts have been made to strengthen some bridges- to withstand earthquakes- grave doubts must exist until these bridges are tested by a powerful quake.
A major upgrade of the water system will not be completed before 2015. If a massive earthquake were to strike now huge damage would be inflicted on water networks.

If an earthquake on the scale of the 1906 quake were to occur it is estimated that approximately 40,000 office buildings would be destroyed in areas concentrated along the fault zones of San Francisco, San Mateo, Santa Clara County, Alameda and Oakland. The Association of Bay Area Governments has estimated that more than 150,000 uninhabitable residences will occur in a M7.9 repeat of the 1906 earthquake or a M6.9 rupture of the entire Hayward fault. The East Bay I-880 corridor along the Hayward fault would experience the most proportional property damage of the entire Bay area.
The worst case scenario for the Bay Area, is estimated to result in about 5800 fatalities if it strikes during working hours. Some how I think that these figures are an underestimate of the likely number of deaths.
San Francisco’s financial district, is also vulnerable to large earthquakes on both sides of the Bay.
It is estimated that property losses could be up to 300 billion dollars.

In summary many bridges, hospitals, schools, and buildings have not been adequately upgraded
If the buildings are destroyed, their gas and water lines could be seriously damaged, making the likelihood of fire very substantial. San Francisco is not adequately prepared.

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