The Loma Prieta earthquake occurred in San Francisco on October 17, 1989.  It was a magnitude 6.9 on the moment magnitude scale.  The death toll was 63 and the damage cost an estimated six billion dollars (Stoffer, 2005).  The damage exposed poor building standards and poor location choice. The Marina District in San Francisco was built on fill made of sand, dirt and rubble, which underwent severe liquefaction and many buildings collapsed (Virtual Museum of the City of San Francisco, 2009).  The Cypress Viaduct was built using non-ductile reinforced concrete and was also built on marshland which underwent liquefaction during the shaking.

The Loma Prieta earthquake also revealed a number of success stories in disaster mitigation.  The main success was Candlestick Park which had recently undergone a seismic strengthening project and stood strong during the earthquake, sparing thousands of lives (Housner, 1990).

As a result of the major structural failures, San Francisco has been taking steps for mitigation, rebuilding, retrofitting old buildings, and strengthening structures in light of stricter building codes.  The Loma Prieta earthquake revealed that buildings built before 1971 were easily collapsed (Nigg, et al, 1998).  The California Earthquake Authority (CEA) plans to institute a state-wide residential seismic retrofit program.  This program will offer homeowners the opportunity to take action to make their houses more seismically stable with the aid of a government rebate.  Specialized training was given to contractors, engineers, and inspectors specifically towards seismic engineering (Parrish, et al., 2009).  Base isolation, which isolates the building’s attachment to the ground from the superstructure above the ground, was installed in San Francisco International Airport and San Francisco’s city hall, the first and second largest base isolated structures in the world respectively (SFGov, 2009).

The most vital mitigation that is taking place is being undertaken by the utility companies of San Francisco. Many companies are taking steps to safeguard their water, electricity, transportation, and communication systems, many of which were lost during Loma Prieta.  California’s highway company, Caltrans, is strengthening bay bridges, freeway sections, and overpasses, PG&E is working to be sure that power and gas systems will not fail during a quake, and there has been an upgrade to the emergency water system (Bakun, 1995).  Clearly, many mitigation and retrofitting steps have been taken as a result of the Loma Prieta earthquake.

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