Loma Prieta earthquake

The Loma Prieta earthquake occurred on October 17, 1989 in the greater San Francisco Bay Area in California at 5:04 pm local time and measured 7.1 on the Richter magnitude scale (6.9 on the Moment magnitude scale). The earthquake lasted for fifteen seconds. Its epicenter was at 37.04° N latitude, 121.88° W longitude near Loma Prieta Peak in the Santa Cruz Mountains, about ten miles (16 km) northeast of the town of Santa Cruz, California, in the Forest of Nisene Marks State Park.

Transportation Effects

The Loma Prieta earthquake irrevocably changed the San Francisco Bay Area's transportation landscape. Not only did the quake force seismic retrofitting of all San Francisco Bay Area bridges, it caused enough damage that some parts of the region's freeway system had to be demolished. In some cases, the freeways in question had never been completed, terminating in mid-air; in that regard, the quake provided the impetus to deal with regional transportation problems that had gone largely unsolved for decades.

Related Topics:
Seismic retrofitting - San Francisco Bay

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• San Francisco-Oakland Bay Bridge, Interstate 80: The Bay Bridge was repaired and reopened to traffic in just one month's time. However, the earthquake made it clear that the Bay Bridge, like many of California's toll bridges, required major repair or replacement, for long-term viability and safety. Construction on a replacement for the eastern span would not begin, however, until January 29, 2002. As of 2005, news accounts estimate that the project will not be completed by 2011 due to the California budget crisis. (For discussion, see also San Francisco-Oakland Bay Bridge).
• Cypress Structure/Nimitz Freeway, Interstate 880: The double-decked "Cypress Structure", Interstate 880, was demolished soon after the earthquake, and was not rebuilt until July 1997. The rebuilt highway was no longer a double-decker structure, and it was constructed around the outskirts of West Oakland, rather than bisecting it, as the Cypress structure did.
• Embarcadero Freeway, California State Route 480: The earthquake forced the closure and demolition of San Francisco's largely unloved Embarcadero Freeway (Interstate 480); this demolition opened up San Francisco's Embarcadero waterfront to new development. The concrete freeway, which ran right along San Francisco's waterfront and had never been completed, was replaced with a ground-level boulevard.
• Southern Freeway, Interstate 280: Seismic damage also forced the long-term closure of Interstate 280 in San Francisco (north of US-101), another concrete freeway which had never been completed to its originally planned route. The highway remained closed for seven years, with its repair facing numerous delays.
• Central Freeway, U.S. Highway 101: San Francisco's Central Freeway (part of US 101) was another concrete double-deck structure which faced demolition due to safety concerns. Originally terminating at Franklin Street near San Francisco's Civic Center, the section past Fell Street was demolished first, then later the section between Mission and Fell Streets. A new section connecting the freeway from Mission Street to Market Street was completed in September of 2005, ending at a ground-level boulevard along Octavia Street, carrying traffic to both Fell and Franklin Streets.
• Highway 17, California State Route 17: The mountain highway was closed for about 1 month due to landslide. The highway is very close to the epicenter and it crosses the San Andreas Fault.