1989 Loma Prieta earthquake larger loss of life, as several of the Bay Area's major transportation structures suffered catastrophic failures. The collapse of a section of the double-deck Nimitz Freeway in Oakland was the site of the largest number of casualties for the event, but the collapse of man-made structures and other related accidents contributed to casualties occurring in San Francisco, Los Altos, and Santa Cruz. The history of earthquake investigations in California has been largely focused on the San Andreas Fault System, due to its strong influence in the state as the boundary between the Pacific Plate and the North American Plate; it
1989 Loma Prieta earthquake removed and replaced the collapsed section, and re-opened the bridge on November 18. The worst disaster of the earthquake was the collapse of the two-level Cypress Street Viaduct of Interstate 880 in West Oakland. The failure of a section of the viaduct, also known as the "Cypress Structure" and the "Cypress Freeway", killed 42 and injured many more. Built in the late 1950s, the Cypress Street Viaduct, a stretch of Interstate 880, was a double-deck freeway section made of nonductile reinforced concrete that was constructed above and astride Cypress Street in Oakland. Roughly half of the land the Cypress Viaduct