Loma Prieta earthquake (1989)
The 6.9-magnitude Loma Prieta earthquake collapsed the Cypress Street Viaduct in Oakland and damaged the San Francisco-Oakland Bay Bridge, closing it for a month. The quake killed 63 people, many in the Cypress collapse.
Bay Bridge closed for a month, forcing commuters onto BART and other routes.
Led to a major retrofit program for Bay Area bridges and freeways, including the eventual replacement of the Bay Bridge east span.
Showed how dependent the Bay Area is on its freeway and bridge network, and how disruptive closures can be.
