Side view of the Cypress section of Interstate 880 which collapsed as a result of the 1989 Loma Prieta (California) earthquake. Note the failed column support (buttress) in the center of the photo. The upper deck of the double deck structure dropped almost vertically onto the lower deck along a one-mile section of the freeway. Columns supporting the upper deck were thrown transverse to the longitudinal axis of the roadway. Some columns sheared off at the hinge at the bottom of the upper column; some remained attached to the upper deck. Other columns were found completely intact on the ground. Fifty-one spans of this structure were involved in the collapse which killed forty-one motorists.

Image Credit: Wilshire. U.S. Geological Survey