The Earthquake Engineering Online Archive

Collapse of the Cypress Street Viaduct as a result of the Loma Prieta earthquake

Nims, Douglas K.; Miranda, Eduardo; Aiken, Ian D.; Whittaker, Andrew S.; Bertero, Vitelmo V.

UCB/EERC-89/16, Earthquake Engineering Research Center, University of California, Berkeley, 1989-11, 85 pages (705.326/1989L/C64)

At 5:04 p.m. on Oct. 17, 1989, a surface wave magnitude 7.1 earthquake centered in the Santa Cruz Mountains severely damaged structures, buildings, freeways, and bridges in the coastal zone of northern California bounded in the south by the city of Monterey and in the north by the cities of San Francisco and Oakland. The majority of the approximately 70 deaths resulting from the earthquake were caused by the collapse of the Cypress Street Viaduct section of Interstate 880. This report describes the observations of the reconnaissance teams from the Earthquake Engineering Research Center of the Univ. of California at Berkeley of the Cypress Street Viaduct. Analyses and discussions, based on a bent-by-bent survey, are presented along with sketches and photographs that describe the structure and its damage. Results from ambient vibration tests of a section of the viaduct that was minimally damaged by the earthquake are also given.

Available online: http://nisee.berkeley.edu/documents/EERC/EERC-89-16.pdf (6 MB)