Column failure at an overpass (Foothills Freeway crossing Foothills Boulevard) as a result of the San Fernando earthquake of 1971. This slide shows failures of three of the spirally- wrapped columns that provided the central support of this overpass. The third column shows relatively minor damage. Failures may have resulted from a combination of vertical and horizontal acceleration. It appears that the bridge deck may have rotated due to the ground motion.

Image Credit: E.V. Leyendecker. U.S. Geological Survey