The San Francisco area earthquake of 1989 and implications for the Greater Vancouver area

Abstract

The earthquake that hit the San Francisco area on October 17, 1989, is reviewed with respect to damage to buildings, transportation facilities, and services. The San Francisco experience underlines that soil conditions and inadequate structural integrity are the two most important factors in the seismic risk to a building and its inhabitants. This earthquake is used as a model for the damage prediction in the Greater Vancouver area from a "design earthquake" that is implied in the National Building Code of Canada. In comparable housing density the expected damage would be somewhat greater than that observed in the San Francisco region in October 1989 because of differences in amplitude of ground motions and building design standards. This study is seen as a first step in the detailed assessment of damage potentials for the Vancouver region, or other similar metropolitan areas. Potential shortcomings in the 1985 National Building Code of Canada were identified in the seismic requirements for non-engineered buildings (Part 9) concerning lateral bracing, beam splice ties over supports, and anchorage and reinforcing of chimneys. Key words: earthquake damage, building code, damage prediction.