The Whittier Narrows, California earthquake of October 1, 1987: Preliminary assessment of strong ground motion records

More than 250 strong-motion accelerograph stations were triggered by the Whittier Narrows, California, earthquake of 1 October 1987. Considering the number of multichannel structural stations in the area of strong shaking, this set of records is one of the more significant in history. Three networks, operated by the U.S. Geological Survey, the California Division of Mines and Geology, and the University of Southern California produced the majority of the records. The excellent performance of the instruments in these and the smaller arrays is attributable to the quality of the maintenance programs and their funding and personnel requirements. Readiness for a magnitude 8 event is directly related to these maintenance programs. Prior to computer analysis of the analog film records, a number of important structural resonant modes can be identified, and frequencies and simple mode shapes have been scaled. The structural records form a basic performance measurement for comparison with larger earthquake response in the future.