RECORDING AND INTERPRETING STRONG EARTHQUAKE ACCELEROGRAMS

This paper examines the considerations which are important for layout of strong motion accelerograph stations and arrays, and for use and interpretation of strong motion accelero-graph records. The major long range decisions include use of the data, which determines the geometrical arrangement and number of the instruments, and the procedures to convert the data to a digital format for computer processing. Typical purposes for individual and for arrays of stations are: ۱) to study the earthquake source mechanism",۴۹, ۲) to study wave propagation and attenuation near (within ۱۰۰ - ۲۰۰ km) the source and ۳) to study building responsea۱,۳۲,۷۲. Most of these problems focus on the similar amplitude range (۱۰-۳g to ۱۰g) and frequency range (۰.۱ Hz to ۳۰ Hz). Longer period, near source, information may be needed in the future for source mechanisms of larger events. To study wave propagation in detail, instruments need to be spaced more closely than the wavelength of the waves so that clusters of instruments may be called for. Digitization may be accomplished either at the recorder or in the laboratory. It was believed for many years that field digitization speeds the processing, but modern laboratory digitization۲۹ places the sophistication needed under more controlled conditions and thus increases the reliability of the overall system