OSMS 86-07

by A.F. Shakal, M.J. Huang, D.L. Parke and R. Linares

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Strong-motion records were recovered from nine strong motion accelerographs of the El Salvador Geotechnical Investigation Center Strong Motion Network (ESCIGSMN) following the damaging San Salvador earthquake of October 10, 1986. The strong motion stations were installed in San Salvador by the Geotechnical Investigation Center (CIG) following the 1965 San Salvador earthquake. During the October 10, 1986 earthquake, relatively large accelerations (in excess of 70% g) were recorded at close-in distances from an earthquake of only moderate magnitude (5.4 Ms). Because of the importance of these data not only to El Salvador but also to California, where close-in strong motion data are very limited, the California Strong Motion Instrumentation Program digitized and processed these data for distribution to engineers, seismologists and others concerned with the seismic safety problem. The first part of this report includes a short overview of the earthquake characteristics, key aspects of the data (station distances, peak acceleration, etc.), and a description of the accelerogram digitization procedures. Reproductions of the film accelerograms are included in the Appendix A. In Appendix B the results of the accelerogram digitization and processing are presented through a series of plots of the acceleration, velocity and displacement, and the absolute acceleration and relative velocity response spectra.