First Interim Set of CSMIP Processed Strong-Motion Records from the Sierra Madre, California Earthquake of 28 June 1991

OSMS 92-01

by R.B. Darragh, T.Q. Cao, C.H. Cramer and A.F. Shakal

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Strong-motion records were recovered from 94 stations of the California Strong Motion Instrumentation Program (CSMIP) following the Sierra Madre earthquake of June 28, 1991 which occurred under the San Gabriel Mountains, approximately 20 km northeast of downtown Pasadena. The records from these 94 stations are presented in the CSMIP data report on the earthquake (see Reference). Digitization and processing of the records recovered by CSMIP started after the data report was completed and is continuing. The results of digitizing and processing of the first interim set of records from 10 stations has been completed and the results are presented in this report. These 10 stations include 6 ground response, 3 instrumented buildings and 1 lifeline structure.

The plots for these records are arranged as follows:

      o Ground-Response Stations:
            1. Mt. Wilson - Caltech Seismic Station
            2. Altadena - Eaton Canyon Park
            3. San Marino - Southwestern Academy
            4. Los Angeles - Obregon Park
            5. Tarzana - Cedar Hill Nursery
            6. Vasquez Rocks Park
      o Instrumented Buildings:
            7. Burbank - 6-story Commercial Bldg. (13 channels)
            8. Burbank - 10-story Residential Bldg. (16 channels)
            9. Pasadena - 6-story Office Bldg. (16 channels)
      o Instrumented Lifeline Structure:
            10. Cogswell Dam (9 channels)

Information on the earthquake and recording stations are given in the reference. Details on accelerogram digitizing and processing will be presented in. the forthcoming final CSMIP processed data report.