ANALYSES OF GROUND MOTIONS AT UNION BAY, SEATTLE, DURING EARTHQUAKES AND DISTANT NUCLEAR BLASTS

THE CITY OF SEATTLE AND THE STATE OF WASHINGTON COOPERATED IN THE INSTALLATION OF A SEISMOGRAPH SYSTEM AT UNION BAY IN SEATTLE, WASHINGTON, THIS SYSTEM WAS INSTALLED TO RECORD SEISMIC MOTIONS IN THE VARIOUS SOIL STRATA UNDERLYING UNION BAY FOR THE PURPOSE OF COLLECTING DATA FOR USE IN THE SEISMIC DESIGN OF THE THOMSON WAY CROSSING, A PROPOSED SIX-LANE HIGHWAY TUNNEL UNDERPASSING THE WASHINGTON SHIP CANAL. ACCELERATION RECORDS WERE OBTAINED AT THREE DEPTHS DURING A MILD EARTHQUKE IN 1967 AND SEVERAL UNDERGROUND NUCLEAR BLASTS THAT WERE SHOT AT NEVADA TEST SITES FROM 1966 TO 1968. RECORDINGS WERE MADE BY INSTRUMENTS PLACED IN PEAT 10 FEET BELOW THE GROUND, AND CLAY 61 FEET BELOW THE GROUND SURFACE AND IN GLACIAL TILL, 102 FEET BELOW THE GROUND SURFACE. USING AN EQUIVALENT LINEAR VARIABLE DAMPING LUMP TYPE AND MASS SALUTION, ENCORPORATING STRAIN-DEPENDENT MATERIAL PROPERTIES FOR THE PEAT AND CLAY LAYERS, THE MOTIONS THROUGHOUT THE DEPOSITS WERE COMPUTED. THE RECORDED ACCELERATIONS IN THE GLACIAL TILL WERE USED AS INPUT BASE MOTION. COMPARISONS OF THE TIME HISTORIES OF ACCELERATIONS, MAXIMUM ACCELERATIONS AND SPECTRAL VALUES OF THE MOTIONS RECORDED DURING THE EARTHQUAKE WITH THE CORRESPONDING COMPUTED MOTIONS INDICATED A HIGH DEGREE OF AGREEMENT. THE MAXIMUM ACCELERATIONS RECORDED DURING THE DISTANT NUCLEAR BLAST EVENTS ALSO COMPARED WELL WITH THE COMPUTED ACCELERATIONS.

  • Supplemental Notes:
    • 10 Pp, 12 FIG, 3 TAB, 6 REF
  • Corporate Authors:

    University of California, Berkeley

    Berkeley, CA  United States  94720
  • Authors:
    • Seed, H B
    • Idriss, I M
  • Publication Date: 0

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Filing Info

  • Accession Number: 00235733
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Jul 21 1970 12:00AM