EARTH MOTION MEASUREMENTS. PART I. SEISMIC STUDIES AND CAVITY STUDIES. Preliminary Report
Several parameters were measured of ground motion caused by two deep underground nuclear detonations (Evans and Blanca). Primary measurements included vertical acceleration and velocity in a deep hole over Evans zero, horizontal and vertical acceleration on the mesa surface, and horizontal surface strain. On Evans, only one half of the electronic gage records were useful, and no cork-wire or reed gage data were obtained due to the low yield. Vertical acceleration in the Evans deep hole was one-tenth or less than that predicted. Peak horizontal components of surface acceleration exceeded the vertical, suggesting that much of the blast energy in earth was channeled into rock layers near the surface. Geophone arrival times gave average velocities of 6000 to 7200 ft/sec, consistent with those expected for tuff. On Blanca, limited data were obtained from vertical accelerometers reactivated in the Evans deep hole. Accelerations measured on the mesa surface on Blanca showed vertical maxima consistently larger than the horizontal. Surface strain data indicated that much of the blast energy was refracted or reflected from subsurface layers. Reed gage data indicated that the vertical response spectrum shifts to low frequencies with increasing distance from the burst. (auth)
- Research Organization:
- Stanford Research Inst., Menlo Park, Calif.
- NSA Number:
- NSA-13-017579
- OSTI ID:
- 4243424
- Report Number(s):
- ITR-1702
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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