SURFACE AND SUBSURFACE STRONG MOTION MEASUREMENTS
Strong motion measurements were made within rock on a vertical radius directly above Evans shot at ranges from 235 feet to the surface at 850 feet and on the mesa surface at ranges out to 12,000 feet from the surface zeros of Tamalpais, Evans, and Blanca shots of Operation Hardtack, Phase II. The complementary surface motion project observed motion of an array of targets in the vicinity of Evans and Blanca surface zeros by means of calibrated motion photography. Vertical radius instrumentation was primarily accelerometers, but stress, strain, and temperature gages were included. Surface motion measurements comprised only vertical and horizontal radial accelerations. Signals from all gages of the vertical array were very weak, and precision suffered accordingly because Evans yielded only about 1 percert of anticipated energy. Acceleration data from the vertical array follow the trends of variation with radial range similar to those indicated by Rainier data: peak accelerations vary inversely with fourth power of range up to the base of the caprock, where the trend inverts and peaks increase toward the surface. Stress, strain and temperature gages yielded no relevart information. Surface accelerations include a few data which represert signals of only a few percent of gage range and are consequently of low precision. Peak accelerations decrease with increased range, but scatter does not permit a clear distinction between suggested R/sup -2/ and R/sup -3/ variation. Photography showed that the ground surface abopve Evans did not move more than 2 inches, the limit of resolution of the camera system. Movemert of targets near Blanca surface zero was defined for a period of greater than 8 seconds after detonation (auth)
- Research Organization:
- Sandia Corp., Albuquerque, N. Mex.; California. Univ., Livermore. Lawrence Radiation Lab.
- NSA Number:
- NSA-13-018225
- OSTI ID:
- 4240008
- Report Number(s):
- ITR-1703
- Country of Publication:
- Country unknown/Code not available
- Language:
- English
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