OPERATION SNOWBALL PROJECT 3.6-EARTH MOTION MEASUREMENTS.
ARMY ENGINEER WATERWAYS EXPERIMENT STATION VICKSBURG MS
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The objectives of Operation Snowball, Project 3.6 were to measure and analyze the earth motions produced by a 500-ton TNT surface burst. This report presents and discusses the measurements obtained from 20 vertically and horizontally oriented velocity gages, 10 vertically oriented accelerometers, 90 mechanical peak acceleration gages, and 4 developmental soil stress gages. These gages were placed on a radial line between 200 and 720 feet from ground zero and at depths from 0.5 to 25 feet. Peak downward acceleration was found to attenuate as ground range to the -3.5 power at 5-foot depths for the three closest in locations ground ranges of 200, 250, and 340 feet where airblast- induced motion predominated. Peak vertical particle velocity attenuated as the -2.5 power of ground range for the 5-foot depth at ground ranges of 200, 250, and 340 feet. Peak horizontal particle velocity showed no attenuation with either increasing ground range or depth to 25 feet. Peak vertical displacements attenuated as the -2.6 power of ground range for the 5-foot depths at ground ranges of 200, 250, and 340 feet. Peak horizontal displacement showed no attenuation with increasing ground range or depth.