SEISMIC EFFECTS FROM A HIGH YIELD NUCLEAR CRATERING EXPERIMENT IN DESERT ALLUVIUM

摘要

SEDAN was a thermonuclear cratering experiment with a yield of about 100 kt detonated at a depth of 660 feet and resulting in a crater of maximum apparent depth of 320 feet and average apparent diameter of about 1200 feet. About 7.5 million cubic yards of earth and rock were displaced. Transitory earth particle motions were on an average twice as large from stations on deep alluvial deposits compared to those on shallow deposits at the same distance. Computed seismic energy was about 2.45 x 1018 ergs, equivalent to a local earthquake magnitude of 4.75. This indicates that .06 percent of the total source energy was converted to seismic energy. Frequency analysis revealed spectral peaks near 1 cps.