EARTH VIBRATIONS PROM A NUCLEAR EXPLOSION IN A SALT DOME

摘要

Recorded earth partióle motions in terms of displáce¬meos, velocities, and accelerations were near predictions in the distance range of 1.5 to 603 km for the 5 kt SALMÓN nuclear detonation in a Mississippi salt dome. These motions included measurements from neárby cities and in-dustrial facilities. Scaled earth motions from HE detona-tions of 500 to 4000 Ibs in the unconsolidated shallow sediments were consistently higher than the motions re¬corded from SALMÓN. Asymmetric seismic energy propagation was observed with more efficient propagation to the north and south. Apparent velocities of the first arrivals were:1.458 to 6 km from ground zero, east 2.82 km/sec, south 2.67 km/sec;6 to 100 km, 4.77 km/sec;and 100 to 603 km southwest, 8.5 km/sec. The máximum motions were propagated at near 1.9 km/sec. The horizontal resultant vector for first motion was anomalous for three stations with deviations from a radial path of 36.2o to 66°. Equivalent earthquake magnitude from calculated seismic energies was near 5-1 with a source-seismic energy ratio of 0.47 percent.