FROZEN EARTH MATERIALS AS SEISMIC DECOUPLING MEDIUMS.

: The SOC computer code, designed to calculate the effects of detonations of contained explosions on the surrounding medium, was used to calculate a source function called the reduced displacement potential. The input to the code was an experimentally determined equation of state for each of the following frozen earth materials (at -10 deg C): dry and ice- saturated sand, partially and fully ice-saturated glacial till, and ice. The reduced displaced potential was convolved with the response of the Benioff seismometer and appropriate attenuation operators. The first half-cycle displacement amplitudes at 300 and 500 km were compared to those obtained from particle velocity measurements for nuclear events in four mediums. These results, scaled to 5 kt and normalized to tuff, are: tuff 1, granite 2.43, salt 2,63, and alluvium 0.18, for actual nuclear events; and ice 0.78, 100% saturated sand 0.56, 100% saturated till 0.67, and 57% saturated till 0.33, for simulated nuclear events in these mediums. The latter value for partially saturated till assumed a compressional velocity of 2400 m/sec for the medium. A lower assumed velocity reduces the values.