SEISMIC EFFICIENCY OF DECOUPLED NUCLEAR-EXPLOSIONS

Experimental observations of the seismic efficiency of a decoupled nuc lear explosion in a salt dome are presented. The energy decoupling fac tor was calculated from local, regional and teleseismic data using the ratio of the amplitudes of the tamped (well coupled) explosion that h ad created the cavity and that of the decoupled one. To calculate the amplitudes of the seismic waves of a well coupled explosion of the sam e yield as the decoupled one, a scaling law for explosions fired withi n the same region was used. An energy decoupling factor near 30 is con sistent with local, regional and teleseismic data. It is concluded tha t decoupling was only partial for the event described. Numerical calcu lations of partial decoupling showed that the seismic wave spectrum at an epicentral distance of 2.3 km is consistent with an amplitude deco upling factor of 20, which is consistent with the energy decoupling fa ctor 30.