Sterling revisited: The seismic source for a cavity‐decoupled explosion

In the STERLING event, a 0.38 kt nuclear device was exploded inside a roughly spherical cavity, of approximately 17 m radius. The cavity, located in the Tatum salt dome (near Hattiesburg, Mississippi), had been created by a 5.3 kt tamped explosion more than 2 years earlier (SALMON event). Analysis of data obtained in SALMON and STERLING indicated a corner frequency for STERLING near 10 Hz, a factor of 4 less than predicted by the simplest decoupling theory. We have performed a comprehensive re‐examination of the experimental records and find that the original report was incorrect, a consequence of not properly accounting for noise in the seismic analysis. The new study, based on direct spectral analysis of the free‐field data, indicates that the STERLING experiment was in near perfect agreement with theory. This is a potentially significant result for seismic monitoring of a low‐yield threshold test ban.