Seismic determination of impact times of supersonic projectiles

A seismic system for detection and determination of impact times for supersonic projectiles was developed and tested. The study included: (1) a pretest seismic refraction survey to characterize subsurface conditions within the target area as well as (2) design and testing of the seismic detection array under test conditions. The refraction test indicated that operation of a geophone at minimum gain of 60 dB should allow good records of impacts at distances of 300 meters, at least. A further comparison test was derived by firing explosive charges near some impact craters and recording these with the array. The times were well within 10 millisecond accuracy. This technique was recommended for all future tests as the means of determining impact time.