Infrasonic observations of the Direct Course high explosive test

Abstract

Direct Course was an experiment involving the detonation of 600 tons of high explosive at the White Sands Missile Range, New Mexico, on 26 October 1983. Direct Course afforded an opportunity for long‐range measurements of infrasound propagation. Measurements were made at four stations along a northward bearing from the source at ranges from 250 to 865 km. Each station consisted of an array of sensors covering the frequency range from about 0.1 to 10 Hz. Analysis of signals across an array provide azimuth, horizontal trace velocity, and power spectra of the signal. At the closer stations the signals contain a “precursor” which arrived well before the direct‐acoustic‐travel arrival time. The principal signal following the precursor region was approximately 13 min in length. Power spectra show the signal to be concentrated in the 0.15‐to 1.5‐Hz region. Observations of attenuation of the signal and of changes in detailed spectral characteristics are possible with the multi‐station observations. Tentative inte...