PROJECT GNOME VOLUNTEER SEISMOLOGICAL TEAMS

Abstract

Forty‐three volunteer seismological teams participated in monitoring the three‐kiloton nuclear detonation of December 10, 1961. Nearly all the teams were within a radius of 600 miles of GNOME ground zero, located approximately 25 miles southeast of Carlsbad, New Mexico, and most were in or near the Delaware Basin. Standardized methods of calibrating the seismic equipment and synchronizing time references were required to obtain accurate data on the amplitudes and travel times of seismic waves. Calibration of seismograph systems was done by a weight‐drop method. A voice count before and after the shot, as well as audible pulses each second, were transmitted over a special broadcast network to synchronize the timing. Gain settings were based on data from a previous nuclear detonation of comparable size. Seismic wave travel times for the Central United States were used to estimate times of first arrival at each team. As evidenced by the quality of records and considering the limited data available upon which to base operational procedures, the volunteer‐team monitoring of the GNOME event was a successful effort.