Calibration of the Yellowknife Seismic Array with First Zone Explosions

Abstract

Recordings from a crustal seismic experiment, which was conducted in the Yellowknife area in 1966, were used for calibration of the Yellowknife seismic array. In the immediate vicinity of the array the crust is found to be very uniform. A superficial layer with an intercept time of 0.172±0.012 s and unknown velocity is underlain by a crust with a P wave velocity of 6.04 ± 0.01 km s−1 near the top: assuming this velocity constant throughout the second layer, the total thickness of the crust is about 34±2 km. The Mohorovicic discontinuity is horizontal under the array within the resolution of this experiment and the apparent Pn velocity is 8.15 km s−1. At a distance of a few tens of kilometres the crustal uniformity breaks down. The distances are such that, for most teleseismic signals, the effect of these in homogeneities should be negligible.