Interpretation of Body and Rayleigh Waves from NTS to Tucson.

摘要

A linear array of eight Caltech portable broad-band seismograph trailers was set out from NTS to near Phoenix, Arizona, for the pre-announced underground nuclear test, OSCURO, on September 21, 1972. Travel-time and amplitude information were used to find an average crustal model by calculating synthetic seismograms using the Caniard-de Hoop method. Rayleigh waves from other nuclear events at NTS, as recorded at the Tucson WWSSN station, were examined as a control for determining the structure of the top half of the crust. Group-velocity curves were found and synthetic Rayleigh waves calculated for Tucson and Kingman (LRSM). The formations and characteristics of P sub n, a reflected P sub n, and the P sub g phases are examined. P sub g is demonstrated to be composed of the primary P reflection from the mantle and contains multiple arrivals of P-SV conversions. Comparisons of synthetic and observed seismograms indicate a crustal thickness of 30 km with a Poisson's ratio of 0.23. The crust-mantle transition appears to be sharp, jumping from 6.1 to 7.9 km/sec. The amplitude behavior of P sub n shows little evidence of any lid structure. (Author)