PcP from the nuclear explosion BILBY September 13, 1963

Abstract

The core-reflected phase, PcP, from the BILBY event, received at stations between 19° and 88°, arrived early by an average of 1.80 seconds with respect to the Jeffries-Bullen tables. The standard deviation of these data was 0.77 seconds. The corresponding P phases were early by 1.34 seconds. The tables therefore need adjustments. If the core boundary is to be moved by more than 10 km from the value of 2898 km then the mantle seismic velocity immediately above the core must be changed also. The PcP/P amplitude ratios are nearly always much larger than those predicted theoretically.