The travel times of S and SKS

Abstract

abstract Observations are reported of the travel times of S and SKS for arc distances of 30° to 126°. It was found that for S the new times do not differ significantly from the Jeffreys-Bullen tables up to 80° and are up to 4 seconds later between 80° and 100°. The apparent velocity found for the diffracted S phase was 1/8.941 degrees per second agreeing well with that reported by Cleary. The S station anomalies found in this study were about four times those for P in agreement with the earlier analysis of Doyle and Hales. As was the case for P the travel times for S can be fitted to within experimental error by a quadratic in Δ. However, in this case, the values of dT/d Δ found from the raw data suggest that there is a discontinuity in dt/d Δ at about 42°.