- © 1999 by the Seismological Society of America
The calculation of travel times and ray paths of seismic phases for a specified velocity model of the Earth has always been a fundamental need of seismologists. In recent years, the number of different phases used in analysis has been growing, as has the availability of new Earth models, especially models developed from detailed regional studies. These factors highlight the need for versatile utilities that allow the calculation of travel times and ray paths of (ideally) any conceivable seismic phase passing through (ideally) arbitrary velocity models. The method of Buland and Chapman (1983) provides significant progress toward this need by allowing for the computation of times and paths of any rays passing through arbitrary spherically symmetric velocity models. The implementation of this method through the ttimes software program (Kennett and Engdahl, 1991) for a limited number of velocity models and a standard set of seismic phases has been widely...