SeismicHandler - Waveform Analysis Tool

The travel time tables of SH/SHM

For several options SH/SHM use its own travel time tables. All the file must reside in $SH_INPUTS and have an extension .TTT. For historic reasons (the VAX/VMS origin of the program) the travel time table filenames use all uppercase letters. To translate a phasename with lowercase letters in it to the corresponding filename convert the lowercase letter to uppercase and precede it by an uppercase V. E.g. the phase pPcP translates into the filename VPPVCP.TTT. The format of the files is described below. The travel time tables supplied in the distribution are based on the IASP91 velocity model (for teleseismic phases). They were created using the program ttimes of Ray Buland. You may replace the existing files by your own version (but keep a copy of your files on a private directory, so you can restore them after making a complete update of SH/SHM) or add travel times tables of new phases to the directory. SHM makes no restrictions on using arbitrary phasenames, except phases starting with lowercase b and phases with V or v in the name (see above).

The format of the files

When a travel time is computed, SHM reads the table of the phase and interpolates linearly in both variables, distance and depth.

This page last modified 10-Sep-2005