TauP SetSac

TauP SetSac uses the depth and distance information in SAC Tull [Tul89] file headers to put theoretical arrival times into the t0–t9 header variables. The header variable for a phase can be specified with by a dash followed by a number, for instance S-9 puts the S arrival time in t9. If no header is specified then the time will be inserted in the first header variable not allocated to another phase, starting with 0. If there are no header variables not already allocated to a phase, then the additional phases will not be added to the header. Note that this does not refer to times that are already in the SAC file before TauP SetSac is run. They will be overwritten. The ray parameter, in seconds per radian, is also inserted into the corresponding user0-user9 header.

Note that triplicated phases are a problem as there is only one spot to put a time. For example, in iasp91 S has three arrivals at 20~degrees but only one can be put into the choosen header. TauP SetSac assumes that the first arrival is the most important, and uses it. Additional header variables may be appended for the times of the multiples. For example, S-458 would put the first S arrival into header t4 and the second into t5 and the third into t8. If there are more arrivals than headers, the later arrivals are not added. If there are more headers than arrivals, then the header is not set.

Warning: TauP SetSac assumes the evdp header has depth in meters unless the --evdpkm flag is used, in which case kilometers are assumed. This may be a problem for users that improperly use kilometers for the depth units. Due to much abuse of the SAC depth header units, a warning message is printed if the depth appears to be in kilometers, i.e. it is < 1000, and --evdpkm is not used. This can be safely ignored if the event really is less than 1000 meters deep. See the SAC manual Tull [Tul89] for confirmation.

The SAC files must have evdp and the o marker set. Also, if gcarc or dist is not set then TauP SetSac can calculate a distance only if stla, stlo, evla and evlo are set.

The user should be very careful about previously set header variables. TauP SetSac will overwrite any previously set t or user headers. A future feature may do more careful checking, but the current version makes no effort to verify that the header is undefined before writing.

If the given filename is a directory, TauP SetSac will recursively look for files within that directory to process. Thus, a large directory structure of Sac files can be processed easily.

For example, if the event and station headers are set in my_earthquake.sac, then this will set travel times for P and S into the T0 and T1 headers:

taup setsac -p P,S my_earthquake.sac

The usage is:

Usage: taup setsac [--debug] [--evdpkm] [--geodetic] [--help] [--verbose]
                   [--geodeticflattening=f] [--prop=<toolPropsFilename>]
                   [[--mod=<modelName>] [-h=depth[,depth...]]...
                   [--stadepth=depth[,depth...]]... [--scat=s s]...] [[-p=phase
                   [,phase...]]... [--phasefile=<phaseFiles>]...] [sacfile...]
Set headers to travel times of phases using depth and distance from SAC files.
      [sacfile...]   SAC files to process

Options:

      --debug        enable debugging output
      --evdpkm       sac depth header is in km, default is meters
      --geodetic     use geodetic latitude for distance calculations, which
                       implies an ellipticity. Default is spherical. Note this
                       only affects calculation of distance from lat/lon pairs,
                       all travel time calculations are done in a purely
                       spherical model.
      --geodeticflattening=f
                     Inverse Elliptical flattening for distance calculations
                       when --geodetic, defaults to WGS84 ~ 298.257. The
                       distance calculation uses 1/x.
      --help         display this help message
      --prop=<toolPropsFilename>
                     load defaults from properties file
      --verbose      enable verbose output
Model Args
  -h, --evdepth, --sourcedepth=depth[,depth...]
                     source depth in km
      --mod, --model=<modelName>
                     use velocity model "modelName" for calculations.
                     Default is iasp91. Other builtin models include prem,
                       ak135, ak135fcont, and ak135favg.
      --scat, --scatter=s s
                     scattering depth and distance in degrees, which may be
                       negative. Only effects phases with 'o' or 'O' in the
                       phase name.
      --stadepth, --receiverdepth=depth[,depth...]
                     the receiver depth in km for stations not at the surface
Phase Names
  -p, --ph, --phase=phase[,phase...]
                     seismic phase names
      --phasefile=<phaseFiles>
                     read list of phase names from file