This is a collection of routines for computing surface displacements, strain, and tilts from a rectangulat dislocation in an elastic halfspace. The basic computation is done by the standard Okada routines; however this package provides the ‘‘wrapping’’ to make these easier to use in geographical coordinates. There are separate routines for finding the response at a single location, or over a grid; and also a routine for finding the relative sensitivity of different elements of a fault plane to particular measurements (needed for inversion).
A gzipped tar file of the routines and documentation is available here.
NOTE--before a bug fix on 9 Oct 2006, this program gave repeat times that are too short by 1 sec exactly.
This program, given a set of concatenated .sp3 files, and a time and place (on the command line), writes out the repeat time for each GPS satellite: that is, the time until the satellite is at the same place in the sky (elevation and azimuth): that is, the same aspect. This information is useful in correcting high-rate GPS data; see, for example, Choi et al, Geophysical Research Letters, 2004, paper L22608 (available here as paper 41). Here is a preprint describing some results using artrep. The program gives the difference in place (in milliradians on the sky), as well as the elevation, azimuth, and some additional information. The computation is done using polynomial interpolation from the 15-minute ECEF positions in the .sp3 file; see this site for code and discussion.
The program (Fortran 77) is available here. For a routine that uses the broadcast ephemeris, and is not station-specific, see Kristine Larson's program.
Thanks to Kristine Larson for comments and testing.
See here for more information, including the code; the program is described in this paper.