-------------------------------------------------------------------------------- Readme for the global SKS splitting compilation used in Becker, T. W., Lebedev, S., and Long, M. D.: On the relationship between azimuthal anisotropy from shear wave splitting and tomographic models. J. Geophys. Res., 117, B01306, doi:10.1029/2011JB008705, 2012. http://www-udc.ig.utexas.edu/external/becker/preprints/bll11.pdf -------------------------------------------------------------------------------- The SKS database consists of two files, a cleaned up, merged version of individual splits, and a station averaged file (see http://www-udc.ig.utexas.edu/external/becker/sksdata.html for references and updates). Thorsten Becker, August 2025 thwbecker@post.harvard.edu * Format description - Individual splits (14326 entries, including nulls) station lat lon azi d_azi dt d_dt type elat elon edep mlat mlon bazi > head ftp/becker2011.sks.table 007x 34.1000 241.4000 83.0 0.0 1.50 0.00 1 34.1000 241.4000 0.0 34.1000 241.4000 0.0 012x 34.1400 241.4400 81.0 0.0 1.35 0.00 1 34.1400 241.4400 0.0 34.1400 241.4400 0.0 028x 34.2800 241.4600 82.0 0.0 1.50 0.00 1 34.2800 241.4600 0.0 34.2800 241.4600 0.0 040x 34.3900 241.4700 273.0 0.0 2.35 0.00 1 34.3900 241.4700 0.0 34.3900 241.4700 0.0 043x 34.4200 241.4700 285.0 0.0 1.55 0.00 1 34.4200 241.4700 0.0 34.4200 241.4700 0.0 046x 34.4500 241.4700 79.0 0.0 1.30 0.00 1 34.4500 241.4700 0.0 34.4500 241.4700 0.0 061x 34.5800 241.5400 272.0 0.0 1.25 0.00 1 34.5800 241.5400 0.0 34.5800 241.5400 0.0 101 38.8340 77.5360 35.0 0.0 0.50 0.00 1 38.8340 77.5360 30.0 38.8340 77.5360 0.0 10 -23.6160 292.1550 91.0 0.0 0.80 0.00 1 -23.6160 292.1550 30.0 -23.6160 292.1550 0.0 10 -23.6160 292.1550 91.0 15.0 0.80 0.20 1 -23.6160 292.1550 0.0 -23.6160 292.1550 0.0 station: is the station name lat/lon: are the station coordinates, in degrees, latitude and longitude azi: the apparent fast polarization azimuth in degrees CW from North d_azi: the error in degrees (zero if not specified), dt: the delay time in seconds (zero if null), d_dt: the error in the delay time (0 if not given), If measurements are Nulls, both azi, dt, d_azi, and d_dt will be set to zero type: the type of measurement 1 = SKS 2 = local S 3 = Ppol 4 = SKKS 5 = PKS 6 = PKKS elon/elat: mlon/mlat: are event and path mid point coordinates. If not provided, or only partially provided, the station coordinates are used. edep: is the event depth, if provided, else set to zero. bazi: the back-azimuth (in degrees CW from N), if provided, else zero. - Averaged splits (5159 entries): arithmetically averaged for colocated sites. In this case, all event and mid point coordinates are set to the station coordinates, station names are set to "avg", and back-azimuth is set to zero. > head -4 ftp/becker2011.sks.avg.table avg -89.9800 0.0000 68.0 0.0 1.30 0.00 1 -89.9800 0.0000 0.0 -89.9800 0.0000 0.0 avg -75.0000 0.0700 73.0 0.0 0.50 0.00 1 -75.0000 0.0700 0.0 -75.0000 0.0700 0.0 avg 43.0600 0.1500 90.0 0.0 0.80 0.00 1 43.0600 0.1500 0.0 43.0600 0.1500 0.0 avg 40.8200 0.4900 82.9 32.6 0.99 0.19 1 40.8200 0.4900 0.0 40.8200 0.4900 0.0 As of 2025, the averaged format lists station names like so: > head -4 allwuest.tele.avg.table 002XXX_XN-avg1 34.060 241.420 76.0 0.0 1.50 0.00 1 34.0600 241.4200 0.0 34.0600 241.4200 0.0 005XXX_XN-avg1 34.080 241.400 346.0 0.0 1.20 0.00 1 34.0800 241.4000 0.0 34.0800 241.4000 0.0 007X-avg1 34.100 241.400 83.0 0.0 1.50 0.00 1 34.1000 241.4000 0.0 34.1000 241.4000 0.0 012X-avg2 34.140 241.440 81.0 0.0 1.38 0.04 1 34.1400 241.4400 0.0 34.1400 241.4400 0.0 where station names are listed with the number of averaged splits, based on grouping stations by location and listing the alphabetically first station name if there are multiples.