Department of Earth Sciences
University of Southern California
Los Angeles

SKS splitting compilation

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This work was made possible by the willingness of seismologists to share their results, and our database is largely based on, and reusing, the compilation efforts of G. Barruol, A. Wüstefeld, M. Fouch, D. Schutt, and P. Silver. In particular, our database is not meant to reproduce the ongoing efforts by G. Barruol to keep Wüstefeld's et al.'s (2009) SKS database updated.

However, our compilation does hold back-azimuth and event data for some of the studies, information not available for some of the other compilations. References for the source data bases we use include:

  • Wüstefeld, A. and Bokelmann, G. H. R. and Barruol, G. and Montagner, J. P.: Identifying global seismic anisotropy patterns by correlating shear-wave splitting and surface-wave data, Phys. Earth Planet. Int., 176, 198-212, 2009. Database available online at (Version as of 05/2011 was used for Becker et al., 2012; for the current version, see below).
  • Fouch, M.: Upper Mantle Anisotropy Database, Online at, accessed 06/2006, 2006.
  • Silver, P. G.: Seismic anisotropy beneath the continents: probing the depths of geology, Ann. Rev. Earth Planet. Sci., 24, 385-432, 1996.
In addition to merging existing compilations and adding back-azimuth information to many of the studies, we are adding a small number of individual studies not found (fully, at the time of merging) in the other compilations, as listed below.
Current SKS data files
We continue to update our SKS splitting database. The newest version (as of October 23, 2014) can be found below, the format is as described in the README for the old version of the database above: We also have generalized spherical harmonics expansions of those data, please contact me if interested.

Besides the studies used for Becker et al. (2012), we current include the additional work by

  • An updated (01/2013) version of Wuestefeld et al.'s (2009) splitting database.
  • Miller, M. S., Allam, A. A., Becker, T. W. and Di Leo, J., and Wookey, J.: Constraints on the geodynamic evolution of the westernmost Mediterranean and northwest Africa from shear wave splitting analysis. Earth Planet. Sci. Lett., 375, 234-243 2013. (PDF)
  • Refayee, H. A., B. B. Yang, K. H. Liu, and S. S. Gao (2013): Mantle flow and lithosphere-asthenosphere coupling beneath the southwestern edge of the North American Craton: Constraints from shear-wave splitting measurements, Earth Planet. Sci. Lett.,
  • Leon Soto, G., E. Sandvol, J. F. Ni, L. M. Flesch, T. M. Hearn, F. Tilmann, Y. J. Chen, and L. Brown (2012): Significant and Vertically Coherent Seismic Anisotropy Beneath Eastern Tibet. J. Geophys. Res., doi:10.1029/2011JB008919.
You might want to use Barruol and Wüstefeld's SKS database instead, which has more complete references to original studies, and a very nice map and search interface.
Database as of Becker et al. (2012)
For reproducibility, we here provide the SKS splitting database that was used for our study on global mantle azimuthal anisotropy:
  • 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. (PDF)
Our study included the Wuestefeld et al. (2009) in the 05/2011 version, with partially augmented information such as back-azimuths, along with several additional studies, including:
  • Fouch, M.J., and J.D. West (2011): The mantle flow field beneath the western United States, in prep.
  • Civello S., Margheriti L. (2004): Toroidal mantle flow around the Calabrian slab (Italy) from SKS splitting, Geophys. Res. Lett., 31, doi:10.1029/2004GL019607.
After removal of textual exact duplicates, the individual split compilation as of Becker et al. (2012) contained 14,326 entries including nulls. This compilation does hold, however, actual duplicate data entries with different notation (e.g. slight differences in station location accuracy) which are removed in a next step. Moreover, not all original papers provided event information (needed for back-azimuthally-dependent averaging) and only some of the entries in the databases distinguished between individual splits and station-averages. We therefore proceeded to process the original SKS splits by performing a simple, arithmetic average for all (approximately) co-located entries. This yielded 5,159 averaged entries; both data bases are provided for download below:

[news] [research] [teaching] [group] [publications] [CV] [contact]
downloads: [software] [tomography] [visualizations] [global maps] [SKS] [papers]
Updated: October 23, 2014. (c) USC Geodynamics