The S receiver functions: synthetics and data example

SUMMARY Recently, the S receiver function method has been successfully developed to identify upper mantle interfaces. S receiver functions have the advantage of being free of S ‐wave multiple reflections and can be more suitable than P receiver functions for studying mantle lithosphere. However, because of specific ray geometry and interference of diverse phases, the S receiver function method has some technical difficulties and limitations. We use synthetic seismograms to demonstrate the feasibility and limitations of S receiver functions for studying mantle structures. Full‐wavefield seismograms were calculated using the reflectivity method and processed to generate synthetic S receiver functions for S , SKS and ScS waves. Results show that S receiver functions can be obtained from waveforms of S , SKS and ScS waves. The synthetic S receiver functions for these incident waves show S ‐to‐ P converted phases at all discontinuities in the crust and upper mantle. Useful ranges of epicentral distances for calculation of S receiver functions are: 55°–85° for S , >85° for SKS and 50°–75° for ScS waves. We apply both the S and P receiver function methods to data recorded at broadband station YKW3 in Northwest Canada. The study shows that there is significant agreement among different receiver function methods, and demonstrates the usefulness of S receiver functions for imaging the mantle lithosphere.