Scattering of teleseismic body waves under Pasadena, California


Teleseismic receiver functions for structure under Pasadena, California (PAS) are derived from azimuthally distributed teleseismic P waves recorded on Benioff 1-90 instrumentation. The broadband three-component Benioff 1-90 system is peaked at a 1-s period and allows resolution of major crustal interfaces from large Ps conversions seen in the receiver function data. The observed body wave data are quite complex, showing exceptionally large Ps conversions and scattered waves on horizontal components. Radial and tangential motions are of equal magnitude and show major off-azimuth converted Ps waves, suggesting large-scale crustal heterogeneity beneath the station. Analysis of a major Ps conversion arriving 3 s after direct P indicates that a major crustal discontinuity at about 20 km depth dips at moderate angles to the north under the San Gabriel Mountains. This interface probably represents the crustal tectonic boundary between the Transverse Ranges and the Los Angeles Basin. -from Author

Publication Title

Journal of Geophysical Research