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Receiver Function Investigations of Seismic Anisotropy Layering Beneath Southern California
Author(s) -
Kong Fansheng,
Gao Stephen S.,
Liu Kelly H.,
Song Jianguo,
Ding Weiwei,
Fang Yinxia,
Ruan Aiguo,
Li Jiabiao
Publication year - 2018
Publication title -
journal of geophysical research: solid earth
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.983
H-Index - 232
eISSN - 2169-9356
pISSN - 2169-9313
DOI - 10.1029/2018jb015830
Subject(s) - anisotropy , geology , seismic anisotropy , shear wave splitting , layering , classification of discontinuities , mantle (geology) , isotropy , geophysics , crust , azimuth , receiver function , shear waves , shear (geology) , seismology , mineralogy , lithosphere , geometry , petrology , physics , tectonics , optics , mathematical analysis , botany , mathematics , biology
Seismic azimuthal anisotropy characterized by shear wave splitting analyses using teleseismic X K S phases (including S K S , S K K S , and P K S ) is widely employed to constrain the deformation field in the Earth's crust and mantle. Due to the near‐vertical incidence of the X K S arrivals, the resulting splitting parameters (fast polarization orientations and splitting times) have an excellent horizontal but poor vertical resolution, resulting in considerable ambiguities in the geodynamic interpretation of the measurements. Here we use P ‐to‐ S converted phases from the Moho and the 410‐ ( d 410) and 660‐km ( d 660) discontinuities to investigate anisotropy layering beneath Southern California. Similarities between the resulting splitting parameters from the X K S and P ‐to‐ S converted phases from the d 660 suggest that the lower mantle beneath the study area is azimuthally isotropic. Similarly, significant azimuthal anisotropy is not present in the mantle transition zone on the basis of the consistency between the splitting parameters obtained using P ‐to‐ S converted phases from the d 410 and d 660. Crustal anisotropy measurements exhibit a mean splitting time of 0.2 ± 0.1 s and mostly NW‐SE fast orientations, which are significantly different from the dominantly E‐W fast orientations revealed using X K S and P ‐to‐ S conversions from the d 410 and d 660. Anisotropy measurements using shear waves with different depths of origin suggest that the Earth's upper mantle is the major anisotropic layer beneath Southern California. Additionally, this study demonstrates the effectiveness of applying a set of azimuthal anisotropy analysis techniques to reduce ambiguities in the depth of the source of the observed anisotropy.