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A Method for Estimating the Crustal Azimuthal Anisotropy and Moho Orientation Simultaneously Using Receiver Functions
Author(s) -
Wang Pan,
Huang Zhouchuan,
Wang Xingchen
Publication year - 2020
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 - 10.1029/2019jb018405
Subject(s) - azimuth , anisotropy , geology , orientation (vector space) , polarization (electrochemistry) , birefringence , seismology , transverse plane , hyperparameter optimization , geodesy , geometry , physics , optics , computer science , mathematics , chemistry , structural engineering , engineering , artificial intelligence , support vector machine
The P ‐to‐ S converted phase at the Moho (the Pms phase) contains important information regarding the crustal structure. Here, we employ a grid search approach to simultaneously extract the bulk crustal azimuthal anisotropy and Moho orientation using receiver functions. The solution of this approach is the weighted average of two individual subfunctions that separately analyze the birefringence and arrival time of the Pms phase. Since a tilted Moho deflects the polarized components of the Pms phase, the Pms birefringence subfunction minimizes the energy on all the transverse polarization components (i.e., the transverse polarization direction before Pms splitting). The implementation of this subfunction is similar to that of the transverse component minimization method, but the Moho orientation is considered. The Pms arrival time subfunction takes into account both the crustal anisotropy and the Moho orientation to predict and fit Pms arrivals. According to extensive synthetic experiments, this approach is remarkably robust to the presence of strong anisotropy, a steep Moho, and slightly tilted fast axes (less than 30°). This approach is also highly tolerant of random noise and data with uneven azimuthal coverage. We apply this approach to three permanent stations on the Tibetan Plateau. The resulting measurements boast a high quality and are consistent with the crustal anisotropy and Moho orientation revealed in previous studies.