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Crustal Radial Anisotropy of the Iran Plateau Inferred From Ambient Noise Tomography
Author(s) -
Movaghari R.,
JavanDoloei G.,
Yang Y.,
Tatar M.,
Sadidkhouy A.
Publication year - 2021
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 - 10.1029/2020jb020236
Subject(s) - geology , anisotropy , crust , seismic anisotropy , seismology , tomography , seismic tomography , shear velocity , mantle (geology) , rayleigh wave , geophysics , shear (geology) , surface wave , petrology , physics , turbulence , mechanics , optics
This study presents a three‐dimensional (3D) model of the crustal and uppermost mantle shear wave velocity and radial anisotropy beneath the Iran Plateau constructed by Rayleigh and Love waves from ambient noise. We correlate three years of continuous seismic ambient noise data recorded in 98 stations to obtain cross correlation functions. Then, we measure Rayleigh (8–60 s) and Love (8–50 s) wave dispersion curves from these cross‐correlation functions to generate two‐dimensional dispersion maps using a fast marching surface tomography method. Finally, we build a quasi‐3D shear wave velocity and radial anisotropy model by jointly inverting Rayleigh and Love local phase velocity dispersion curves using a Bayesian Markov chain Monte Carlo inversion method. Observed radial anisotropy beneath Central Iran is weaker than adjacent areas. Negative radial anisotropy is observed in the shallow structures across our study region, which is most likely attributed to vertically aligned cracks in the upper crust. Strong positive radial anisotropy in the middle to the lower crust beneath the Zagros is imaged, which is associated with ductile shear zones in the crust. Radial anisotropy changes from positive values in the crust to negative values in the upper mantle beneath the Zagros, which may be evidence for the decoupling of the crust from the upper mantle beneath the Zagros.