Crust and upper mantle anisotropy beneath the Japan Sea and NE China from inversion of surface wave dispersion using rj-MCMC method

Abstract:

Surface wave dispersion data with azimuthal anisotropy can be used to invert for wavespeed azimuthal anisotropy, which provides essential dynamic information about depth-varying deformation of the Earth’s interior. The traditional method to slove this inversion problem is a two-step scheme, i.e. inverting the isotropic wavespeed first, based on which the anisotropic part is solved successively. In this study, we simultaneously invert both isotropic and anisotropic shear wave velocity using the rj-MCMC (reversible jump Markov Chain Monte Carlo) algorithm, which allows sampling the model space in a transdimensional way.

We apply the method to obtain crustal and upper mantle azimuthal ansiotropy of Northeast Aisa, including the Eastern North Chian Craton (ENCC) and Northeast China (NE China), Korean Peninsula and the sea of Japan (see Fig. 1), using Rayleigh wave dispersion data from a recent two-station surface wave tomographic study by Fan et al. (2020). The 3-D isotropic and anisotropic shear wave velocity model beneath Northeast Aisa we obtained, together with previous SKS studies, reveal the possible origion of some intraplate volcanos and exhibit a large-scale dynamic characteristic of this area.