Panoptic View of Mantle Flow Beneath Trans‐Continental Northeast Asia: Distinct Variation Detected From ∼2,000 km Shear Wave Splitting Profile

Abstract

AbstractWe obtained a panoptic view of the pattern of mantle flow in the “Big Mantle Wedge” associated with the stagnation of the subducting Pacific slab. We applied a simultaneous inversion of multiple waveforms method to measure SKS‐wave splitting parameters for a dense seismic array in trans‐continental Northeast Asia. We identify distinct patterns separated by the North‐South Gravity Lineament (NSGL): to the west, the ENE fast axis orientation with small δt reflects limited frozen anisotropy in the stable lithosphere; while to the east, local variation of anisotropy is superimposed on the NNW‐dominated fast direction, suggesting contribution of other mechanisms rather than the only asthenospheric flow. Within a distance of 200 km crossing the NSGL, we reveal a gradual clockwise rotation in the fast direction, and the keel‐deflected flow caused by the 60–80 km reduction in the lithosphere thickness across the NSGL might contribute to the variation of anisotropy.