Asthenospheric Flow From East Asia to the Philippine Sea Plate Revealed by Rj‐MCMC Inversion of Surface Waves

Abstract

The Pacific and Philippine Sea Plate subductions have resulted in and controlled the development of a typical trench‐arc‐back‐arc system in NE Asia since the Cenozoic. The formation of widely distributed intraplate volcanoes and the dynamic pattern of the entire region are still debated. Here we constructed a three‐dimensional anisotropic S‐wave velocity model of NE Asia by inverting Rayleigh wave dispersion using a modified reversible‐jump Markov Chain Monte Carlo (rj‐MCMC) algorithm. The resulting model revealed a localized mantle upwelling beneath intraplate volcanoes in NE Asia and an ongoing lithospheric downwelling beneath the central Korean Peninsula. This suggests vigorous asthenosphere and lithosphere interactions, which is likely to control the spatial distribution of Cenozoic volcanoes. The fast directions show clockwise rotation beneath NE Asia, which eventually points to the Nankai Trough. This observation is broadly consistent with shear wave splitting and suggests the presence of mantle flow from East China to the Philippine Sea Plate. The slab window beneath the Nankai Trough within the Philippine Sea Plate subduction system may accommodate the mantle flow from East China. Our study indicates that the interaction of the Philippine, Pacific Sea Plates, and Eurasian Plates plays an essential role in controlling the mantle flow and intraplate volcanism of NE Asia.