East Asia Structure and Tectonics

Abstract

In this chapter, we review seismic tomography studies of the East Asia region and new insights into plate deep subductions, continental seismotectonics, intraplate magmatism, and mantle dynamics. The subducting Pacific slab is stagnant in the mantle transition zone under the Korean Peninsula and East China, and a big mantle wedge (BMW) has formed above the stagnant slab. Hot and wet upwelling flows in the BMW have caused intraplate volcanoes in NE Asia, lithospheric thinning and reactivation of the North China Craton, and large earthquakes in and around East China. Deep earthquakes in the Pacific slab may be related to a metastable olivine wedge in the slab. The deepest earthquakes (~ 600 km depth) under NE Asia may release more fluids preserved in the slab to the overlying BMW, contributing to the Changbai volcanism. The descending Indian plate beneath the Tibetan Plateau is clearly revealed. The Hainan volcano in South China is a hotspot fed by a deep mantle plume associated with plate deep subductions in the east and the west.