Three-dimensional P-wave velocity structure of the crust and upper mantle under the Changbai volcanic area in northeast China

We determined 3-D P-wave velocity structure of the crust and upper mantle under the Changbai volcanic area in northeast China by applying a tomographic method to a large number of arrival times from regional earthquakes and teleseismic events. A prominent low-velocity anomaly is clearly imaged in the crust and upper mantle down to 400- km depth beneath the Changbai volcano. A high-velocity anomaly is revealed in the mantle transition zone and deep earthquakes occurred actively there, suggesting that the stagnant Pacific slab exists in the mantle transition zone under the Changbai volcano. Our results suggest that the origin of the Changbai volcano is related to the deep dehydration of the subducted Pacific slab and corner flow in the big mantle wedge above the stagnant slab.