Crustal velocity structure and collision boundary between the Sino-Korea and Yangtze blocks in the Yellow Sea

Abstract

P wave velocity structure in the crust of the Yellow Sea region was inverted by using P wave arrival data from the earthquakes recorded by Chinese, Korea and ISC stations. Taken together with gravity anomaly and fault system, Pn velocity and anisotropy, we analyzed the relation of various geophysical anomalies and the tectonic difference in the western and eastern Yellow Sea. This work provided further information for locating the eastern Yellow Sea fault zone and the collision boundary between the Sino-Korea and Yangtze blocks. The crust of the northern Yellow Sea and western South Yellow Sea shows a character of sedimentary basin, and their low P-wave velocities suggest thick deposits and large-scale depressions, particularly in the northern Yellow Sea, Haizhou Bay and southern South Yellow Sea basin. In contrast, the high velocity in the crust of the central South Yellow Sea, Jiaodong peninsula, Liaodong peninsula and Korea peninsula show a character of tectonically uplifted areas. The NE-oriented high-velocity anomalies in the central South Yellow Sea are correspondent to tectonic strikes in the Jiaodong peninsula, but they are not connected with those in Korea peninsula, obviously separated by a gap. We infer that there may be a NS-oriented deep fault zone (the eastern Yellow Sea fault zone) between the southern Yellow Sea and Korea peninsula, but still need more data from the eastern Yellow Sea and Korea peninsula to confirm its relation with the collision boundary between the Sino-Korea and Yangtze block.