NEOTECTONICS IN THE NORTHEASTERN SOUTH CHINA SEA AND ITS DYNAMIC MECHANISM

The northeastern South China Sea area is tectonically active because of its location in the convergent zone of Eurasian plate and Philippine Sea plate. According to seismicity, focal mechanism solution (FMS) and GPS data, we analyzed the characteristics of the neotectonics in this area, and put forward the dynamic mechanism of the neotectonics.On the basis of these data, it's suggested that the NW-trending subduction of Philippine Sea plate had stronger impact on the research area relative to the India-Tibet collision,and led to strong seismicity and NW-trending stress field. However, lateral stress transmission resulting from the collision also affected this area, and caused the South China Block to have moved southeastward. Meanwhile, the South China Block rotated counter-clockwise under the combined action of the two. The SE-trending lateral stress transmission counteracted the NW-trending compression produced by subduction and resulted in the westward-weakening seismicity and the clockwise-rotating axis P of FMS. Under this tectonical setting, the Binhai Fault Zone controls the earthquake and coastal tectonic uplift-subsidence of this area.