Analysis of present tectonic dynamic background in Northeast China based on focal mechanism

By collecting focal mechanism solutions of earthquakes at different depths from Northeast Japan to Northeast China during 1957 to 2022, the joint iterative stress inversion method is used to calculate the tectonic stress field in the subduction zone and the tectonic stress field state in Northeast China. The results show that the shallow area of the Japan trench is not only affected by the subduction and extrusion of the Pacific plate, but also related to the extrusion of the North American plate. The deep source earthquakes in Northeast China are closely related to the long-term action of the trench subduction zone. The formation of the Changbaishan volcanic area has a great relationship with the thrust of the subduction zone. The seismicity of the subduction zone indirectly controls the formation and activity of the volcanic area in Northeast Asia. The principal compressive stress axis distributes in the NEE-SWW direction in the Yingkou area of Liaoning, while the principal tensile stress axis distributes in the NNW-SSE direction. Based on the results of the focal mechanism of shallow earthquakes in the volcanic area and its surrounding areas, it is believed that the current tectonic stress field in the northeastern volcanic area continues the overall structure of stress in the northeastern region, with the principal compressive stress axis in the NEE-SWW direction and the principal tensile stress axis in the NNW-SSE direction.