基于震源机制分析中国东北地区现今构造动力学背景

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

通过收集1957—2022年以来日本东北至中国东北地区的不同深度的地震震源机制解,采用联合迭代应力反演的方法,计算俯冲带构造应力场及中国东北地区构造应力场状态。研究结果显示:日本海沟浅部区域不仅受到太平洋板块的俯冲挤压,也与北美板块的推挤作用有关;中国东北区域的深源地震与海沟俯冲带的长期作用存在密切的联系。长白山火山区的形成与俯冲带的逆冲存在巨大的联系,俯冲带的地震活动间接控制着东北亚火山区的形成与活动。辽宁营口地区主压应力轴分布于NEE-SWW方向,主张应力轴分布于NNW-SSE方向。结合火山区及周边浅源地震震源机制的结果,认为东北火山区现今构造应力场延续了东北区域应力的整体结构,主压应力轴呈NEE-SWW向,主张应力轴呈NNWSSE向。

By collecting focal mechanism solutions of earthquakes at different depths from Northeast Japan 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.