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本文使用地震资料研究了青藏高原与华南块体边界南北地震带南段的地震类型及其构造运动的区域特征.发现金沙江上游东侧与鲜水河南侧之间的正断层型地震活动区,存在南北向扩张的地震构造运动;金沙江下游东侧正断层型地震活动区存在东西向扩张的地震构造运动.在龙门山断裂及其西北相邻地震带是一个逆断层型地震活动区.其他地区多为走滑型地震.南北地震带南段东西两区域地震应力场主压应力P轴方向呈现区域性差异.南北地震带南段西部区域的应力场主压应力P轴的方向大部都沿北东-南西方向分布,这与青藏高原地区的主压应力P轴的方向分布一致.南北地震带南段东部区域的主压应力P轴的方向大部都沿北西-南东方向分布,与华南地区的应力场大致相同.南北地震带南段东、西两区主压应力P轴方向所呈现出的不连续性分布特征,表明了南北地震带南段东部区域的地震孕力场可能是另有一个北西-南东方向分布的孕震力源的应力场.它可能与台湾纵谷断层地区菲律宾海板块北西向挤压的构造应力场有关.
In this paper, we use seismic data to study the types of the earthquakes and their tectonic movements in the southern segment of the South-North Seismic Belt along the boundary between the Qinghai-Tibet Plateau and the South China block.We find that the normal faulting area between the east of Jinsha River upstream and the south of Xianshui River, There is an extensional north-south seismic tectonic movement; there is an east-west expanding seismic movement in the normal fault-type seismic activity zone on the east side of the downstream Jinsha River, and an inverse-faulting seismic zone in the Longmen Shan fault and its adjacent northwestern seismic zone. Most of them are strike-slip type earthquakes.The P-axis direction of the principal stress of seismic stress field in the eastern and western regions of the south segment of the north-south seismic zone shows a regional difference.The stress field in the western part of the southern segment of the South- Which is consistent with the direction of the P-axis of the principal compressive stress in the Qinghai-Xizang Plateau.The P-axis direction of the major compressive stress in the eastern part of the southern segment of the South-North Seismic Belt mostly distributes from northwest to south-east, Which is similar to the stress field in South China.The distribution of discontinuities in the P axis of the main compressive stress in the east and west of the southern segment of the South-North Seismic Belt shows that the south-north seismic zone The earthquake stress field in the east segment of the segment may be another stress field in the NW-SE distribution that may be related to the tectonic stress field of the Philippine Sea Plate in the westward crust of the Taiwan Rift Fault Zone.