鲜水河、龙门山和安宁河三大断裂交汇地区震源应力场特征  

CHARACTERISTICS OF THE SEISMIC SOURCE STRESS FIELD IN THE INTERSECTION REGION OF XIANSHUIHE, LONGMENSHAN AND AN′NINGHE FAULTS

作　　者：龙思胜[1] 赵珠[1] 

机构地区：[1]四川省地震局,中国成都610041

出　　处：《地震学报》2000年第5期457-464,共8页Acta Seismologica Sinica

摘　　要：以鲜水河、龙门山和安宁河三大断裂交汇地区 ML=2 .2～ 3.7的 2 2次天然地震为资料 ,以 P波初动法求出震源机制解 ,并综合前人的研究结果 ,初步总结出该地区震源应力场和地震破裂的一些特征 .该区在自北西向南东方向近水平的区域应力场强烈挤压作用下 ,受复杂的地质结构影响 ,其震源应力场也表现出复杂多变的特点 .雅江、北三角和成都地块西部 3个分区 ,地震破裂以正断层、走滑型为主 ,表明垂向作用力在震源应力场中发挥了不可忽视的作用 ;宝兴天全地区的地震以逆断层、走滑型为主 ,其主压应力轴水平分量与浅层物质运移的南西方向一致 .笔者认为 ,多种形式的地震破裂组合 ,是大面积地壳浅层物质持续运移得以实现的微观机制 .WT5BZ]Twenty two earthquakes( M L= 2.2 ～ 3.7 ) in the intersection region of Xianshuihe, Longmenshan and An′ninghe faults are studied in this paper. The source mechanism solutions of these events are obtained by the P wave first motion method, and the characteristics of the source stress field and rupture in the intersection region are summarized preliminarily with some results of other researchers. Being strongly extruded by the approximately horizontal regional stress with the direction from north west to south east and the effect of the complex tectonics in the region, the source stress filed has complex and vamable characteristics. The earthquakes mainly show normal or strike slip faults in Yajiang, North triangle and west of Chengdu block areas, indicating that the vertical forces have been playing an important role in the source stress fields, while the earthquake mainly show reverse or strike slip faults in Baoxing Tianquan area, with the horizontal components of the principal pressure stress axis identical to the south west direction to which the shallow mass was moving. We think that the manifold combinations of earthquake faults are the micro mechanism based upon which the large regional shallow crust mass has been moving continually.

关 键 词：震源机制解 震源应力场 地震破裂 物质运移 

分 类 号：P315.33[天文地球—地震学] P315.727[天文地球—固体地球物理学]