阶式断裂错动所引起的地表位移与应变观测效应  

Observational Effect Surface Displacement and Strain Produced by En Echelon Faulting

作　　者：张郢珍 粟生平[1] 

机构地区：[1]国家地震局分析预报中心

出　　处：《中国地震》1990年第1期65-70,共6页Earthquake Research in China

摘　　要：大的走滑断裂带,如鲜水河断裂,是由主干断裂及与其相伴的若干阶式(或平行)断裂组成。这种断裂的几何形状影响到断裂周围的应力、应变分布。本文利用三维位错理论分析了右旋左阶和右旋右阶断裂错动与单一断裂错动所产生的位移场及应变场的差别。计算结果表明,阶式断裂错动造成的地表效应与单一断裂的相应效应的图象有着不可忽视的区别。左阶断裂活动引起断裂重叠区的地表隆起及错动方向的线应变和体应变的压缩;而右阶断裂错动造成重叠区地表下沉和错动方向的线应变及体应变的膨胀。这两种阶式断裂的重叠区均是水平位移方向变化的转换区,而且这两种断裂周围的位移、应变图象要较单一断裂的图象不规则得多。Some large strike slip faults, such as the Xianshuihe fault, consist of main fault and several sub-faults, which are commonly arranged as en echelon (or parallel) pattern. The geometry of this kind of fault influences the distribution of stress and strain along the fault. We analyze the surface displacement and strain fields produced by left-step and right-step faulting for right lateral shear by using three-dimension dislocation model, and compare them with that produced by singly fault. The results indicate that the difference of the displacement and strain field pattern between en echelon fault and single fault can not be ignored for interpreting observational data. The left-step faultings tend to produce surface upwarps, compressive volumetric strain in and shorten linear strain in strike direction of the fault in the overlap of the echelon faults, while right-step faultings produce surface subside, dila-tional volumetric strain and lengthen linear strain. The overlop of the faults are the transform area of horizontal displacement in direction. The patterns of the displacement and strain field around the en echelon faults are more irregular than of single fault.

关 键 词：断裂 地表 位移 应变 错动 观测 

分 类 号：P315.7[天文地球—地震学]