Mechanics of discontinuous faults
Mechanics of discontinuous faults
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DOI：
10.1029/jb085ib08p04337
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发表时间：
1980-08
影响因子：
--
通讯作者：
P. Segall;D. Pollard
中科院分区：
文献类型：
--
作者：
P. Segall;D. Pollard
故障迹线由许多离散的片段组成，通常排列成梯队阵列。在某些情况下，不连续面会影响沿断层的滑动和地震活动的分布。为了分析断层段，我们导出了均匀弹性材料中任意数目的不相交裂纹的二维解。该解包含了裂纹间的弹性相互作用。根据线性摩擦定律，假定裂纹表面粘着或滑动。对于梯队裂纹阵列，最大滑移与阵列长度的比值明显低估了驱动应力和摩擦阻力之间的差异。最大滑移与裂缝长度之比略高估了这一差异。右步和左步梯级不连续附近的应力分布在两个重要方面有所不同。对于右侧剪切和左步进裂纹，重叠裂纹两端的法向拉力增大并抑制摩擦滑动，而对于右侧步进裂纹，法向拉力减小并促进滑动。右步进裂缝之间的平均压应力也减小并促进了次级裂缝的形成，次级裂缝倾向于连接裂缝并允许滑移通过不连续面传递。左步进裂纹的平均应力增大；二次压裂更受限制，往往不会连接裂缝。地震群和余震聚集在沿着右侧断层的右侧台阶附近。我们的结果表明，左台阶储存弹性应变能，可能是大地震的地点。如果剪切感是左侧向的，则会产生相反的行为。
Fault traces consist of numerous discrete segments, commonly arranged as echelon arrays. In some cases, discontinuities influence the distribution of slip and seismicity along faults. To analyze fault segments, we derive a two-dimensional solution for any number of nonintersecting cracks arbitrarily located in a homogeneous elastic material. The solution includes the elastic interaction between cracks. Crack surfaces are assumed to stick or slip according to a linear friction law. For an array of echelon cracks the ratio of maximum slip to array length significantly underestimates the difference between the driving stress and frictional resistance. The ratio of maximum slip to crack length slightly overestimates this difference. Stress distributions near right- and left-stepping echelon discontinuities differ in two important ways. For right lateral shear and left-stepping cracks, normal tractions on the overlapped crack ends increase and inhibit frictional sliding, whereas for right-stepping cracks, normal tractions decrease and facilitate sliding. The mean compressive stress between right-stepping cracks also decreases and promotes the formation of secondary fractures, which tend to link the cracks and allow slip to be transferred through the discontinuity. For left-stepping cracks the mean stress increases; secondary fracturing is more restricted and tends not to link the cracks. Earthquake swarms and aftershocks cluster near right steps along right lateral faults. Our results suggest that left steps store elastic strain energy and may be sites of large earthquakes. Opposite behavior results if the sense of shear is left lateral.