Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models
Off-fault tensile cracks: A link between geological fault observations, lab experiments, and dynamic rupture models
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DOI：
10.1029/2011jb008577
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发表时间：
2012
影响因子：
--
通讯作者：
D. Ngo;Yonggang Huang;A. Rosakis;W. Griffith;D. Pollard
中科院分区：
文献类型：
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作者：
D. Ngo;Yonggang Huang;A. Rosakis;W. Griffith;D. Pollard
[1] 我们研究了具有弱速粘性区的半无限亚瑞利（慢于瑞利波速，cR）II 型裂纹尖端附近动态应力场的局部性质。我们使用动态光弹性实验的结果来约束模型，其中剪切破裂在 Homalite-100 板中沿着受远场单轴预应力作用的粘合、预切割和倾斜界面自发成核。在实验过程中，拉伸裂纹沿着剪切断裂界面的一侧以相对于剪切断裂界面大致恒定的角度周期性地生长。我们的分析模型解释了拉伸裂纹的发生和倾斜。经过轻微修改，该模型可以扩展到自然断层，为解释与挖掘断层上过去的地震相关的速度、方向性和静态预应力状态提供诊断标准。间接地，这种方法还允许人们限制自然破裂的速度减弱性质，提供现场地质学、实验室实验和地震学之间的重要联系。
[1] We examine the local nature of the dynamic stress field in the vicinity of the tip of a semi-infinite sub-Rayleigh (slower than the Rayleigh wave speed, cR) mode II crack with a velocity-weakening cohesive zone. We constrain the model using results from dynamic photoelastic experiments, in which shear ruptures were nucleated spontaneously in Homalite-100 plates along a bonded, precut, and inclined interface subject to a far-field uniaxial prestress. During the experiments, tensile cracks grew periodically along one side of the shear rupture interface at a roughly constant angle relative to the shear rupture interface. The occurrence and inclination of the tensile cracks are explained by our analytical model. With slight modifications, the model can be scaled to natural faults, providing diagnostic criteria for interpreting velocity, directivity, and static prestress state associated with past earthquakes on exhumed faults. Indirectly, this method also allows one to constrain the velocity-weakening nature of natural ruptures, providing an important link between field geology, laboratory experiments, and seismology.