Rupture termination at restraining bends: The last great earthquake on the Altyn Tagh Fault
Rupture termination at restraining bends: The last great earthquake on the Altyn Tagh Fault
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DOI：
10.1002/2015gl063107
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发表时间：
2015-04
影响因子：
5.2
通讯作者：
A. Elliott;M. Oskin;J. Liu-zeng;Y. Shao
中科院分区：
文献类型：
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作者：
A. Elliott;M. Oskin;J. Liu-zeng;Y. Shao
断层走向的变化增加库仑破坏应力时，走滑破裂传播不稳定。这种现象的数值模型提供了预测破裂程度的基础上弯曲几何形状，但尚未得到验证的现场数据。为了测试模型预测的破裂障碍，我们检查破裂程度沿着一段的左阿尔金断裂打断了三个主要的双弯。我们测量了3-8米的偏移量，并绘制了>95公里的连续陡崖，这些陡崖定义了最近的地表破裂。我们记录了这个破裂的东部终点在阿克赛弯曲，在那里一个未变形的更新世冲积扇，我们映射和日期重叠的故障。我们的结论是，根据这一地貌证据，多个全新世断裂已停止在阿克赛弯曲。我们的现场数据验证了在>18°约束弯曲处破裂终止的模型预测，并支持使用几何参数来定义地震危险性模型中预期的地震大小。
Strike‐slip rupture propagation falters where changes in fault strike increase Coulomb failure stress. Numerical models of this phenomenon offer predictions of rupture extent based on bend geometry, but have not been verified with field data. To test model predictions of rupture barriers, we examine rupture extent along a section of the sinistral Altyn Tagh Fault punctuated by three major double bends. We measure 3–8 m offsets and map >95 km of continuous scarps that define the most recent surface rupture. We document the eastern terminus of this rupture within the Aksay bend, where an undeformed Pleistocene alluvial fan we mapped and dated overlaps the fault. We conclude, based on this geomorphologic evidence, that multiple Holocene ruptures have stopped in the Aksay bend. Our field data validate model predictions of rupture termination at a >18° restraining bend and support use of geometric parameters to define expected earthquake sizes in seismic hazard models.