The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis
The Influence of Depth‐Varying Elastic Properties of the Upper Plate on Megathrust Earthquake Rupture Dynamics and Tsunamigenesis
复制标题
上部板块随深度变化的弹性特性对巨型逆冲地震破裂动力学和海啸发生的影响
DOI：
10.1029/2021jb022328
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
D. Peter
中科院分区：
文献类型：
--
作者：
M. Prada;P. Galvez;J. Ampuero;V. Sallarés;C. Sánchez;J. Macías;D. Peter
逆冲断层周围岩石的弹性特性强烈地影响着大地震。与摩擦相反，这些性质可以从沿着孕震带的地球物理测量中就地导出。然而，它们往往被高估的数值模拟，特别是在浅巨型逆冲断层。在这里，我们探讨的影响，现实的深度变化的上板弹性特性沿着的巨型逆冲断层地震破裂动力学和海啸成因的三维动态破裂和海啸模拟。我们比较结果从三个俯冲带的情况下，均匀和非均匀的弹性介质，和双材料故障。非均质模型中的弹性性质遵循来自俯冲带受控源层析成像模型的真实深度分布。我们假设所有情况下的摩擦特性相同。非均质和均质模型中的模拟表明，刚度深度变化解释了滑动、滑动速率、频率含量和破裂时间的深度变化行为。深度变化的滑动行为，频率内容，和破裂持续时间定量同意以前的预测基于全球数据汇编，解释了海啸地震和大型浅层巨型逆冲断层地震的主要深度相关特征。双材料模拟中的大滑移、缓慢破裂和滑移率放大在很大程度上受断层最柔顺侧的弹性岩石性质控制，在俯冲带中，断层最柔顺侧是上板块。非均匀模型的大的浅滑动和向沟增加的上板柔度导致最大的同震海底变形和海啸振幅。这突出了考虑实际上的上板块刚度变化的重要性，以正确评估巨型逆冲断层地震的海啸发生潜力。
Megathrust earthquakes are strongly influenced by the elastic properties of rocks surrounding the fault. In contrast to friction, these properties can be derived in situ from geophysical measurements along the seismogenic zone. However, they are often overestimated in numerical simulations, particularly in the shallow megathrust. Here we explore the influence that realistic depth‐varying upper‐plate elastic properties along the megathrust have on earthquake rupture dynamics and tsunamigenesis using 3D dynamic rupture and tsunami simulations. We compare results from three subduction zone scenarios with homogeneous and heterogeneous elastic media, and bimaterial fault. Elastic properties in the heterogeneous model follow a realistic depth‐distribution derived from controlled‐source tomography models of subduction zones. We assume the same friction properties for all scenarios. Simulations in the heterogeneous and homogeneous models show that rigidity depth variations explain the depth‐varying behavior of slip, slip rate, frequency content, and rupture time. The depth‐varying behavior of slip, frequency content, and rupture duration quantitatively agree with previous predictions based on worldwide data compilations, explaining the main depth‐dependent traits of tsunami earthquakes and large shallow megathrust earthquakes. Large slip, slow rupture and slip rate amplification in bimaterial simulations are largely controlled by elastic rock properties of the most compliant side of the fault, which in subduction zones is the upper plate. Large shallow slip and trenchward increasing upper‐plate compliance of the heterogeneous model lead to the largest co‐seismic seafloor deformation and tsunami amplitude. This highlights the importance of considering realistic upper‐plate rigidity variations to properly assess the tsunamigenic potential of megathrust earthquakes.
影响因子：
3.5
作者：
Harders, Rieka;Ranero, Cesar R.;Behrmann, Jan H.
通讯作者：
Behrmann, Jan H.