Shallow slip amplification and enhanced tsunami hazard unravelled by dynamic simulations of mega-thrust earthquakes
Shallow slip amplification and enhanced tsunami hazard unravelled by dynamic simulations of mega-thrust earthquakes
复制标题
巨型逆冲地震的动态模拟揭示了浅层滑移放大和增强的海啸危险
作者：
S. Murphy;A. Scala;A. Herrero;S. Lorito;G. Festa;E. Trasatti;R. Tonini;F. Romano;I. Molinari;S. Nielsen
2011年日本东北大地震产生了意想不到的大量浅层滑动，极大地促进了随后的海啸。这类事件发生的频率如何？如何有效地模拟海啸灾害？随机滑动模型，可以快速计算，用于探索自然滑动的变化，但是，他们一般不专门处理浅滑功能。我们研究了系统的深度依赖性的滑动沿着逆冲断层与一些二维动态模拟使用随机剪应力分布和几何形状的基础上的横截面的东北断层。我们得到了一个概率密度的滑动分布，这与深度，地震的大小和破裂是否打破了表面。我们提出了一种方法来修改随机滑移分布根据这个动态导出的概率分布。这种方法可以有效地应用于产生大量的非均匀滑动分布的概率海啸危险性分析。使用大量的M9地震的情况下，我们证明，将动态派生的概率分布，并提高了条件概率的最大估计海啸波高沿着日本海岸。这种在随机模型中集成动力学特征的技术可以推广到任何俯冲带和断裂类型。
The 2011 Tohoku earthquake produced an unexpected large amount of shallow slip greatly contributing to the ensuing tsunami. How frequent are such events? How can they be efficiently modelled for tsunami hazard? Stochastic slip models, which can be computed rapidly, are used to explore the natural slip variability; however, they generally do not deal specifically with shallow slip features. We study the systematic depth-dependence of slip along a thrust fault with a number of 2D dynamic simulations using stochastic shear stress distributions and a geometry based on the cross section of the Tohoku fault. We obtain a probability density for the slip distribution, which varies both with depth, earthquake size and whether the rupture breaks the surface. We propose a method to modify stochastic slip distributions according to this dynamically-derived probability distribution. This method may be efficiently applied to produce large numbers of heterogeneous slip distributions for probabilistic tsunami hazard analysis. Using numerous M9 earthquake scenarios, we demonstrate that incorporating the dynamically-derived probability distribution does enhance the conditional probability of exceedance of maximum estimated tsunami wave heights along the Japanese coast. This technique for integrating dynamic features in stochastic models can be extended to any subduction zone and faulting style.