Stochastic model of heterogeneity in earthquake slip spatial distributions
Stochastic model of heterogeneity in earthquake slip spatial distributions
复制标题
地震滑动空间分布非均质性的随机模型
DOI：
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发表时间：
2006
期刊：
影响因子：
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通讯作者：
R. Archuleta
中科院分区：
文献类型：
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作者：
D. Lavallée;Pengcheng Liu;R. Archuleta
总结
断层-震源反演揭示了地震滑动或断层面预应力分布的空间复杂性。本研究的基本假设是，一个随机模型可以再现振幅的变化和空间滑动分布的长期相关性。本文计算了1979年帝王谷、1989年洛马普列塔、1994年北岭和1995年兵库县南部（科比）四个地震震源模型的随机模型。对于每一个地震（除了帝王谷），我们认为这两个倾向和走滑分布。在每种情况下，我们使用1-D随机模型。对于这四次地震，我们表明，平均功率谱的原始，也就是说，非插值，数据遵循幂律行为的标度指数范围从0.78到1.71。对于这四次地震，我们发现非高斯概率定律，即Levy定律，更适合于再现滑动振幅分布中嵌入的空间变异性的主要特征，包括大波动的存在和频率。由于粗糙体通常被定义为断层上具有大滑动值的区域，因此随机模型将允许预测和模拟断层表面上粗糙体的空间分布。Levy参数的值从一个地震到另一个地震是不同的。假定北岭地震的倾向和走滑的不均匀性在空间上呈各向同性分布，我们还计算了一个二维随机模型。在一维分析中得出的主要结论仍然适用于二维模型。四次地震的结果表明，滑动空间复杂性的一些特征是普遍的，可以相应地建模。如果这被证明是正确的，这将意味着，空间变异性和长期的相关性的滑移或预应力空间分布可以描述的帮助下，五个参数：一个比例指数控制的空间相关性和四个参数的Levy分布约束的空间变异性。
SUMMARY
Finite-fault source inversions reveal the spatial complexity of earthquake slip or pre-stress distribution over the fault surface. The basic assumption of this study is that a stochastic model can reproduce the variability in amplitude and the long-range correlation of the spatial slip distribution. In this paper, we compute the stochastic model for the source models of four earthquakes: the 1979 Imperial Valley, the 1989 Loma Prieta, the 1994 Northridge and 1995 Hyogo-ken Nanbu (Kobe). For each earthquake (except Imperial Valley), we consider both the dip and strike slip distributions. In each case, we use a 1-D stochastic model. For the four earthquakes, we show that the average power spectra of the raw, that is, non-interpolated, data follow a power-law behaviour with scaling exponents that range from 0.78 to 1.71. For the four earthquakes, we have found that a non-Gaussian probability law, that is, the Levy law, is better suited to reproduce the main features of the spatial variability embedded in the slip amplitude distribution, including the presence and frequency of large fluctuations. Since asperities are usually defined as regions with large slip values on the fault, the stochastic model will allow predicting and modelling the spatial distribution of the asperities over the fault surface. The values of the Levy parameters differ from one earthquake to the other. Assuming an isotropic spatial distribution of heterogeneity for the dip and the strike slip of he Northridge earthquake, we also compute a 2-D stochastic model. The main conclusions reached in the 1-D analysis remain appropriate for the 2-D model. The results obtained for the four earthquakes suggest that some features of the slip spatial complexity are universal and can be modelled accordingly. If this is proven correct, this will imply that the spatial variability and the long-range correlation of the slip or pre-stress spatial distribution can be described with the help of five parameters: a scaling exponent controlling the spatial correlation and the four parameters of the Levy distribution constraining the spatial variability.