Dependence of the Omori‐Utsu law parameters on main shock magnitude: Observations and modeling
Dependence of the Omori‐Utsu law parameters on main shock magnitude: Observations and modeling
复制标题
大森宇津定律参数对主震震级的依赖性：观测和建模
DOI：
--
复制
发表时间：
2007
期刊：
影响因子：
--
通讯作者：
D. Marsan
中科院分区：
文献类型：
--
作者：
S. Hainzl;D. Marsan
[1]我们研究了出现在Omori-Utsu公式λ(t, m) = χ x (t + c)−p中的p与主震震级m的依赖关系，这与主震后t时刻余震λ的频率有关。观察结果表明，p随m显著增加，并形成χ ~ 10αm的标度关系。在这里，我们表明，当考虑到主断层的同震应力非均质性的实际水平时，这些观测结果可以在速率和状态摩擦模型的框架内解释。为了恢复以往和新的余震序列分析中观察到的趋势，我们对模型参数进行了约束。对于大地震（m = 7），同震应力降标准差与均值的比值为几个单位，导致小震级的应力场非常粗糙，而小震级的应力场则平滑得多（m = 2的比值为0.1）。最后，研究了后移对参数p和χ的影响，以突出它可以显著扰动由初始无后移模型得到的p(m)和χ(m)关系。
[1] We examine the dependence on main shock magnitude m of the p and χ parameters appearing in Omori-Utsu formula λ(t, m) = χ × (t + c)−p relating the rate of aftershocks λ at time t after a main shock. Observations point out to a significant increase of p with m, along with a scaling relationship of the form χ ∼ 10αm. Here we show that these observations can be explained within the framework of the rate-and-state friction model when accounting for realistic levels of coseismic stress heterogeneity on the main fault. We constrain the model parameters in order to recover the trends observed in previous and new analyses of aftershock sequences. The expected ratio of the coseismic stress drop standard deviation to its mean is found to be of the order of a few units for large (m = 7) earthquakes, resulting in a very rough stress field at the small scale, while it is much smoother at small magnitudes (ratio ≃ 0.1 at m = 2). Finally, the influence of afterslip on parameters p and χ is studied to highlight the fact that it can significantly perturb the p(m) and χ(m) relations obtained with the initial afterslip-free model.