Numerical simulation of recurrence of asperity rupture in the Sanriku region, northeastern Japan
Numerical simulation of recurrence of asperity rupture in the Sanriku region, northeastern Japan
复制标题
DOI：
10.1029/2007jb005515
复制
发表时间：
2008-06
影响因子：
--
通讯作者：
N. Kato
中科院分区：
文献类型：
--
作者：
N. Kato
[1]本文对日本东北三陆地区的大地震和地震滑动的复发进行了数值模拟研究，该地区太平洋板块俯冲到北方本州之下，大约每100年发生一次8级地震。假设板界面上的摩擦服从速率和状态相关的摩擦法，并估计摩擦法的本构参数的空间分布，使模拟的滑动历史模拟从地震和大地测量观测估计。通过引入两个具有速度减弱摩擦特性的大粗糙体，可以模拟类似于1968年十胜冲地震（Mw = 8.2）和1994年三陆冲地震（Mw = 7.7）的地震。前者打破了两个大的粗糙体，后者打破了其中一个。两次模拟大震的破裂起始位置几乎相同，成核过程也相似。引入两个较小的凸体来代表较小的地震。其中一个小的凹凸是1994年三陆冲地震的最大余震（Mw = 6.9），它位于1994年主震区的向西，发生在主震后10 d。目前的模拟表明，最大的余震是由震后滑动传播引起的应力触发的。在模拟中，震后滑动强度最大的区域位于主震滑动区和最大余震滑动区之间，这与1994年三陆冲地震的震后滑动GPS数据分析结果一致。地震和地震过程的一些重要特征，从观测估计，在模型中再现。这表明，空间上的不均匀摩擦性能的板界面上，可以在一定程度上估计模型结果和观测数据之间的比较。
[1] A numerical simulation study is presented for the recurrence of great earthquakes and aseismic sliding in the Sanriku region, northeastern Japan, where the Pacific Plate subducts beneath northern Honshu and M8 class earthquakes have occurred approximately every 100 years. The friction on the plate interface is assumed to obey a rate- and state-dependent friction law, and the spatial distribution of constitutive parameters of the friction law is estimated, so that the simulated slip histories mimic those estimated from seismic and geodetic observations. By introducing two large asperities that have velocity-weakening frictional properties, earthquakes similar to the 1968 Tokachi-oki earthquake (Mw = 8.2) and the 1994 Sanriku-oki earthquake (Mw = 7.7) can be modeled. The former broke both the large asperities, and the latter broke one of them. The ruptures of the two simulated large earthquakes started from almost the same location, and their nucleation processes are similar to each other. Two smaller asperities were introduced to represent smaller earthquakes. One of the small asperities is for the largest aftershock (Mw = 6.9) of the 1994 Sanriku-oki earthquake, which was located westward from the 1994 main shock area and took place 10 d after the main shock. The present simulation suggests that the largest aftershock was triggered by stress caused by propagation of postseismic sliding. In the simulation, the area of greatest intensity of postseismic sliding is located in the region between the main shock slip area and the largest aftershock area, which is consistent with the estimation from GPS data analyses for the postseismic sliding of the 1994 Sanriku-oki earthquake. Some important characteristics of seismic and aseismic processes, as estimated from observations, are reproduced in the model. This suggests that spatially nonuniform frictional properties on the plate interface can be estimated to some extent by comparison between model results and observed data.