An adjoint data assimilation method for optimizing frictional parameters on the afterslip area
An adjoint data assimilation method for optimizing frictional parameters on the afterslip area
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DOI：
10.5047/eps.2013.08.002
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发表时间：
2013-12
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影响因子：
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通讯作者：
M. Kano;S. Miyazaki;Kosuke Ito;K. Hirahara
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文献类型：
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作者：
M. Kano;S. Miyazaki;Kosuke Ito;K. Hirahara
余震有时会在几天到几年的时间范围内触发后续地震。因此，用估计的摩擦参数模拟余滑的时空演化，有可能预测这种触发地震的发生。为了证明这一想法的可行性，我们考虑了一个平板界面模型，其中后滑移在两个凹凸体之间遵循速率和状态摩擦定律传播，并采用伴随数据同化方法来优化摩擦参数。综合观测数据采样为20天内板块界面上的滑动速度。结果表明：(1)如果数据集不仅包括余滑或加速的早期阶段，而且还包括衰减阶段或减速，则所有摩擦参数都是优化的；(2)调整后的摩擦参数改善了对触发地震时间的预测。
Afterslip sometimes triggers subsequent earthquakes within a timescale of days to several years. Thus, it may be possible to predict the occurrence of such a triggered earthquake by simulating the spatio-temporal evolution of afterslip with estimated frictional parameters. To demonstrate the feasibility of this idea, we consider a plate interface model where afterslip propagates between two asperities following a rate-and-state friction law, and we adopt an adjoint data assimilation method to optimize frictional parameters. Synthetic observation data are sampled as the slip velocities on the plate interface during 20 days. It is found that: (1) all frictional parameters are optimized if the data sets consists not only of the early phase of afterslip or acceleration, but also of the decaying phase or deceleration; and (2) the prediction of the timing of the triggered earthquake is improved by using adjusted frictional parameters.