Study on strong ground motion generated from dynamic rupture model

在近断层强地面运动模拟中，需要建立物理上合理的震源模型。Nakamura和Miyatake(2000)提出了一个基于动态破裂模型的滑动速率时间函数的近似表达式，并说明了如何利用滑动分布或运动学信息来估计上述公式的参数。Miyatake等人。(2003)已应用于几种粗糙的典型简化故障模型，并讨论了如何确定近似表达式的参数。在这篇手稿中，为了评估我们的近似函数，我们将其应用于过去的地震，2001年的庆应地震，以评估我们的方法。将近似时间函数与动态模型的时间函数进行了比较，结果令人满意。由我们的近似模拟产生的近场台站的波形与由动力学模型产生的波形很好地吻合。我们基于动态模型的功能将有助于从可能的破裂场景中进行准确的模拟。我们还研究了地震的动态破裂过程，并估计了动力学参数。首先，通过对近场强地面运动资料和远震波形资料的反演，研究了地震滑动的时空分布，即运动学模型。其次，利用所建立的运动学模型，重建了受约束的动力学模型。DC的分布也是由倒转滑移率时间函数估计的(Mikumo等人，2003)，发现其小于70厘米。我们发现，动力学参数具有很强的异质性。存在两个凹凸不平的地方。第一个微凸体的峰值应力降约为20 Mpa，第二个微凸体的峰值应力降为10 Mpa。在两个凹凸体之间存在很低的或负应力降区。强度过剩和断裂能分布也是不均匀的。

In near fault strong ground motion simulation, it is desired to construct physically reasonable source modeling. Nakamura and Miyatake (2000) have proposed an approximate expression of slip rate time function based on dynamic rupture model.We also showed how to estimate the parameters of the above formula by using the slip-distribution or the kinematic information. Miyatake et al. (2003) have applied to the typical but simplified fault models with several asperities and discussed how to fix the parameters of the approximate expression. In this manuscript, in order to evaluate our approximate function, we apply it to the past earthquake, the 2001 Geiyo earthquake in order to evaluate our method. Comparison between the approximate time functions and those of dynamic model are satisfactory. The waveforms at nearfield stations generated from our approximate modeling fit those from dynamic model very well. Our functions based on dynamic model will help accurate simulation from a probable rupture scenario. We also investigate a dynamic rupture process of the earthquake and estimate the dynamic parameters. Firstly, the space-time distribution of slip of the earthquake, i.e., the kinematic model, was investigated by inverting the nearfield strong ground motion data and teleseismic waveform data. Secondly, we reconstruct a dynamic model in constraint with the above kinematic model. The distribution of Dc is also estimated from the inverted slip rate time functions (Mikumo et al., 2003) and found to be less than 70cm. We found that dynamic parameters are very heterogeneous. There exists two asperities. The peak stress drop on the first asperity is about 20MPa, and 10MPa on the second one. Very low or negative stress drop zone is found between two asperities. The strength excess, and fracture energy distribution are also heterogeneous.