Source inversion for estimating the continuous slip distribution on a fault—introduction of Green's functions convolved with a correction function to give moving dislocation effects in subfaults
Source inversion for estimating the continuous slip distribution on a fault—introduction of Green's functions convolved with a correction function to give moving dislocation effects in subfaults
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DOI：
10.1046/j.1365-246x.2002.01669.x
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发表时间：
2002-08
影响因子：
2.8
通讯作者：
H. Sekiguchi;K. Irikura;T. Iwata
中科院分区：
文献类型：
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作者：
H. Sekiguchi;K. Irikura;T. Iwata
为了更准确地获得有关地震破裂物理的知识，并为近源地震动模拟获得可靠的震源过程，我们引入了一种卷积方法，该方法将矩形区域上移动的位错对合成点源的影响引入到计算用于波形反演的单元源波中。因此，在波形反演中充分考虑了整个断裂区的破裂方向性效应。利用该技术反演的破裂过程在次断层内部具有连续的滑移分布。由于每个子断层内部的破裂传播效应是分离的，因此每个子断层的矩释放历史直接反映了子断层上的滑动时间函数。这种方法的有效性基于如下近似：当两个点源之间的距离远小于两个点源到观测站之间的距离时，经过相位校正后，两个点源的格林函数大致相同。通过数值试验，找出了该技术有效应用的条件。我们将这一技术应用于1995年兵库县南部地震震源过程的强震记录波形反演中。两种反演结果的力矩释放分布的整体特征是相似的，一种是用点源单元波形反演的，另一种是考虑各子断层内部有限运动位错效应的单元源波反演的。然而，细节是不同的，如总力矩释放局部极大值的位置不同。最终滑移速度与最大滑移速度呈正相关。
Summary In order to obtain knowledge concerning the physics of earthquake rupturing more precisely and to obtain reliable source process for near-source ground motion simulation, we introduced a convolution method that incorporates the effect of a moving dislocation over a rectangular area to a synthetic point source into computing the element source waves for the waveform inversion. Therefore, the rupture directivity effect over the entire fault area is considered fully in the waveform inversion. The rupture process inverted using this technique has a continuous slip distribution inside the subfaults. The moment release history obtained for each subfault directly reflects a slip time function on the subfault because the rupture propagation effect inside each subfault is separated. The validity of this technique is based on the following approximation: the Green's functions from two point sources are approximately the same after a phase correction when the distances between two point sources is much smaller than the distance between the sources and an observation station. The condition for valid usage of this technique has been found through numerical tests. We applied this technique in the waveform inversion of strong motion records for the source process of the 1995 Hyogo-ken Nanbu earthquake. The global characteristics of moment release distributions are similar between two inversion results; one inverted with point-source element waveforms and the other with element source waves considering the finite moving dislocation effects inside each subfault. However, the details are different, e.g. the locations of local maxima of the total moment release are different between these inversion results. A positive correlation between final slip and peak slip velocity is observed.