Mapping of asperities and estimation of spatiotemporal distribution of interplate slip

在本研究中，我们的目标是分析日本东北部太平洋下的板块边界上的锁定和滑动的细节，并了解板间地震的发生机制。主要研究内容有：1.重复地震的分析，2。基于宽频带地震波形资料的中大地震震源过程分析; GPS数据分析，4.利用数值模拟的方法对微凸体的性质进行了研究。重复地震的分析，我们成功地估计了2003年十胜冲地震破裂带周围的板间滑动的时间变化，通过识别从北海道到日本东北部太平洋下的所有部分的重复地震。至于2号。基于地震波形资料的震源过程分析表明，2005年8月16日宫城冲7.2级地震的破裂区与破裂区东南部重叠 ...更多信息 1978年的宫城大地震因此，这意味着位于北部和西部的1978年地震的凹凸体没有破裂，我们的研究指出了对这一地区继续进行仔细观察的重要性。此外，我们对20世纪30年代宫城冲7级以上地震的余震进行了再分析，发现在20世纪30年代宫城冲地震的情况下，三个凸起可能分别滑动了三次。为3. GPS分析表明，2005年宫城地震后，我们检测到了向地震破裂区南部扩展的余震。这一观测结果与地震波形反演分析的结果相一致，北方和西方的凹凸体没有破裂。4的结果。数值模拟分析表明，为了解释在靠近陆地的深部板块边界观测到的后滑移的传播速度，板块边界附近的孔隙压力应该是非常大的。另一方面，为了解释在靠近沟槽的浅板边界中观察到的后滑移的传播速度，不需要像上述情况那样的大孔隙压力。这些结果表明，由于脱水反应而向板块边界供给的水量在深度上发生了变化，或者板块边界附近的渗透系数在深度上发生了变化。如上所述，通过本研究，我们在加深对板间地震发生机制的认识方面取得了实质性成果。少

In this research, we have been aiming to analyze details of lock and slip on the plate boundary under the Pacific Ocean in NE Japan and to understand the generation mechanism of interplate earthquakes. The main research contents are: 1. analysis of repeating earthquakes, 2. analysis of source process of medium ＆ large earthquakes based on broadband seismic waveform data, 3. GPS data analysis, 4. research on the property of asperities by using numerical simulation.According to the result of 1. analysis of repeating earthquakes, we successfully estimated the time variation of interplate slips around the rupture zone of the 2003 Tokachi-oki earthquake, by identifying the repeating earthquakes in all parts of the plate boundary under the Pacific Ocean from Hokkaido to NE Japan. As for the 2. analysis of source process based on seismic waveform data, we showed that the rupture area of Miyagi-oki earthquake (M7.2) on Aug. 16, 2005 is overlapped with the southeastern part of the rupture area … More of the 1978 Miyagi-oki earthquake. So, this means that the asperities of the 1978 earthquake located in the north and west part are left unruptured; our research pointed out the importance of continued and careful observation on this area. Moreover, we conducted reanalysis of aftershocks of Miyagi-oki earthquakes with magnitude >7 in 1930s, and found out that three asperities could have slipped separately, in three times, in the case of 1930s' Miyagi-oki earthquakes. With 3. GPS analysis, after 2005 Miyagi-oki earthquake, we detected the after slip which spread toward south of the rupture area of the event. This observation result corresponds with the result of seismic-waveform inversion analysis; the northern and western asperities are left unruptured. The result of 4. numerical simulation analysis shows that, in order to explain the propagation velocity of the after slip observed in the deep plate boundary close to land, pore pressure around the plate boundary should be extremely large. On the other hand, in order to explain the propagation velocity of the after slip observed in the shallow plate boundary close to the trench, large pore pressure is not necessary like in the case above. These results suggest the depth variation in the amount of water supplied to the plate boundary, which was caused by dehydration reaction, or the depth variation in coefficient of permeability around the plate boundary.As mentioned above, through this research, we have achieved substantial results to enhance understanding of the generation mechanism of interplate earthquakes. Less