Pre- and post-seismic slow slip on the plate boundary off Sanriku, NE Japan associated with three interplate earthquakes as estimated from small repeating earthquake data
Pre- and post-seismic slow slip on the plate boundary off Sanriku, NE Japan associated with three interplate earthquakes as estimated from small repeating earthquake data
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DOI：
10.1016/j.tecto.2004.04.015
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发表时间：
2004-07
期刊：
影响因子：
2.9
通讯作者：
N. Uchida;A. Hasegawa;T. Matsuzawa;T. Igarashi
中科院分区：
文献类型：
--
作者：
N. Uchida;A. Hasegawa;T. Matsuzawa;T. Igarashi
利用小型重复地震资料估算了日本东北三陆三陆三次大地震（1989年Mj 7.1、1992年Mj 6.9和1994年Mj 7.6）前后板块边界准静态（慢）滑动的时空变化。采用的小重复地震序列被认为对应于被准静态滑动区包围的小孤立粗糙体的重复破裂，震源的活度反映了准静态滑动率。伴随中等规模地震的小型重复地震似乎在调查的主要地震发生之前就已经激活，活动开始于1989年，1992年和1994年事件发生前6天，2天和8个月。这些结果表明，这些大地震震源附近的准静态滑动在主震前加速，导致主震的陡岩处应力集中。这一观点得到了以下事实的支持：震中（初始断裂的位置）和准静态滑动加速的区域都位于主震凸起的同一侧。在1994年的余震活动和1989年（Mj 7.1）和1992年（Mj 6.9）的地震群中，还发现了离三陆地区的准静态滑动加速度迁移。目前的研究结果表明，准静态滑动可能在这些大地震的发生中发挥了至关重要的作用，并有助于余震和板块边界的群活动。
The spatio-temporal variation of quasi-static (slow) slip on the plate boundary before and after three major earthquakes (Mj 7.1 in 1989, Mj 6.9 in 1992, and Mj 7.6 in 1994) off Sanriku, northeastern Japan, is estimated using small repeating earthquake data. The small repeating earthquake sequence employed is considered to correspond to repeated rupture of a small isolated asperity surrounded by a quasi-static slipping area, and the activity of the source reflects the quasi-static slip rate. Small repeating earthquakes accompanying moderate-sized events appear to have been activated prior to the major events under investigation, with activity starting 6 days, 2 days, and 8 months before the occurrence of the 1989, 1992, and 1994 events. These results indicate that the quasi-static slip near the hypocenters of these major earthquakes was accelerated prior to the main shocks, causing stress concentration at the asperities responsible for the main shocks. This idea is supported by the fact that both the epicenters (locations of initial breaks) and areas where quasi-static slip was accelerated were located on the same side of the main-shock asperities. Migration of quasi-static slip acceleration in the off-Sanriku region was also identified, apparent in the aftershock activity of the 1994 event and the earthquake swarms including the 1989 (Mj 7.1) and 1992 (Mj 6.9) events. The present results reveal that quasi-static slip may have played a crucial role in the occurrence of these large earthquakes, as well as contributing to aftershock and swarm activity on the plate boundary.