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One-off deep crustal earthquake swarm in a stable intracontinental region of the southwestern Korean Peninsula
Physics of the Earth and Planetary Interiors ( IF 2.3 ) Pub Date : 2020-11-01 , DOI: 10.1016/j.pepi.2020.106582
Tae-Kyung Hong , Seongjun Park , Junhyung Lee , Dongchan Chung , Woohan Kim

Abstract A deep crustal strike-slip earthquake swarm that occurred in the intracontinental region of the southwestern Korean Peninsula is investigated. The earthquakes are detected using matched filter analysis. The hypocenters are then refined, showing more than 500 micro to small strike-slip earthquakes concentrated on a fault plane with dimensions of 500 m by 300 m at a depth of ~21 km. The low temperature in the source depth facilitates the seismicity. The earthquake swarm was transiently active for 15 days from 25 April 2020 to 12 May 2020, presenting a high seismicity rate with a Gutenberg-Richter b value of 2.01 (±0.05). The earthquake swarm began in the central area and expanded outward with time. The spatiotemporal seismicity distribution reflects bilateral rupture. The focal mechanism solutions suggest a left-lateral strike-slip fault with a strike of 103.6∘ ± 3.2∘ and a dip of 73.3∘ ± 11.7∘. The spatial distribution of seismicity generally agrees with the focal mechanism solutions. The orientation of the inverted stress field agrees with the ambient stress field, suggesting that the earthquake swarm occurred as a consequence of ambient lithostatic stress loading. Coulomb stress changes suggest that the stress increased in the directions of WNW-ESE and NNE-SSW from the fault. The transiently active earthquake swarm began to occur after the 2011 MW9.0 Tohoku-Oki megathrust earthquake, suggesting a rapid release of accumulated stress in response to changes in the properties of the medium caused by the megathrust earthquake.

中文翻译:

朝鲜半岛西南部陆内稳定区一次性深部地壳地震群

摘要 研究了发生在朝鲜半岛西南部陆内地区的一个深部地壳走滑地震群。使用匹配滤波器分析检测地震。然后对震源进行细化,显示超过 500 次微到小的走滑地震集中在一个断层面上,断层面的尺寸为 500 m x 300 m,深度约为 21 公里。震源深度的低温有利于地震活动。从2020年4月25日至2020年5月12日,地震群短暂活跃了15天,呈现出高地震活动率,Gutenberg-Richter b值为2.01(±0.05)。震群开始于中部地区,并随着时间向外扩展。时空地震活动分布反映了双边破裂。震源机制解表明存在左旋走滑断层,走向为 103.6∘±3.2∘,倾角为 73.3∘±11.7∘。地震活动的空间分布与震源机制解基本一致。反演的应力场方向与环境应力场一致,表明地震群的发生是环境岩石静应力加载的结果。库仑应力变化表明,断层向 WNW-ESE 和 NNE-SSW 方向的应力增加。2011 年 MW9.0 东北-冲特大逆冲地震后,短暂活跃的地震群开始发生,表明累积应力快速释放,以响应特大地震引起的介质性质变化。地震活动的空间分布与震源机制解基本一致。反演的应力场方向与环境应力场一致,表明地震群的发生是环境岩石静应力加载的结果。库仑应力变化表明,断层向 WNW-ESE 和 NNE-SSW 方向的应力增加。2011 年 MW9.0 东北-冲特大逆冲地震后,短暂活跃的地震群开始发生,表明累积应力快速释放,以响应特大地震引起的介质性质变化。地震活动的空间分布与震源机制解基本一致。反演的应力场方向与环境应力场一致,表明地震群的发生是环境岩石静应力加载的结果。库仑应力变化表明,断层向 WNW-ESE 和 NNE-SSW 方向的应力增加。2011 年 MW9.0 东北-冲特大逆冲地震后,短暂活跃的地震群开始发生,表明累积应力快速释放,以响应特大地震引起的介质性质变化。表明地震群的发生是环境岩石静应力加载的结果。库仑应力变化表明,断层向 WNW-ESE 和 NNE-SSW 方向的应力增加。2011 年 MW9.0 东北-冲特大逆冲地震后,短暂活跃的地震群开始发生,表明累积应力快速释放,以响应特大地震引起的介质性质变化。表明地震群的发生是环境岩石静应力加载的结果。库仑应力变化表明,断层向 WNW-ESE 和 NNE-SSW 方向的应力增加。2011 年 MW9.0 东北-冲特大逆冲地震后,短暂活跃的地震群开始出现,表明累积应力快速释放,以响应特大地震引起的介质性质变化。
更新日期:2020-11-01
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