2021 年 9 月 6 日在萨彦主断层(东西伯利亚)的一个弱活动地段发生的托法拉里亚 5.4 级地震

IF 2.6 2区 地球科学 Q2 GEOSCIENCES, MULTIDISCIPLINARY
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引用次数: 0

摘要

我们详细研究了 2021 年 9 月 6 日发生在东萨彦山地区的 5.4 级 Tofalaria 地震,该地区的地震活动水平较低。一方面,由于对该地区地壳应力应变场的了解甚少,另一方面,由于该地区与古老的萨彦主断层西北段(萨彦-贝加尔褶皱带与构造稳定的西伯利亚地台之间的构造边界)的关系,我们对该地震事件产生了兴趣。主震及其最大余震(Mw 4.6)的地震力矩张量和次中心深度是根据位于远震距离的地震站计算的中期面波振幅谱反演的。此外,还估算了主震的时空发展特征积分源参数,并确定了断层面。根据区域地震台站记录的体波,确定了截至 2021 年底发生的 31 次 M≥1.8 余震的震源中心。结果表明,托法拉里亚地震是在西南-东北压缩的影响下发生的,在蒙古西部也能观测到这种压缩。最大余震的聚焦机制和余震震中场(22 千米)的东北向延伸表明,主震后应力在以小尺度断层为边界的局部地壳中重新分布。
本文章由计算机程序翻译,如有差异,请以英文原文为准。
The September 6, 2021 MW 5.4 Tofalaria earthquake at a weakly active segment of the Main Sayan fault (Eastern Siberia)

We study in detail the Mw 5.4 September 6, 2021 Tofalaria earthquake occurred in a mountain area of the Eastern Sayan which is characterized by a low level of seismic activity. An interest in the seismic event is caused, on the one hand, by poor knowledge about stress-strain field of the crust in the considered region, and, on the other hand, by its relation to the NW segment of the ancient Main Sayan fault – a structural boundary between the Sayan-Baikal fold belt and the tectonically stable Siberian platform. Seismic moment tensors and hypocentral depths of the mainshock and its largest aftershock (Mw 4.6) are inverted from intermediate-period surface wave amplitude spectra calculated at the stations located at teleseismic distances. Integral source parameters of the mainshock, characterizing its spatio-temporal development, are also estimated and the fault plane is determined. Epicenters of 31 aftershocks with M ≥ 1.8, occurred up to the end of 2021, are constrained from body waves recorded at regional seismic stations. The obtained results show that the Tofalaria earthquake occurred under the influence of the SW-NE compression, which is observed in Western Mongolia. Focal mechanism of the largest aftershock and the NE elongation of the aftershock epicentral field (22 km) indicate stress redistribution after the mainshock in a local crustal volume, bordered by small-scale faults.

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来源期刊
Journal of Structural Geology
Journal of Structural Geology 地学-地球科学综合
CiteScore
6.00
自引率
19.40%
发文量
192
审稿时长
15.7 weeks
期刊介绍: The Journal of Structural Geology publishes process-oriented investigations about structural geology using appropriate combinations of analog and digital field data, seismic reflection data, satellite-derived data, geometric analysis, kinematic analysis, laboratory experiments, computer visualizations, and analogue or numerical modelling on all scales. Contributions are encouraged to draw perspectives from rheology, rock mechanics, geophysics,metamorphism, sedimentology, petroleum geology, economic geology, geodynamics, planetary geology, tectonics and neotectonics to provide a more powerful understanding of deformation processes and systems. Given the visual nature of the discipline, supplementary materials that portray the data and analysis in 3-D or quasi 3-D manners, including the use of videos, and/or graphical abstracts can significantly strengthen the impact of contributions.
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