Abstract

The paper presents the studies of the Khuvsgul earthquake on January 11, 2021 at 21:32 UTC (January 12, 2021 at 05:32 local time), M_W = 6.7, M_L = 6.9, and the seismicity structure in the aftershock period for the Altai-Sayan mountain region and the Baikal rift zone, where the epicenter of this earthquake was located. Two faults are seismically activated, diverging from the southern end of the aftershock area at an acute angle: one in the northeast and one in the northwest direction, as well as transverse faults between them. According to the epicenter position and studies of the source area by other authors, the main event corresponds to the northeastern fault, and large aftershocks occurred at the junction of the northwestern fault with transverse faults feathering from the east. The main event was immediately followed by a series of large aftershocks, the strongest of which occurred on March 31, 2021 with M_L = 6.2 and on May 3, 2021 with M_L = 6.4. Spatial changes in the seismic regime of the aftershock region led to the predominant activity of its southern end. The junction area of the collisional structures of the Altai–Sayan folded zone and the rift structures of the Baikal depressions system is distinguished in seismicity as a block structure with increased seismicity near the block boundaries. First of all, these are the Tuva-Mongolian block and the eastern part of the Sayano-Tuva block. After the Khuvsgul earthquake of 2021, a block structure with the activation of the epicentral zones of the 1991 Busingol earthquake, the 2011–2012 Tuva earthquakes, and other structures seismically active until 2021 has increased seismic activity. It is proved that the 2014 Khuvsgul earthquake occurred under the basin of the same name and is associated with other faults than the 2021 earthquake and is not a direct precursor of the 2021–2022 activation.

中文翻译：

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2021 年 1 月 12 日库苏古尔地震，ML = 6.9，位于图瓦-蒙古地块的地震活动结构中

摘要

论文介绍了 2021 年 1 月 11 日 21:32 UTC（当地时间 2021 年 1 月 12 日 05:32）Khuvsgul 地震的研究，_{MW =} 6.7，ML = 6.9，以及余震期间的地震活动结构此次地震震中位于阿尔泰-萨彦岭地区和贝加尔湖裂谷带。两条断层被地震激活，从余震区南端以锐角分叉：一条在东北方向，一条在西北方向，以及它们之间的横向断层。根据震中位置和其他作者对震源区的研究，主震对应于东北断裂，较大的余震发生在西北断裂与东伸横断层的交汇处。主要事件之后立即发生了一系列大型余震，其中最强的余震发生在2021年3月31日，_ML = 6.2，和2021年5月3日，_ML = 6.4。余震区地震区的空间变化导致了其南端的主要活动。阿尔泰—萨彦褶皱带碰撞构造与贝加尔湖凹陷系统裂谷构造交界处的地震活动特征为块体构造，块体边界附近地震活动性增强。首先是图瓦-蒙古地块和萨亚诺-图瓦地块的东部。 2021 年库苏古尔地震后，随着 1991 年布辛戈尔地震、2011-2012 年图瓦地震以及其他在 2021 年之前地震活跃的结构的震中区的激活，块状结构的地震活动有所增加。事实证明，2014年Khuvsgul地震发生在同名盆地之下，并且与2021年地震以外的其他断层有关，并且不是2021-2022年地震活动的直接前兆。