VISCOELASTIC STRESS TRANSFER BETWEEN 2008 AND 2014 YUTIAN M7 EARTHQUAKES, XINJIANG

doi:10.3969/j.issn.0253-4967.2016.03.011

Abstract

Abstract:

Two earthquakes with magnitude larger than 7.0 occurred in 2008 and 2014 on the southwestern end of the Altyn Tagh Fault, which is located in the northwestern borderland of Tibetan plateau. Occurrences of these two earthquakes provide important insights into regional geodynamics and potential seismic risk. Layered viscoelastic model is employed in the paper to study the interaction between these two events. We find that most of aftershocks were triggered by coseismic stress produced by the 2008 Yutian earthquake, and the effect of this earthquake is insignificant on the occurrence of the 2014 Yutian earthquake. However, stress transfer by viscoelastic relaxation of postseismic deformation is in favor of occurrence of the 2014 Yutian earthquake. The coseismic and postseismic stress transfer produced by the 2014 Yutian earthquake leads to stress increasing on the western segment of the Altyn Tagh Fault. Since the occurrence time of the last major earthquake on the western segment of the Altyn Tagh Fault is tens of years ago, it should have accumulated large moment deficit on the fault segment. The Altyn Tagh Fault should be considered as a fault with high potential seismic risk.

Key words: Yutian earthquake, layered viscoelastic model, ΔCFS, western segment of the Altyn Tagh Fault, potential seismic risk

摘要：

青藏高原西北边缘地区在2008年和2014年先后发生了2次7级以上强震，这2次地震发生在阿尔金断裂带西南端，对于认识区域动力背景和潜在地震危险性有重要意义。文中采用分层黏弹性模型和最大应力策略研究了这2次地震之间的相互关系。计算结果表明，2008年于田地震的同震应力扰动触发了后续的余震活动，该地震产生的同震应力扰动对2014年于田地震的发生影响不显著；但是，此次地震6a后震后变形所导致的应力扰动有利于2014年于田地震的发生。2014年于田地震发生后，阿尔金断裂带西南段上的同震和震后库伦应力显著增加。考虑到阿尔金断裂带西南段上次强震的离逝时间和应力积累-释放过程，该断裂带上的地震危险性值得进一步关注。

关键词: 于田地震, 分层黏弹性模型, 库伦破裂应力, 阿尔金断裂带西南段, 潜在地震危险性

CLC Number:

P315.72⁺7

WANG Hui, CAO Jian-ling, HONG Shun-ying, XU Yue-ren, JING Feng. VISCOELASTIC STRESS TRANSFER BETWEEN 2008 AND 2014 YUTIAN M7 EARTHQUAKES, XINJIANG[J]. SEISMOLOGY AND GEOLOGY, 2016, 38(3): 646-659.

王辉, 曹建玲, 洪顺英, 徐岳仁, 荆凤. 2008年和2014年2次新疆于田M7地震之间的黏弹性应力转移[J]. 地震地质, 2016, 38(3): 646-659.

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