THE 2022 M6.8 LUDING EARTHQUAKE: A COMPLICATED EVENT BY FAULTING OF THE MOXI SEGMENT OF THE XIANSHUIHE FAULT ZONE

doi:10.3969/j.issn.0253-4967.2022.06.017

Abstract

Abstract:

The September 5, 2022, M6.8 Luding earthquake occurred along the southeastern segment of the Xianshuihe fault zone. Tectonics around the epicenter area is complicated and several faults had been recognized. Focal mechanisms of the main shock and inversions from earthquake data suggest that the earthquake occurred on a northwest-trending, steeply dipping strike-slip fault, which is consistent with the strike and slip of the Xianshuihe fault zone. We conducted a field investigation along the fault sections on both sides of the epicenter immediately after the earthquake. NW-trending fractures that were recognized as surface ruptures during the earthquake, and heavy landslides along the fault section between Ertaizi-Aiguocun village were observed during the field investigations. There are no surface ruptures developed along the fault sections north of the epicenter and south of Aiguocun village. Thus it can be concluded that there is a 15.5km-long surface rupture zone developed along the Moxi Fault(the section between Ertaizi and Aiguo village). The surface rupture zone trends northwest and shows a left-lateral strike slip, which is consistent with the strike and motion constrained by the focal mechanism. The coseismic displacements were measured to 20~30cm. Field observations, focal fault plane, distribution of the aftershocks, GNSS, and InSAR observation data suggest that the seismogenic structure associated with the M6.8 Luding earthquake is the Moxi Fault that belongs to the southeastern segment of the Xianshuihe fault zone. Slip along the segment south of the epicenter generated this earthquake, and also triggered slip along a northeast-trending fault and the northwestern section of the Moxi Fault in the epicenter. So, the M6.8 Luding earthquake is an event that is nucleated on the section south of the epicenter and then triggered an activity of the whole fault segment.

Key words: the Luding M6.8 earthquake, coseismic surface rupture, seismogenic structure, the Xianshuihe fault zone, the Moxi Fault

摘要：

2022年9月5日12时52分, 川滇活动地块东边界的四川泸定地区发生6.8级强烈地震。在震中以北15km、以南25km的范围内开展震后现场考察, 发现湾东村、幸福村、爱国村一带的磨西断裂沿线存在同震地表破裂迹象, 而在震中以北、爱国村以南断裂通过的位置没有发育同震地表破裂。野外调查获得的同震地表破裂走向为320°~355°, 运动性质为左旋走滑, 位移量为20~30cm, 运动性质和走向与震源机制解获得的结果一致。深入分析认为, 本次四川泸定6.8级地震的同震地表破裂主要发育在泸定县磨西镇二台子以南-石棉县王岗坪乡爱国村之间, 长度为15.5km。根据野外地质调查结果, 并综合地震反演和形变观测已有结果等判定, 四川泸定6.8级地震的发震构造为鲜水河断裂的南东段, 即磨西断裂。结合余震分布时空演化特征分析进一步揭示, 以磨西断裂二台子-新民乡段为主震破裂段的运动导致了此次6.8级地震的发生, 并触发了震中以北的南门关-两河口段断裂的活动。泸定6.8级地震是一次主震破裂段发动、其后全段参与的较为复杂的事件。

关键词: 泸定6.8级地震, 地表破裂, 发震构造, 鲜水河断裂带, 磨西断裂

CLC Number:

P315.2

LI Chuan-you, SUN Kai, MA Jun, LI Jun-jie, LIANG Ming-jian, FANG Li-hua. THE 2022 M6.8 LUDING EARTHQUAKE: A COMPLICATED EVENT BY FAULTING OF THE MOXI SEGMENT OF THE XIANSHUIHE FAULT ZONE[J]. SEISMOLOGY AND GEOLOGY, 2022, 44(6): 1648-1666.

李传友, 孙凯, 马骏, 李俊杰, 梁明剑, 房立华. 四川泸定6.8级地震--鲜水河断裂带磨西段局部发起、全段参与的一次复杂事件[J]. 地震地质, 2022, 44(6): 1648-1666.

Figures/Tables 8

Fig. 1 Map showing the location of the epicenter of the M6.8 Luding earthquake and major faults around the epicenter.

Fig. 2 Maps showing field observation sites, fault geometry and aftershock distribution.

Fig. 3 Photographs showing fault expression and geomorphic features of the Moxi Fault along the section around and north of the epicenter.

Fig. 4 Co-seismic deformation along the Moxi Fault around Wandong village.

Fig. 5 Co-seismic deformation along the Moxi Fault from the mountain pass of Menghugang to Xingfucun village.

Fig. 6 Co-seismic deformation and geomorphic features along the Moxi Fault around Aiguo village.

Fig. 7 Spatio-temporal evolution of the aftershock distribution associated with the MS6.8 Luding earthquake.

Fig. 8 Major active faults and strong earthquakes(M≥5.0)on the eastern margin of Tibetan plateau.

References 55

[1]	陈博, 李振洪, 黄武彪, 等. 2022. 2022年四川泸定 M_W6.6 地震诱发地质灾害空间分布及影响因素[J]. 地球科学与环境学报, 44(6): 971-985.
	CHEN Bo, LI Zhen-hong, HUANG Wu-biao, et al. 2022. Spatial distribution and influencing factors of geohazards induced by the 2022 M_W6.6 Luding(Sichuan, China)earthquake[J]. Journal of Earth Sciences and Environment, 44(6): 971-985. (in Chinese)
[2]	陈桂华, 安艳芬, 江国焰. 2018. 鲜水河活动断裂(雪门坎至石棉段)分布图(1:50 000)及说明书[M]. 北京: 地震出版社.
	CHEN Gui-hua, AN Yan-fen, JIANG Guo-yan. 2018. Map of the Xianshuihe Fault Zone and Descriptions (1:50 000)[M]. Seismological Press, Beijing. (in Chinese)
[3]	陈桂华, 闵伟, 宋方敏, 等. 2011. 从1786年磨西地震看地震地表破裂带在不同地貌区的保存[J]. 地震地质, 33(4): 804-817.
	CHEN Gui-hua, MIN Wei, SONG Fang-min, et al. 2011. Preservation of co-seismic surface rupture in different geomorphological settings from the study of the 1786 Moxi earthquake[J]. Seismology and Geology, 33(4): 804-817. (in Chinese)
[4]	陈九辉, 刘启元, 李顺成, 等. 2009. 汶川 M_S8.0 地震余震序列重新定位及其地震构造研究[J]. 地球物理学报, 52(2): 390-397.
	CHEN Jiu-hui, LIU Qi-yuan, LI Shun-cheng, et al. 2009. Seismotectonic study by relocation of the Wenchuan M_S8.0 earthquake sequence[J]. Chinese Journal of Geophysics, 52(2): 390-397. (in Chinese) DOI URL
[5]	邓起东, 张培震, 冉勇康, 等. 2002. 中国活动构造基本特征[J]. 中国科学(D辑), 32(12): 1020-1030.
	DENG Qi-dong, ZHANG Pei-zhen, RAN Yong-kang, et al. 2002. Basic characteristics of active tectonics in China[J]. Science in China(Ser D), 32(12): 1020-1030. (in Chinese)
[6]	邓天岗, 龙德雄, 冯元保. 1986. 1786年四川康定地震[J]. 中国地震, 2(3): 98-99.
	DENG Tian-gang, LONG De-xiong, FENG Yuan-bao. 1986. The 1786 Kangding earthquake in Sichuan[J]. Earthquake Research in China, 2(3): 98-99. (in Chinese)
[7]	范文纪. 1982. 贡嘎山的地质构造基础和冰川地貌特征[J]. 成都科技大学学报, (3): 19-33.
	FAN Wen-ji. 1982. Geological structure foundation and glacial geomorphic characteristics of the Gongga Mountain[J]. Journal of Chengdu University of Science and Technology, (3): 19-33. (in Chinese)
[8]	房立华, 吴建平, 苏金蓉, 等. 2018. 四川九寨沟 M_S7.0 地震主震及其余震序列精定位[J]. 科学通报, 63(7): 649-662.
	FANG Li-hua, WU Jian-ping, SU Jin-rong, et al. 2018. Relocation of mainshock and aftershock sequence of the M_S7.0 Sichuan Jiuzhaigou earthquake[J]. Chinese Science Bulletin, 63(7): 649-662. (in Chinese)
[9]	冯嘉辉, 陈立春, 王虎, 等. 2021. 大凉山断裂带北段石棉断裂的古地震[J]. 地震地质, 43(1): 53-71.
	FENG Jia-hui, CHEN Li-chun, WANG Hu, et al. 2021. Paleoseismological study on the Shimian Fault in the northern section of the Daliangshan fault zone[J]. Seismology and Geology, 43(1): 53-71. (in Chinese)
[10]	何宏林, 池田安隆, 何玉林, 等. 2008. 新生的大凉山断裂带--鲜水河-小江断裂系中段的截弯取直[J]. 中国科学(D辑), 38(5): 564-574.
	HE Hong-lin, IKEDA Yasutaka, HE Yu-lin, et al. 2008. Newly generated Daliangshan fault zone: Shortcutting on the central section of Xianshuihe-Xiaojiang fault system[J]. Science in China(Ser D), 38(5): 564-574. (in Chinese)
[11]	李东雨, 陈立春, 梁明剑, 等. 2017. 鲜水河断裂带乾宁段古地震事件与大震复发行为[J]. 地震地质, 39(4): 623-643.
	LI Dong-yu, CHEN Li-chun, LIANG Ming-jian, et al. 2017. Holocene paleoseismologic record and rupture behavior of large earthquake on the Xianshuihe Fault[J]. Seismology and Geology, 39(4): 623-643. (in Chinese)
[12]	李天袑, 杜其方, 游泽李, 等. 1997. 鲜水河活动断裂带及强震危险性评估[M]. 成都: 成都地图出版社:1-224.
	LI Tian-shao, DU Qi-fang, YOU Ze-li, et al. 1997. The Xianshuihe Fault Zone and Risk Assessment of Strong Earthquake along It [M]. Chengdu Cartographic Publishing House, Chengdu: 1-224 (in Chinese)
[13]	梁明剑, 陈立春, 冉勇康, 等. 2020. 鲜水河断裂带雅拉河段晚第四纪活动性[J]. 地震地质, 42(2): 513-525.
	LIANG Ming-jian, CHEN Li-chun, RAN Yong-kang, et al. 2020. Late-Quaternary activity of the Yalahe Fault of the Xianshuihe fault zone, eastern margin of the Tibet plateau[J]. Seismology and Geology, 42(2): 513-525. (in Chinese)
[14]	龙德雄, 邓天岗. 1990. 1786年康定地震形变特征的初步研究[J]. 地震研究, 13(1): 51-60.
	LONG De-xiong, DENG Tian-gang. 1990. A preliminary study on the 1786 Kangding earthquake deformation characteristics[J]. Journal of Seismological Research, 13(1): 51-60. (in Chinese)
[15]	钱洪, Allen C R, 罗灼礼, 等. 1988. 全新世以来鲜水河断裂的活动特征[J]. 中国地震, 4(2): 9-18.
	QIAN Hong, Allen C R, LUO Zhuo-li, et al. 1988. The active characteristics of the Xianshuihe Fault in Holocene[J]. Earthquake Research in China, 4(2): 9-18. (in Chinese)
[16]	冉勇康, 陈立春, 程建武, 等. 2008. 安宁河断裂冕宁以北晚第四纪地表变形与强震破裂行为[J]. 中国科学(D辑), 38(5): 543-554.
	RAN Yong-kang, CHEN Li-chun, CHENG Jian-wu, et al. 2008. Late Quaternary surface deformation and rupture behavior of strong earthquake on the segment north of Mianning of the Anninghe Fault[J]. Science in China(Ser D), 38(5): 543-554. (in Chinese)
[17]	邵志刚, 马宏生, 张浪平, 等. 2013. 2010年玉树 M_S7.1 地震同震破裂、余震分布特征及其与构造的关系[J]. 地球物理学报, 56(11): 3800-3810.
	SHAO Zhi-gang, MA Hong-sheng, ZHANG Lang-ping, et al. 2013. The characteristics of co-seismic slip and aftershocks distribution of the M_S7.1 earthquake at Qinghai Yushu in 2010 and its relationship with tectonics[J]. Chinese Journal of Geophysics, 56(11): 3800-3810. (in Chinese)
[18]	四川省地震资料编辑组. 1980. 四川地震资料汇编[M]. 成都: 四川人民出版社.
	Editorial Group for Earthquake Data of Sichuan Province. 1980. Collection of Earthquake Data of Sichuan Province[M]. Sichuan People’s Publishing House, Chengdu. (in Chinese)
[19]	唐荣昌, 韩渭滨. 1993. 四川活动断裂与地震[M]. 北京: 地震出版社, 附件: 12-20.
	TANG Rong-chang, HAN Wei-bin. 1993. Active Faults and Earthquakes in Sichuan Province [M]. Seismological Press, Beijing: appendix: 12-20 (in Chinese)
[20]	王碧泉, 王春珍. 1983. 余震序列的时空特征[J]. 地震学报, 5(4): 383-396.
	WANG Bi-quan, WANG Chun-zhen. 1983. Temporal and spatial features of aftershock sequences[J]. Acta Seismologica Sinica, 5(4): 383-396. (in Chinese)
[21]	王新民, 裴锡瑜. 1988. 对1786年康定-泸定磨西间7¾级地震的新认识[J]. 中国地震, 4(1): 110-117.
	WANG Xin-min, PEI Xi-yu. 1988. Some new points of view on the 1786 earthquake(M=7¾)occurring in the area between Kangding and Moxi, Luding, Sichuan Province[J]. Earthquake Research in China, 4(1): 110-117. (in Chinese)
[22]	闻学泽. 2000. 四川西部鲜水河-安宁河-则木河断裂带的地震破裂分段特征[J]. 地震地质, 22(3): 239-249.
	WEN Xue-ze. 2000. Character of rupture segmentation of the Xianshuihe-Anninghe-Zemuhe fault zone, western Sichuan[J]. Seismology and Geology, 22(3): 239-249. (in Chinese)
[23]	闻学泽, Allen C R, 罗灼礼, 等. 1989. 鲜水河全新世断裂带的分段性、几何特征及其地震构造意义[J]. 地震学报, 11(4): 362-372.
	WEN Xue-ze, Allen C R, LUO Zhuo-li, et al. 1989. Segmentation, geometric features, and their seismotectonic implications for the Holocene Xianshuihe fault zone[J]. Acta Seismologica Sinica, 11(4): 362-372. (in Chinese)
[24]	闻学泽, 范军, 易桂喜, 等. 2008. 川西安宁河断裂上的地震空区[J]. 中国科学(D 辑), 38(7): 797-807.
	WEN Xue-ze, FAN Jun, YI Gui-xi, et al. 2008. A seismic gap on the Anninghe Fault in western Sichuan, China[J]. Science in China(Ser D), 38(7): 797-807. (in Chinese)
[25]	闻学泽, 徐锡伟, 郑荣章, 等. 2001. 磨西断裂的晚第四纪活动性与大地震复发间隔 [G]//卢演俦主编. 新构造与环境. 北京: 地震出版社: 255-266.
	WEN Xue-ze, XU Xi-wei, ZHENG Rong-zhang, et al. 2001. Late Quaternary activity and large earthquake recurrence along the Moxi Fault [G]//LU Yan-chou(ed). The Neo-tectonics and Environment. Seismological Press, Beijing: 255-266 (in Chinese)
[26]	徐晶, 邵志刚, 刘静, 等. 2019. 川滇菱形块体东边界库仑应力演化及强震发生概率估算[J]. 地球物理学报, 62(11): 4189-4213.
	XU Jing, SHAO Zhi-gang, LIU Jing, et al. 2019. Coulomb stress evolution and future earthquake probability along the eastern boundary of the Sichuan-Yunnan block[J]. Chinese Journal of Geophysics, 62(11): 4189-4213. (in Chinese)
[27]	徐泰然, 戴丹青, 杨志高, 等. 2022. 2022年9月5日四川泸定6.8级地震初步研究结果[J]. 中国地震, 38(3): 412-424.
	XU Tai-ran, DAI Dan-qing, YANG Zhi-gao, et al. 2022. Preliminary study of emergency production and source parameters of the M6.8 earthquake on September 05, 2022 in Luding, Sichuan Province[J]. Earthquake Research in China, 38(3): 412-424. (in Chinese)
[28]	易桂喜, 龙锋, 闻学泽, 等. 2015. 2014年11月22日康定M6.3地震序列发震构造分析[J]. 地球物理学报, 58(4): 1205-1219.
	YI Gui-xi, LONG Feng, WEN Xue-ze, et al. 2015. Seismological structure of the M6.3 Kangding earthquake sequence on 22 Nov. 2014, southwestern China[J]. Chinese Journal of Geophysics, 58(4): 1205-1219. (in Chinese)
[29]	张广伟, 雷建设. 2013. 四川芦山7.0级强震及其余震序列重定位[J]. 地球物理学报, 56(5): 1764-1771.
	ZHANG Guang-wei, LEI Jian-she. 2013. Relocation of Lushan, Sichuan strong earthquake(M_S7.0) and its aftershocks[J]. Chinese Journal of Geophysics, 56(5): 1764-1771. (in Chinese)
[30]	张培震, 邓起东, 张国民, 等. 2003. 中国大陆的强震活动与活动地块[J]. 中国科学(D辑), 33(S1): 12-20.
	ZHANG Pei-zhen, DENG Qi-dong, ZHANG Guo-min, et al. 2003. Active tectonic blocks and strong earthquakes in the continent of China[J]. Science in China(Ser D), 33(S1): 12-20. (in Chinese)
[31]	赵翠萍, 陈章立, 郑斯华. 2008. 1998-2003年伽师3次不同类型 M_S6 地震震源破裂过程及短期内余震活动特征[J]. 地球物理学报, 51(4): 1093-1102.
	ZHAO Cui-ping, CHEN Zhang-li, ZHENG Si-hua. 2008. Source rupture process of 3 Jiashi M_S6 events(1998-2003)and its correlation with the aftershock activity[J]. Chinese Journal of Geophysics, 51(4): 1093-1102. (in Chinese) DOI URL
[32]	周荣军, 何玉林, 黄祖智, 等. 2001a. 鲜水河断裂带乾宁-康定段的滑动速率与强震复发间隔[J]. 地震学报, 23(3): 250-261.
	ZHOU Rong-jun, HE Yu-lin, HUANG Zu-zhi, et al. 2001a. The slip rate and recurrence interval of strong earthquake on the Qianning-Kangding segment of the Xianshuihe fault zone[J]. Acta Seismologica Sinica, 23(3): 250-261. (in Chinese)
[33]	周荣军, 何玉林, 杨涛, 等. 2001b. 鲜水河-安宁河断裂带磨西-冕宁段的滑动速率与强震位错[J]. 中国地震, 17(3): 253-262.
	ZHOU Rong-jun, HE Yu-lin, YANG Tao, et al. 2001b. Slip rate and strong earthquake rupture on the Moxi-Mianning segment along the Xianshuihe-Anninghe fault zone[J]. Earthquake Research in China, 17(3): 253-262. (in Chinese)
[34]	周荣军, 雷建成, 黎小刚, 等. 2000. 晚第四纪以来大渡河断裂活动性的地质地貌判据 [C]//陈运泰主编. 中国地震学会第8次学术大会论文摘要集. 北京: 地震出版社: 54.
	ZHOU Rong-jun, LEI Jian-cheng, LI Xiao-gang, et al. 2000. Geology and geomorphic evidence for activity of Daduhe Fault since late Quaternary [C]//CHEN Yun-tai(ed). Collection of Essays for the 8th Academic Conference of the Seismological Society of China. Seismological Press, Beijing: 54 (in Chinese)
[35]	Allen C R, Luo Z L, Qian H, et al. 1991. Field study of a highly active fault zone: The Xianshuihe Fault of southwestern China[J]. Geological Society of America Bulletin, 13: 1178-1199.
[36]	Bai M, Chevalier M L, Leloup P H, et al. 2021. Spatial slip rate distribution along the SE Xianshuihe Fault, eastern Tibet, and earthquake hazard assessment[J]. Tectonics, 40(11): e2021TC006985.
[37]	Burchfiel B C, Chen Z, Liu Y, et al. 1995. Tectonics of the Longmenshan and adjacent regions[J]. International Geology Review, 37(8): 661-735. DOI URL
[38]	Das S, Henry C. 2003. Spatial relation between main earthquake slip and its aftershock distribution[J]. Reviews of Geophysics, 41(3): 1013.
[39]	Gülen L, Pinar A, Kalafat D, et al. 2002. Surface fault breaks, aftershock distribution, and rupture process of the 17 August 1999 İzmit, Turkey, earthquake[J]. Bulletin of the Seismological Society of America, 92(1): 230-244. DOI URL
[40]	Guo R M, Zheng Y, Tian W, et al. 2018. Locking status and earthquake potential hazard along the middle-south Xianshuihe Fault[J]. Remote Sensing, 10:2048. https://doi.org/10.3390/rs10122048. DOI URL
[41]	Harris R A. 1998. Introduction to special section: Stress triggers, stress shadows, and implications for seismic hazard[J]. Journal of Geophysical Research, 103(B10): 24347-24358. DOI URL
[42]	Hu C Z, Yang P X, Liang P, et al. 2015. The Holocene paleoearthquakes on the 2014 Kangding M_S6.3 earthquake faults[J]. Chinese Science Bulletin, 60(23): 2236-2244.
[43]	Jiang G, Wen Y, Liu Y, et al. 2015. Joint analysis of the 2014 Kangding, southwest China, earthquake sequence with seismicity relocation and InSAR inversion[J]. Geophysical Research Letters, 42: 3273-3281. DOI URL
[44]	Li Y, Bürgmann R. 2021. Partial coupling and earthquake potential along the Xianshuihe Fault, China[J]. Journal of Geophysical Research: Solid Earth, 126(7): e2020JB021406.
[45]	Liang M J, Chen L C, Ran Y K, 2020. Abnormal accelerating stress release behavior on the Luhuo segment of the Xianshuihe Fault, southeastern margin of the Tibetan plateau, during the past 3 000 years [J]. Frontiers in Earth Science, 8:274. doi: 10.3389/feart.2020.00274. DOI URL
[46]	Molnar P, Deng Q D. 1984. Faulting associated with large earthquakes and the average rate of deformation in central and eastern Asia[J]. Journal of Geophysical Research, 89(B7): 6203-6227. DOI URL
[47]	Ozawa S, Ando R. 2021. Mainshock and aftershock sequence simulation in geometrically complex fault zones[J]. Journal of Geophysical Research: Solid Earth, 126(2): e2020JB020865.
[48]	Qiao X, Zhou Y. 2021. Geodetic imaging of shallow creep along the Xianshuihe Fault and its frictional properties[J]. Earth and Planetary Science Letters, 567: 117001. DOI URL
[49]	Toda S, Lin J, Meghraoui M, et al. 2008. 12 May 2008 M=7.9 Wenchuan, China, earthquake calculated to increase failure stress and seismicity rate on three major fault systems[J]. Geophysical Research Letters, 35: L17305. doi: 10.1029/2008GL034903. DOI URL
[50]	Wang E Q, Burchfiel B C, Royden L H, et al. 1998. Late Cenozoic Xianshuihe-Xiaojiang, Red River, and Dali fault systems of southwestern Sichuan and central Yunnan, China[R]. Geological Society of American, Special Paper, 327: 1-108.
[51]	Wang H, Ran Y K, Chen L C, et al. 2017. Paleoearthquakes on the Anninghe and Zemuhe Fault along the southeastern margin of the Tibetan plateau and implications for fault rupture behavior at fault bends on strike-slip faults[J]. Tectonophysics, 721: 167-178. DOI URL
[52]	Wang H, Ran Y K, Li Y B, et al. 2014. A 3 400-year-long paleoseismologic record of earthquakes on the southern segment of Anninghe Fault along the southeastern margin of the Tibetan plateau[J]. Tectonophysics, 628: 206-217. DOI URL
[53]	Wen X, Ma S, Xu X, et al. 2008. Historical pattern and behavior of earthquake ruptures along the eastern boundary of the Sichuan-Yunnan faulted-block, southwestern China[J]. Physics of the Earth and Planetary Interiors, 168(1-2): 16-36. DOI URL
[54]	Yan B, Lin A M. 2017. Holocene activity and paleoseismicity of the Selaha Fault, southeastern segment of the strike-slip Xianshuihe fault zone, Tibetan plateau[J]. Tectonophysics, 694: 302-318. DOI URL
[55]	Yukutake Y, Lio Y. 2017. Why do aftershocks occur?Relationship between mainshock rupture and aftershock sequence based on highly resolved hypocenter and focal mechanism distributions[J]. Earth, Planets and Space, 69:68. doi: 10.1186/s40623-017-0650-2. DOI URL