MECHANISM OF THE 2015 PISHAN, XINJIANG, MS6.5 MAINSHOCK AND RELOCATION OF ITS AFTERSHOCK SEQUENCES

doi:10.3969/j.issn.0253-4967.2016.03.016

Abstract

Abstract:

Using the digital broadband seismic data recorded by Xinjiang network stations, we obtained focal mechanism of the July 3 Pishan, Xinjiang, M_S6.5 earthquake with generalized Cut and Paste(gCAP)inversion method. The strike, dip and rake of first nodal plane are 97°, 27°, 51°, and the second nodal plane are 318°, 70°, 107°. The centroid depth and moment magnitude are calculated to be 12km and 6.4. Combining with the distribution of aftershocks, we conclude that the first nodal plane is the seismogenic fault, and the main shock presents a thrust earthquake at low angle. We relocated 1014 earthquakes using the double-difference algorithm, and finally obtained 937 relocated events. Our results show that the earthquake sequences clearly demonstrate a unilateral extension about 50km nearly in NWW direction, and are mainly located above 25km depth, especially the small earthquakes are predominately located at the shallow parts. Furthermore, the focal depth profile shows a southwestward dipping fault plane at the main shock position, suggesting listric thrust faulting, which is consistent with the dip of the mainshock rupture plane. The spatial distribution of aftershocks represents that the Tarim block was thrust under the West Kunlun orogenic belt. In addition, the dip angle of the fault plane gradually increases along the NWW direction, possibly suggesting a gradual increase of strike-slip component during the NWW rupturing process. From above, we conclude that the Pishan M_S6.5 earthquake is the result of Tibet plateau pushing onto the Tarim block from south to north, which further confirms that the continuous collision of India plate and Eurasia plate has strong influence on the seismic activity in and around the Tibet plateau.

Key words: Pishan M_S6.5 earthquake, focal mechanism, double-difference relocation, thrust fault

摘要：

利用新疆台网记录的波形数据，采用gCAP方法反演得到2015年7月3日新疆皮山M_S6.5地震的最佳双力偶节面解。其中，节面Ⅰ走向97°，倾角27°，滑动角51°；节面Ⅱ走向318°，倾角70°，滑动角107°；最佳矩心深度12km，矩震级M_W6.4；结合余震分布推断此次地震的发震断层为节面Ⅰ，主震破裂表现为逆冲型地震。同时，采用双差定位法对1 014个地震进行相对定位，得到937个重定位地震事件，结果显示余震序列沿NWW向单侧扩展，展布长度约50km；震源深度主要分布在25km之上，且浅部地震较多；深度剖面显示在主震处断层面向SW倾斜，表现为上陡下缓的铲形逆冲断层特征，与主震破裂节面倾角具有较好的一致性。另外，余震序列空间分布展示出塔里木块体向西昆仑造山带下插入，且沿余震扩展的NWW方向，断层面倾角呈现逐渐增大的趋势，可能表明断层在向NWW破裂的过程中走滑分量逐渐增强。此次皮山地震是青藏高原N向挤压塔里木块体的结果，进一步印证了印度板块与欧亚板块的持续碰撞对青藏高原及周边地震活动具有强烈的影响。

关键词: 皮山M_S6.5地震, 震源机制, 双差定位, 逆冲断层

CLC Number:

P315.3

ZHANG Guang-wei, ZHANG Hong-yan, SUN Chang-qing. MECHANISM OF THE 2015 PISHAN, XINJIANG, M_S6.5 MAINSHOCK AND RELOCATION OF ITS AFTERSHOCK SEQUENCES[J]. SEISMOLOGY AND GEOLOGY, 2016, 38(3): 711-720.

张广伟, 张洪艳, 孙长青. 2015年新疆皮山M_S6.5地震震源机制及余震序列定位[J]. 地震地质, 2016, 38(3): 711-720.

References

邓起东, 高翔, 陈桂华, 等. 2010. 青藏高原昆仑-汶川地震系列与巴颜喀喇断块的最新活动［J］. 地学前缘, 17(5):163-178.
DENG Qi-dong, GAO Xiang, CHEN Gui-hua, et al. 2010. Recent tectonic activity of Bayankala fault-block and the Kunlun-Wenchuan earthquake series of the Tibet Plateau［J］. Earth Science Frontiers, 17(5):163-178(in Chinese).
房立华, 吴建平, 王未来, 等. 2013. 四川芦山 M_S7.0 级地震及其余震序列重定位［J］. 科学通报, 58(20):1-9.
FANG Li-hua, WU Jian-ping, WANG Wei-lai, et al. 2013. Relocation of mainshock and aftershock sequences of M_S7.0 Sichuan Lushan earthquake［J］. Chin Sci Bull, 58(20):1-9(in Chinese).
高锐, 黄东定, 卢德源, 等. 2000. 横过西昆仑造山带与塔里木盆地结合带的深地震反射剖面［J］. 科学通报, 45(17):1874-1879.
GAO Rui, HUANG Dong-ding, LU De-yuan, et al. 2000. Deep seismic reflection profile across the junction zone between the Tarim Basin and the West Kunlun Mountains［J］. Chin Sci Bull, 45(17):1874-1879(in Chinese).
高锐, 肖序常, 高弘, 等. 2002. 西昆仑-塔里木-天山岩石圈深地震探测综述［J］. 地质通报, 21(1):11-18.
GAO Rui, XIAO Xu-chang, GAO Hong, et al. 2002. Summary of deep seismic probing of the lithospheric structure across the West Kunlun-Tarim-Tianshan［J］. Geological Bulletin of China, 21(1):11-18(in Chinese).
贺日政, 高锐, 李秋生, 等. 2001. 新疆天山(独山子)-西昆仑(泉水沟)地学断面地震与重力联合反演地壳构造特征［J］. 地球学报, 22(6):553-558.
HE Ri-zheng, GAO Rui, LI Qiu-sheng, et al. 2001. Corridor gravity fields and crustal density structures in Tianshan(Dushanzi)-West Kunlun(Quanshuigou)［J］. Acta Geoscientia Sinica, 22(6):553-558(in Chinese).
李秋生, 卢德源, 高锐, 等. 2000. 横跨西昆仑-塔里木接触带的爆炸地震探测［J］. 中国科学(D辑), 30(S1):16-21.
LI Qiu-sheng, LU De-yuan, GAO Rui, et al. 2000. Explosion seismic probing across the West Kunlun-Tarim contact zone［J］. Science in China(Ser D), 30(S1):16-21(in Chinese).
唐明帅, 葛粲, 郑勇, 等. 2013. 短周期地震仪接收函数的可行性分析:以新疆和田地震台阵为例［J］. 地球物理学报, 56(8):2670-2680.
TANG Ming-shuai, GE Can, ZHENG Yong, et al. 2013. Feasibility analysis of short-period seismograph receiver function-An example of Hotan Seismic Array, Xinjiang［J］. Chinese J Geophys, 56(8):2670-2680(in Chinese).
闻学泽, 杜方, 张培震, 等. 2011. 巴颜喀拉块体北和东边界大地震序列的关联性与2008 年汶川地震［J］. 地球物理学报, 54(3):706-716.
WEN Xu-ze, DU Fang, ZHANG Pei-zhen, et al. 2011. Correlation of major earthquake sequences on the northern and eastern boundaries of the Bayan Har block, and its relation to the 2008 Wenchuan earthquake［J］. Chinese J Geophys, 54(3):706-716(in Chinese).
徐锡伟, 谭锡斌, 吴国栋, 等. 2011. 2008年于田M_S7.3地震地表破裂带特征及其构造属性讨论［J］. 地震地质, 33(2):462-471.
XU Xi-wei, TAN Xi-bin, WU Guo-dong, et al. 2011. Surface rupture features of the 2008 Yutian M_S7.3 earthquake and its tectonic nature［J］. Seismology and Geology, 33(2):462-471(in Chinese).
徐锡伟, 于贵华, 马文涛, 等. 2008. 昆仑山地震(M_W7.8)破裂行为、变形局部化特征及其构造内涵讨论［J］. 中国科学 (D辑), 38(7):785-796.
XU Xi-wei, YU Gui-hua, MA Wen-tao, et al. 2008. Rupture behavior and deformation localization of the Kunlunshan earthquake(M_W7.8)and their tectonic implications［J］. Science in China(Ser D), 51(10):1361-1374.
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. Relocations of Lushan, Sichuan strong earthquake(M_S7.0)and its aftershocks［J］. Chinese J Geophys, 56(5):1674-1771(in Chinese).
张广伟, 雷建设, 梁姗姗, 等. 2014. 2014年8月3日云南鲁甸M_S6.5地震序列重定位与震源机制研究［J］. 地球物理学报, 57(9):3018-3029.
ZHANG Guang-wei, LEI Jian-she. LIANG Shan-shan, et al. 2014. Relocations and focal mechanism solutions of the 3 August 2014 Ludian, Yunnan M_S6.5 earthquake sequence［J］. Chinese J Geophys, 57(9):3018-3029(in Chinese).
张先康, 赵金仁, 张成科, 等. 2002. 帕米尔东北侧地壳结构研究［J］. 地球物理学报, 45(5):665-671.
ZHANG Xian-kang, ZHAO Jin-ren, ZHANG Cheng-ke, et al. 2002. Crustal structure at the northeast side of the Pamirs［J］. Chinese J Geophys, 45(5):665-671(in Chinese).
赵博, 高原, 黄志斌, 等. 2013. 四川芦山M_S7.0地震余震序列双差定位、震源机制及应力场反演［J］. 地球物理学报, 56(10):3385-3395.
ZHAO Bo, GAO Yuan, HUANG Zhi-bin, et al. 2013. Double difference relocation, focal mechanism and stress inversion of Lushan M_S7.0 earthquake sequence［J］. Chinese J Geophysics, 56(10):3385-3395(in Chinese).
郑秀芬, 欧阳飚, 张东宁, 等. 2009. "国家数字测震台网数据备份中心"技术系统建设及其对汶川大地震研究的数据支撑［J］. 地球物理学报, 52(5):1412-1417.
ZHENG Xiu-feng, OUYANG Biao, ZHANG Dong-ning, et al. 2009. Technical system construction of Data Backup Centre for China Seismograph Network and the data support to researchers on the Wenchuan earthquake［J］. Chinese J Geophys, 52(5):1412-1417(in Chinese).
郑勇, 马宏生, 吕坚, 等. 2009. 汶川地震强余震(M_S≥5.6)的震源机制解及其与发震构造的关系［J］. 中国科学 (D辑), 39(4):413-426.
ZHENG Yong, MA Hong-sheng, LV Jian, et al. 2009. Source mechanism of strong aftershocks(M_S≥5.6)of the Wenchuan earthquake and the implication for seismotectonics［J］. Science in China(Ser D), 52(6):739-753.
中国地震局. 2015. 截至7月7日16时00分新疆皮山6.5级地震共记录到余震1298个［EB/OL］. http://www.cea.gov.cn/publish/dizhenj/468/553/101840/101841/20150707162920461670295/index.html.[2015-07-07].
China Earthquake Administration. 2015. 1298 aftershocks were recorded after the Pishan M_S6.5 earthquake till 16:00 of July 7［EB/OL］. http://www.cea.gov.cn/publish/dizhenj/468/553/101840/101841/20150707162920461670295/index.html.[2015-07-07].
中国地震局地质研究所. 2015. 2015年7月3日新疆皮山6.5级地震区域地震构造图［CM/OL］. http://www.eq-igl.ac.cn/upload/images-7/311369477.jpg.[2015-07-03].
Institute of Geology, Chinese Earthquake Adiministration. 2015. Regional seismotectonic map of the July 3, 2015, Pishan, Xinjiang, M_S6.3 earthquake［CM/OL］. http://www.eq-igl.ac.cn/upload/images/2015/7/311369477.jpg.[2015-07-03].
He P, Wang Q, Ding K, et al. 2016. Source model of the 2015 M_W6.4 Pishan earthquake constrained by InSAR and GPS:Insight into blind rupture in the western Kunlun Shan［J］. Geophys Res Lett, 43:1511-1519.
Waldhauser F, Ellsworth W. 2000. A double-difference earthquake location algorithm:Method and application to the Northern Hayward Fault, California［J］. Bull Seismol Soc Am, 90(6):1353-1368.
Wen Y, Xu C, Liu Y, et al. 2016. Deformation and source parameters of the 2015 M_W6.5 earthquake in Pishan, western China, from Sentinel-1A and ALOS-2 data［J］. Remote Sensing, 8(2). doi:10.3390/S8020134.
Zhu L P, Ben-Zion Y. 2013. Parameterization of general seismic potency and moment tensors for source inversion of seismic waveform data［J］. Geophys J Int, 194(2):839-843.
Zhu L P, Helmberger D V. 1996. Advancement in source estimation techniques using broadband regional seismograms［J］. Bull Seism Soc Am, 86(5):1634-1641.
Zhu L P, Rivera L A. 2002. A note on the dynamic and static displacements from a point source in multilayered media［J］. Geophys J Int, 148(3):619-627.

[1]	ZHANG Ling, MIAO Shu-qing, YANG Xiao-ping. THE ANALYSIS AND IMPLEMENTATION OF THE AUTOMATIC EXTRACTING METHOD FOR ACTIVE THRUST FAULTS IN THE NORTH TIANSHAN MOUNTAINS BASED ON ARCGIS SOFTWARE PLATFORM [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(2): 422-434.
[2]	FAN Wen-jie. CHARACTERISTICS OF TECTONIC STRESS FIELD AROUND THE YANGBI M_S6.4 EARTHQUAKE AND ITS SURROUNDING AREAS ON MAY 21, 2021 AND ITS GEODYNAMIC IMPLICATION [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(1): 208-230.
[3]	ZHANG Ke, WANG Xin, YANG Hong-ying, WANG Yue, XU Yan, LI Jing. THE CHARACTERISTICS AND SEISMOGENIC STRUCTURE ANALYSIS OF THE 2021 YANGBI M_S6.4 EARTHQUAKE SEQUENCE, YUNNAN [J]. SEISMOLOGY AND GEOLOGY, 2023, 45(1): 231-251.
[4]	DENG Wen-ze, LIU Jie, YANG Zhi-gao, SUN Li, ZHANG Xue-mei. PRELIMINARY ANALYSIS FOR RUPTURE PROCESS OF THE MAY 22TH, 2021, MADOI(QINGHAI) M_S7.4 EARTHQUAKE [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(4): 1059-1070.
[5]	LI Zong-xu, HE Ri-zheng, JI Zhan-bo, LI Yu-lan, NIU Xiao. THE FOCAL MECHANISM AND TECTONIC SIGNIFICANCE OF THE M_S5.6 EARTHQUAKE ON JULY 24, 2009 IN NIMA, TIBET [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(4): 992-1010.
[6]	WANG Xiao-shan, WAN Yong-ge. CHARACTERISTICS OF THE CRUSTAL STRESS FIELD AND ITS DIRECTION CONVERGENCE BEFORE THE WENCHUAN EARTHQUAKE [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(2): 363-377.
[7]	YU Zhan-yang, SHEN Xu-zhang, LIANG Hao, ZHENG Wen-jun, LIU Xu-zhou. THE CHARACTERISTICS OF MAJOR FAULTS AND STRESS FIELD IN WEIHE-YUNCHENG BASIN CONSTRAINED BY SEISMIC ACTIVITY AND FOCAL MECHANISM SOLUTIONS [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(2): 395-413.
[8]	ZHANG Zhi-wei, LONG Feng, ZHAO Xiao-yan, WANG Di. STUDY ON FOCAL MECHANISM SOLUTION AND STRESS FIELD CHARACTERISTICS IN SICHUAN AND YUNNAN AREA [J]. SEISMOLOGY AND GEOLOGY, 2022, 44(1): 170-187.
[9]	ZHAO Tao, WANG Ying, MA Ji, SHAO Ruo-tong, XU Yi-fei, HU Jing. RELOCATION AND FOCAL MECHANISM SOLUTIONS OF THE 2021 MADUO, QINGHAI M_S7.4 EARTHQUAKE SEQUENCE [J]. SEISMOLOGY AND EGOLOGY, 2021, 43(4): 790-805.
[10]	WANG Ying, ZHAO Tao, HU Jing, LIU Chun. RELOCATION AND FOCAL MECHANISM SOLUTIONS OF THE 2021 YANGBI, YUNNAN M_S6.4 EARTHQUAKE SEQUENCE [J]. SEISMOLOGY AND EGOLOGY, 2021, 43(4): 847-863.
[11]	CUI Ren-sheng, ZHAO Cui-ping, ZHOU Lian-qing, CHEN Yang. SEISMICITY FEATURE AND SEISMOGENIC FAULT OF THE M_S6.4 EARTHQUAKE SEQUENCE ON JANUARY 19, 2020 IN JIASHI, XINJIANG [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(2): 329-344.
[12]	GUO Zhi, GAO Xing, LU Zhen. RELOCATION AND FOCAL MECHANISM FOR THE XINJIANG JIASHI EARTHQUAKE ON 19 JANUARY, 2020 [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(2): 345-356.
[13]	LI Jin, JIANG Hai-kun, WEI Yun-yun, SUN Zhao-jie. PRELIMINARY STUDY FOR SEISMOGENIC STRUCTURE OF THE M_S6.4 JIASHI EARTHQUAKE ON JANUARY 19, 2020 [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(2): 357-376.
[14]	ZHANG Wen-ting, JI Ling-yun, ZHU Liang-yu, JIANG Feng-yun, XU Xiao-xue. A TYPICAL THRUST RUPTURE EVENT OCCURRING IN THE FORELAND BASIN OF THE SOUTHERN TIANSHAN: THE 2020 XINJIANG JIASHI M_S6.4 EARTHQUAKE [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(2): 394-409.
[15]	LIU Xu-zhou, SHEN Xu-zhang, HE Xiao-hui, PU Ju. RELOCATION OF THE 28 OCTOBER 2019 XIAHE M5.7 EARTHQUAKE SEQUENCE AND ANALYSIS OF SEISMOGENIC FAULT [J]. SEISMOLOGY AND GEOLOGY, 2021, 43(1): 197-208.