冷龙岭地区2016年青海门源6.4级地震发震构造特征
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摘要
青海门源北部的冷龙岭断裂带于2016年发生M_S6.4地震,该地震与1986年发生的另一次M_S6.4地震的震源机制解截然不同,并且二者与冷龙岭主断层几乎表现为纯左旋走滑的性质也差异很大。为明确2次地震的发震构造特征,分析二者与冷龙岭主断层的关系,利用Sentinel-1A数据干涉处理得到了2016年地震的同震形变场,并结合高分辨率影像、余震精定位及GPS资料对断层构造样式及地震构造特征进行了研究。研究结果表明,2016年地震发生在冷龙岭断裂带西段北侧的分支断层上,地震造成分支断层两侧发生背斜式褶曲隆升。2次地震分别发生在分支断层的东西两端,其两端分别向冷龙岭主断层弯曲收敛并交会,在平面上形成左行右阶与左行左阶的几何结构,在区域整体剪切环境下,分别发生剪切挤压与剪切拉张,因而造成2次地震的震源机制解分别表现为压性与张性为主又兼具一定的走滑性质,综合认为分支断层与主断层之间的构造组合样式是导致2个不同震源机制解的主要因素。2次地震活动皆反映了冷龙岭断裂带整体表现为左旋走滑运动特征,该构造变形机制也体现了祁连-海原构造带对青藏高原东北缘的构造调节作用,即来自于青藏板块的构造运动在受到北部戈壁-阿拉善块体及东部华北克拉通块体的阻挡后,在青藏高原东北缘通过一系列左旋走滑断裂的调节,构造运动方向逐渐发生顺时针旋转。门源地震使得对冷龙岭断裂带地震地质问题的深入研究更加紧迫。
On January 21 2016,an earthquake of M_S6. 4 hit the Lenglongling fault zone(LLLFZ) in the NE Tibetan plateau,which has a contrary focal mechanism solution to the Ms 6. 4 earthquake occurring in1986. Fault behaviors of both earthquakes in 1986 and 2016 are also quite different from the left-lateral strike-slip pattern of the Lenglongling fault zone. In order to find out the seismogenic structure of both earthquakes and figure out relationships among the two earthquakes and the LLLFZ,In SAR co-seismic deformation map is constructed by Sentinel-1A data. Moreover,the geological map,remote sensing images,relocation of aftershocks and GPS data are also combined in the research. The In SAR results indicate that the co-seismic deformation fields are distributed on both sides of the branch fault(F2) on the northwest of the Lenglongling main fault(F1),where the Earth's surface uplifts like a tent during the 2016 earthquake. The 2016 and 1986 earthquakes occurred on the eastern and western bending segments of the F2 respectively,where the two parts of the F2 bend gradually and finally join with the F1. The intersections between the F1 and F2compose the right-order and left-order alignments in the planar geometry,which lead to the restraining bend and releasing bend because of the left-lateral strike-slip movement,respectively. Therefore,the thrust and normal faults are formed in the two bending positions. In consequence,the focal mechanism solutions of the2016 and 1986 earthquakes mainly present the compression and tensional behaviors,respectively,both of which also behave as slight strike-slip motion. All results indicate that seismic activity and tectonic deformation of the LLLFZ play important parts in the Qilian-Haiyuan tectonic zone,as well as in the NE Tibetan plateau. The complicated tectonic deformation of NE Tibetan plateau results from the collisions from three different directions between the north Eurasian plate,the east Pacific plate and the southwest Indian plate. The intensive tectonic movement leads to a series of left-lateral strikeslip faults in this region and the tectonic deformation direction rotates clockwise gradually to the east along the Qilian-Haiyuan tectonic zone. The Menyuan earthquake makes it very important to reevaluate the earthquake risk of this region.
On January 21 2016,an earthquake of M_S6. 4 hit the Lenglongling fault zone(LLLFZ) in the NE Tibetan plateau,which has a contrary focal mechanism solution to the Ms 6. 4 earthquake occurring in1986. Fault behaviors of both earthquakes in 1986 and 2016 are also quite different from the left-lateral strike-slip pattern of the Lenglongling fault zone. In order to find out the seismogenic structure of both earthquakes and figure out relationships among the two earthquakes and the LLLFZ,In SAR co-seismic deformation map is constructed by Sentinel-1A data. Moreover,the geological map,remote sensing images,relocation of aftershocks and GPS data are also combined in the research. The In SAR results indicate that the co-seismic deformation fields are distributed on both sides of the branch fault(F2) on the northwest of the Lenglongling main fault(F1),where the Earth's surface uplifts like a tent during the 2016 earthquake. The 2016 and 1986 earthquakes occurred on the eastern and western bending segments of the F2 respectively,where the two parts of the F2 bend gradually and finally join with the F1. The intersections between the F1 and F2compose the right-order and left-order alignments in the planar geometry,which lead to the restraining bend and releasing bend because of the left-lateral strike-slip movement,respectively. Therefore,the thrust and normal faults are formed in the two bending positions. In consequence,the focal mechanism solutions of the2016 and 1986 earthquakes mainly present the compression and tensional behaviors,respectively,both of which also behave as slight strike-slip motion. All results indicate that seismic activity and tectonic deformation of the LLLFZ play important parts in the Qilian-Haiyuan tectonic zone,as well as in the NE Tibetan plateau. The complicated tectonic deformation of NE Tibetan plateau results from the collisions from three different directions between the north Eurasian plate,the east Pacific plate and the southwest Indian plate. The intensive tectonic movement leads to a series of left-lateral strikeslip faults in this region and the tectonic deformation direction rotates clockwise gradually to the east along the Qilian-Haiyuan tectonic zone. The Menyuan earthquake makes it very important to reevaluate the earthquake risk of this region.
引文
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李永生,冯万鹏,张景发,等.2015.2014年美国加州纳帕MW6.1地震断层参数的Sentinel-1A InS AR反演[J].地球物理学报,58(7):2339-2349.doi:10.6038/cjg20150712.LI Yong-sheng,FENG Wan-peng,ZHANG Jing-fa,et al.2015.Coseismic slip of the 2014 MW6.1 Napa,California earthquake revealed by Sentinel-1A InS AR[J].Chinese Journal of Geophysics,58(7):2339-2349(in Chinese).
李永生,申文豪,温扬茂,等.2016.2015年尼泊尔MW7.8地震震源机制InS AR反演及强地面运动模拟[J].地球物理学报,59(4):1359-1370.doi:10.6038/cjg20160417.LI Yong-sheng,SHEN Wen-hao,WEN Yang-mao,et al.2016.Source parameters for the 2015 Nepal earthquake revealed by InS AR observations and strong ground motion simulation[J].Chinese Journal of Geophysics,59(4):1359-1370(in Chinese).
屈春燕,单新建,张国宏,等.2014.时序InS AR断层活动性观测研究进展及若干问题探讨[J].地震地质,36(3):731-748.doi:10.3969/j.issn.0253-4967.2014.03.015.QU Chun-yan,SHAN Xin-jian,ZHANG Guo-hong,et al.2014.The research progress in measurement of fault activity by time series InS AR and discussion of related issues[J].Seismology and Geology,36(3):731-748(in Chinese).
单新建,屈春燕,宋小刚,等.2009.汶川MS8.0地震InS AR同震形变场观测与研究[J].地球物理学报,52(2):496-504.SHAN Xin-jian,QU Chun-yan,SONG Xiao-gang,et al.2009.Coseismic surface deformation caused by the Wenchuan MS8.0 earthquake from InS AR data analysis[J].Chinese Journal of Geophysics,52(2):496-504(in Chinese).
单新建,张国宏,汪驰升,等.2015.基于InS AR和GPS观测数据的尼泊尔地震发震断层特征参数联合反演研究[J].地球物理学报,58(11):4266-4276.doi:10.6038/cjg20151131.SHAN Xin-jian,ZHANG Guo-hong,WANG Chi-sheng,et al.2015.Joint inversion for the spatial fault slip distribution of the 2015 Nepal MW7.9 earthquake based on InS AR and GPS observations[J].Chinese Journal of Geophysics,58(11):4266-4276(in Chinese).
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徐纪人,姚立珣,汪进.1986.1986年8月26日门源6.4级地震及其强余震的震源机制解[J].西北地震学报,8(4):82-84.XU Ji-ren,YAO Li-xun,WANG Jin.1986.Earthquake source mechanisms of Menyuan earthquake(MS=6.4,on Aug.26,1986)and its strong aftershocks[J].Northwestern Seismological Journal,8(4):82-84(in Chinese).
袁道阳,刘百篪,吕太乙,等.1998.北祁连山东段活动断裂带的分段性研究[J].西北地震学报,20(4):27-34.YUAN Dao-yang,LIU Bai-chi,LTai-yi,et al.1998.Study on the segmentation in east segment of the northern Qilian fault zone[J].Northwestern Seismological Journal,20(4):27-34(in Chinese).
袁道阳,张培震,刘百篪,等.2004.青藏高原东北缘晚第四纪活动构造的几何图像与构造转换[J].地质学报,78(2):270-278.YUAN Dao-yang,ZHANG Pei-zhen,LIU Bai-chi,et al.2004.Geometrical imagery and tectonic transformation of late Quaternary active tectonics in northeastern margin of Qinghai-Xizang plateau[J].Acta Geologica Sinica,78(2):270-278(in Chinese).
赵文津,Mechie J,冯梅,等.2014.祁连山造山作用与岩石圈地幔的特型结构构造[J].中国地质,41(5):1411-1423.ZHAO Wen-jin,Mechie J,FENG Mei,et al.2014.Cenozoic orogenesis of the Qilian Mountain and the lithosphere mantle tectonic framework beneath it[J].Geology in China,41(5):1411-1423(in Chinese).
郑文俊,袁道阳,何文贵.2004.祁连山东段天桥沟-黄羊川断裂古地震活动习性研究[J].地震地质,26(4):645-657.doi:10.3969/j.issn.0253-4967.2004.04.011.ZHENG Wen-jun,YUAN Dao-yang,HE Wen-gui.2004.Characteristics of palaeo-earthquake activity along the active Tianqiaogou-Huangyangchuan Fault on the eastern section of the Qilianshan Mountains[J].Seismology and Geology,26(4):645-657(in Chinese).
Gaudemer Y,Tapponnier P,Meyer B,et al.1995.Partitioning of crustal slip between linked,active faults in the eastern Qilian Shan,and evidence for a major seismic gap,the‘Tianzhu gap’,on the western Haiyuan Fault,Gansu(China)[J].Geophysical Journal International,120(3):599-645.
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Jing L Z,Klinger Y,Xu X W,et al.2007.Millennial recurrence of large earthquakes on the Haiyuan Fault near Songshan,Gansu Province,China[J].Bulletin of the Seismological Society of America,97(1B):14-34.doi.10.1785/0120050118.
Lasserre C,Gaudemer Y,Tapponnier P,et al.2002.Fast late Pleistocene slip rate on the Leng Long Ling segment of the Haiyuan Fault,Qinghai,China[J].Journal of Geophysical Research,107(B11):2276.doi:10.1029/2000JB000060.
Li Y S,Jiang W L,Zhang J F,et al.2016.Space geodetic observations and modeling of 2016 MW5.9 Menyuan earthquake:Implications on seismogenic tectonic motion[J].Remote Sensing,8(6):519.doi:10.3390/rs8060519.
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房立华,吴建平,王未来,等.2013.四川芦山MS7.0地震及其余震序列重定位[J].科学通报,58(20):1901-1909.FANG Li-hua,WU Jian-ping,WANG Wei-lai,et al.2013.Relocation of the mainshock and aftershock sequences of MS7.0 Sichuan Lushan earthquake[J].China Science Bulletin,58(28):3451-3459.
房立华,吴建平,王未来,等.2015.2014年新疆于田MS7.3地震序列重定位[J].地球物理学报,58(3):802-808.FANG Li-hua,WU Jian-ping,WANG Wei-lai,et al.2015.Relocation of the 2014 MS7.3 earthquake sequence inYutian,Xinjiang[J].Chinese Journal of Geophysics,58(3):802-808(in Chinese).
何文贵,刘百篪,袁道阳,等.2000.冷龙岭活动断裂的滑动速率研究[J].西北地震学报,22(1):90-97.HE Wen-gui,LIU Bai-chi,YUAN Dao-yang,et al.2000.Research on slip rates of the Lenglongling active fault zone[J].Northwestern Seismological Journal,22(1):90-97(in Chinese).
何文贵,刘百篪,袁道阳.2001.冷龙岭断裂古地震初步研究[M]∥汪一鹏.活动断裂研究(8):理论与应用.北京:地震出版社:64-74.HE Wen-gui,LIU Bai-chi,YUAN Dao-yang.2001.Preliminary study of the paleoearthquake on Lenglongling Fault[M]∥WANG Yi-peng(ed).Research on Active Fault(8):Theory and Application.Seismological Press,Beijing:64-74(in Chinese).
何文贵,袁道阳,葛伟鹏,等.2010.祁连山活动断裂带中东段冷龙岭断裂滑动速率的精确厘定[J].地震,30(1):131-137.HE Wen-gui,YUAN Dao-yang,GE Wei-peng,et al.2010.Determination of the slip rate of the Lenglongling Fault in the middle and eastern segments of the Qilian mountain active fault zone[J].Earthquake,30(1):131-137(in Chinese).
李永生,冯万鹏,张景发,等.2015.2014年美国加州纳帕MW6.1地震断层参数的Sentinel-1A InS AR反演[J].地球物理学报,58(7):2339-2349.doi:10.6038/cjg20150712.LI Yong-sheng,FENG Wan-peng,ZHANG Jing-fa,et al.2015.Coseismic slip of the 2014 MW6.1 Napa,California earthquake revealed by Sentinel-1A InS AR[J].Chinese Journal of Geophysics,58(7):2339-2349(in Chinese).
李永生,申文豪,温扬茂,等.2016.2015年尼泊尔MW7.8地震震源机制InS AR反演及强地面运动模拟[J].地球物理学报,59(4):1359-1370.doi:10.6038/cjg20160417.LI Yong-sheng,SHEN Wen-hao,WEN Yang-mao,et al.2016.Source parameters for the 2015 Nepal earthquake revealed by InS AR observations and strong ground motion simulation[J].Chinese Journal of Geophysics,59(4):1359-1370(in Chinese).
屈春燕,单新建,张国宏,等.2014.时序InS AR断层活动性观测研究进展及若干问题探讨[J].地震地质,36(3):731-748.doi:10.3969/j.issn.0253-4967.2014.03.015.QU Chun-yan,SHAN Xin-jian,ZHANG Guo-hong,et al.2014.The research progress in measurement of fault activity by time series InS AR and discussion of related issues[J].Seismology and Geology,36(3):731-748(in Chinese).
单新建,屈春燕,宋小刚,等.2009.汶川MS8.0地震InS AR同震形变场观测与研究[J].地球物理学报,52(2):496-504.SHAN Xin-jian,QU Chun-yan,SONG Xiao-gang,et al.2009.Coseismic surface deformation caused by the Wenchuan MS8.0 earthquake from InS AR data analysis[J].Chinese Journal of Geophysics,52(2):496-504(in Chinese).
单新建,张国宏,汪驰升,等.2015.基于InS AR和GPS观测数据的尼泊尔地震发震断层特征参数联合反演研究[J].地球物理学报,58(11):4266-4276.doi:10.6038/cjg20151131.SHAN Xin-jian,ZHANG Guo-hong,WANG Chi-sheng,et al.2015.Joint inversion for the spatial fault slip distribution of the 2015 Nepal MW7.9 earthquake based on InS AR and GPS observations[J].Chinese Journal of Geophysics,58(11):4266-4276(in Chinese).
汪进,秦保燕,董奇珍.1992.1986年8月26日门源6.4级地震破裂过程研究[J].华北地震科学,10(2):25-33.WANG Jin,QIN Bao-yan,DONG Qi-zhen.1992.A study on the fracture process of the Menyuan M6.4 earthquake occurred on August 26,1986[J].North China Earthquake Sciences,10(2):25-33(in Chinese).
徐纪人,姚立珣,汪进.1986.1986年8月26日门源6.4级地震及其强余震的震源机制解[J].西北地震学报,8(4):82-84.XU Ji-ren,YAO Li-xun,WANG Jin.1986.Earthquake source mechanisms of Menyuan earthquake(MS=6.4,on Aug.26,1986)and its strong aftershocks[J].Northwestern Seismological Journal,8(4):82-84(in Chinese).
袁道阳,刘百篪,吕太乙,等.1998.北祁连山东段活动断裂带的分段性研究[J].西北地震学报,20(4):27-34.YUAN Dao-yang,LIU Bai-chi,LTai-yi,et al.1998.Study on the segmentation in east segment of the northern Qilian fault zone[J].Northwestern Seismological Journal,20(4):27-34(in Chinese).
袁道阳,张培震,刘百篪,等.2004.青藏高原东北缘晚第四纪活动构造的几何图像与构造转换[J].地质学报,78(2):270-278.YUAN Dao-yang,ZHANG Pei-zhen,LIU Bai-chi,et al.2004.Geometrical imagery and tectonic transformation of late Quaternary active tectonics in northeastern margin of Qinghai-Xizang plateau[J].Acta Geologica Sinica,78(2):270-278(in Chinese).
赵文津,Mechie J,冯梅,等.2014.祁连山造山作用与岩石圈地幔的特型结构构造[J].中国地质,41(5):1411-1423.ZHAO Wen-jin,Mechie J,FENG Mei,et al.2014.Cenozoic orogenesis of the Qilian Mountain and the lithosphere mantle tectonic framework beneath it[J].Geology in China,41(5):1411-1423(in Chinese).
郑文俊,袁道阳,何文贵.2004.祁连山东段天桥沟-黄羊川断裂古地震活动习性研究[J].地震地质,26(4):645-657.doi:10.3969/j.issn.0253-4967.2004.04.011.ZHENG Wen-jun,YUAN Dao-yang,HE Wen-gui.2004.Characteristics of palaeo-earthquake activity along the active Tianqiaogou-Huangyangchuan Fault on the eastern section of the Qilianshan Mountains[J].Seismology and Geology,26(4):645-657(in Chinese).
Gaudemer Y,Tapponnier P,Meyer B,et al.1995.Partitioning of crustal slip between linked,active faults in the eastern Qilian Shan,and evidence for a major seismic gap,the‘Tianzhu gap’,on the western Haiyuan Fault,Gansu(China)[J].Geophysical Journal International,120(3):599-645.
Hetzel R,Niedermann S,Tao M X,et al.2002.Low slip rates and long-term preservation of geomorphic features in Central Asia[J].Nature,417:428-432.
Jing L Z,Klinger Y,Xu X W,et al.2007.Millennial recurrence of large earthquakes on the Haiyuan Fault near Songshan,Gansu Province,China[J].Bulletin of the Seismological Society of America,97(1B):14-34.doi.10.1785/0120050118.
Lasserre C,Gaudemer Y,Tapponnier P,et al.2002.Fast late Pleistocene slip rate on the Leng Long Ling segment of the Haiyuan Fault,Qinghai,China[J].Journal of Geophysical Research,107(B11):2276.doi:10.1029/2000JB000060.
Li Y S,Jiang W L,Zhang J F,et al.2016.Space geodetic observations and modeling of 2016 MW5.9 Menyuan earthquake:Implications on seismogenic tectonic motion[J].Remote Sensing,8(6):519.doi:10.3390/rs8060519.
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