龙门山断裂带晚第四纪的大地震活动——来自古地震研究的资料
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摘要
2018年5·12汶川地震后,龙门山断裂带的大地震活动特征一直是倍受关注的科学问题.而探槽古地震研究是最直接揭示活断层带晚第四纪大地震活动规律的重要途径.本文通过系统总结龙门山断裂带近十年来探槽古地震研究成果,全面分析了龙门山断裂带不同段落的晚第四纪大地震活动与复发特征.结果显示:龙门山断裂带的大地震活动具有明显的分段性,北川—映秀断裂和江油—灌县断裂中段(包括小鱼洞断裂)是全新世以来,最为活跃的段落,约距今6000年以来,发生过3次位移量近似相等的事件,分别发生在5920—5730cal BP和3300—2300cal BP,大地震活动具有3000年左右的准周期复发特征;北川—映秀断裂的北段具有独立破裂的能力,该段汶川地震前一次事件发生在大约665—1030AD,可能是历史上记载的942AD地震事件,另一次事件发生在8240—7785BC;江油—灌县断裂的南段(大川—双石断裂)发震能力明显弱于断裂带中段和北段.现有古地震数据表明,沿北川—映秀断裂,除汶川地震以外,并未显示出不同段落间在全新世期间存在级联破裂的证据,这可能意味着2008年汶川M8地震是龙门山断裂带上罕见的巨大地震事件.另外,青川断裂上探槽揭露的古地震变形事件不像是断裂直接位错的结果,更可能是被动响应北川—映秀断裂右旋位错的现象.
The fault activity of the Longmen Shan fault zone has been focused since the Wenchuan earthquake occurred on May 12,2018.Paleoseismic trenching has been suggested to be the mosteffective way to reveal Late-Quaternary fault rupture behavior.This paper integrates about 10-year paleoseismic studies on the Longmen Shan fault to further reveal its Late-Quaternary rupture behavior and recurrence characteristics.Herein we suggest that rupture behavior of the Longmen Shan fault shows segmentation characteristics.Fault activity of the middle segment of the Yingxiu-Beichuan and Jiangyou-Guanxian fault(including the Xiaoyudong fault)has been the most intense part since Holocene.Specifically,the segment ruptured three times since about 6000 years with a similar coseismic offset,the penultimate and third oldest event occurred at 3300—2300 cal BP and 5920—5730 cal BP,which indicates an average recurrence interval of about 3000 years.The northern segment of the Yingxiu-Beichuan fault had independent rupture behavior,the penultimate event on the segment ruptured at about 665—1030 AD that is associated with historical record 942 AD earthquake.The third oldest event occurred at 8240—7785 BC.The southern segment of the Jiangyou-Guanxian fault(Dachuan-Shaungshi fault)shows a weaker seismic potential than that of the middle and northern segments.The present paleoseismic data except for the 2018 Wenchuan earthquake that are associated with the Yingxiu-Beichuan fault suggest that no evidence has supported a cascading rupture behavior of the Yingxiu-Beichuan fault,which indicates that the 2018 Wenchuan earthquake might be an unusual great seismic event.Moreover,deformation evidence revealed from trenching on the Qingchuan fault might not be related to fault offset,but more possibly be related to responding deformation due to coseismic right-laterally offset of the Yingxiu-Beichuan fault.
The fault activity of the Longmen Shan fault zone has been focused since the Wenchuan earthquake occurred on May 12,2018.Paleoseismic trenching has been suggested to be the mosteffective way to reveal Late-Quaternary fault rupture behavior.This paper integrates about 10-year paleoseismic studies on the Longmen Shan fault to further reveal its Late-Quaternary rupture behavior and recurrence characteristics.Herein we suggest that rupture behavior of the Longmen Shan fault shows segmentation characteristics.Fault activity of the middle segment of the Yingxiu-Beichuan and Jiangyou-Guanxian fault(including the Xiaoyudong fault)has been the most intense part since Holocene.Specifically,the segment ruptured three times since about 6000 years with a similar coseismic offset,the penultimate and third oldest event occurred at 3300—2300 cal BP and 5920—5730 cal BP,which indicates an average recurrence interval of about 3000 years.The northern segment of the Yingxiu-Beichuan fault had independent rupture behavior,the penultimate event on the segment ruptured at about 665—1030 AD that is associated with historical record 942 AD earthquake.The third oldest event occurred at 8240—7785 BC.The southern segment of the Jiangyou-Guanxian fault(Dachuan-Shaungshi fault)shows a weaker seismic potential than that of the middle and northern segments.The present paleoseismic data except for the 2018 Wenchuan earthquake that are associated with the Yingxiu-Beichuan fault suggest that no evidence has supported a cascading rupture behavior of the Yingxiu-Beichuan fault,which indicates that the 2018 Wenchuan earthquake might be an unusual great seismic event.Moreover,deformation evidence revealed from trenching on the Qingchuan fault might not be related to fault offset,but more possibly be related to responding deformation due to coseismic right-laterally offset of the Yingxiu-Beichuan fault.
引文
Burchfiel B C,Royden L H,Van Der Hilst R D,et al.2008.Ageological and geophysical context for the Wenchuan earthquake of 12May 2008,Sichuan,People′s Republic of China.GSA Today,18(7):4-11.
Chen G G,Ji F J,Zhou R J,et al.2007.Primary research of activity segmentation of Longmenshan fault zone since late-Quaternary.Seismology and Geology(in Chinese),29(3):657-673.
Chen J.2013.New development in the study of Pre-Qin seismological archaeology and its inspiration to prehistoric seismological archaeology in the Longmen Mountain Area.Journal of Ethnology(in Chinese),4(4):35-53.
Chen L C,Ran Y K,Chen J,et al.2009.Geological and geomorphic evidence for repeatedly occurring severe earthquakes on fronter-range fault of Longmenshan,China.Quaternary Sciences(in Chinese),29(3):472-483.
Chen L C,Ran Y K,Wang H,et al.2013.Paleoseismology and kinematic characteristics of the Xiaoyudong rupture,a short but significant strange segment characterized by the May 12,2008,MW7.9earthquake in Sichuan,China.Tectonophysics,584:91-101.
Chen L C,Ran Y K,Wang H,et al.2013.The Lushan MS7.0earthquake and activity of the southern segment of the Longmenshan fault zone.Chinese Science Bulletin,58(S2):3475-3482.
Chen S F,Wilson C J L,Deng Q D,et al.1994.Active faulting and block movement associated with large earthquakes in the Min Shan and Longmen Mountains,northeastern Tibetan Plateau.Journalof Geophysical Research:Solid Earth,99(B12):24205-24038.
Deng Q D,Chen S F,Zhao X L,1994.Tectonics,seismicity and dynamics of Longmenshan Mountains and its adjacent regions.Seismology and Geology(in Chinese),16(4):389-403.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26(4):TC4005,doi:10.1029/2006TC001987.
Kirby E,Reiners P W,Krol M A,et al.2002.Late Cenozoic evolution of the eastern margin of the Tibetan Plateau:Inferences from40 Ar/39 Ar and(U-Th)/He thermochronology.Tectonics,21(1):1001,doi:10.1029/2000TC001246.
Li C Y,Song F M,Ran Y K.2004.Late quaternary activity and age constraint of the northern Longmenshan fault zone.Seismology and Geology(in Chinese),26(2):248-258.
Li H B,Wang H,Xu Z Q,et al.2013.Characteristics of the faultrelated rocks,fault zones and the principal slip zone in the Wenchuan Earthquake Fault Scientific Drilling Project Hole-1(WFSD-1).Tectonophysics,584:23-42.
Li Y,Allen P A,Zhou R J,et al.2006.Mesozoic-Cenozoic dynamics of Longmenshan foreland basin along the eastern margin of the Tibetan Plateau and its coupled relationship with continent collision.Acta Geologica Sinica(in Chinese),80(8):1101-1109.
Li Z W,Liu S G,Chen H D,et al.2008.Structural segmentation and zonation and differential deformation across and along the Longmen thrust belt,West Sichuan,China.Journal of Chengdu University of Technology(Science&Technology Edition)(in Chinese),35(4):440-455.
Lin A M,Rao G,Yan B.2012.Field evidence of rupture of the Qingchuan Fault during the 2008 MW7.9 Wenchuan earthquake,northeastern segment of the Longmen Shan Thrust Belt,China.Tectonophysics,522-523:243-252.
Liu M,Luo G,Wang H.2014.The 2013 Lushan earthquake in China tests hazard assessment.Seismological Research Letters,85(1):40-43,doi:10.1785/0220130117.
Ma B Q,Su G,Hou Z H,et al.2005.Late Quaternary slip rate in the central part of the Longmenshan fault zone from terrace deformation along the Minjiang River.Seismology and Geology(in Chinese),27(2):234-242.
Meade B J.2007.Present-day kinematics at the India-Asia collision zone.Geology,35(1):81-84.
Pan J W,Li H B,Si J L,et al.2014.Rupture process of the Wenchuan earthquake(MW7.9)from surface ruptures and fault striations characteristics.Tectonophysics,619-620:13-28.
Ran Y K,Chen L C,Chen J,et al.2010.Paleoseismic evidence and repeat time of large earthquakes at three sites along the Longmenshan fault zone.Tectonophysics,491(1-4):141-153.
Ran Y K,Chen L C,Chen W S,et al.2012.Key techniques and several cases analysis in paleoseismic studies in mainland China(2):Surface deformation characteristics of Wenchuan earthquake and paleoseismic indicators on fold-reverse fault.Seismology and Geology(in Chinese),33(3):386-400.
Ran Y K,Chen W S,Xu X W,et al.2013.Paleoseismic events and recurrence interval along the Beichuan-Yingxiu fault of Longmenshan fault zone,Yingxiu,Sichuan,China.Tectonophysics,584:81-90.
Ran Y K,Chen W S,Xu X W,et al.2014.Late Quaternary paleoseismic behavior and rupture segmentation of the YingxiuBeichuan fault along the Longmen Shan fault zone,China.Tectonics,33(11):2218-2232,doi:10.1002/2014tc003649.
Shen Z K,Lu J M,Wang M,et al.2005.Contemporary crustal deformation around the southeast borderland of the Tibetan Plateau.Journal of Geophysical Research:Solid Earth,110(B11):B11409,doi:10.1029/2004JB003421.
Shen Z K,Sun J Z,Zhang P Z,et al.2009.Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake.Nature Geoscience,2(10):718-724.
Shi X,Ran Y K,Chen L C,et al.2009.Preliminary study on paleoearthquake at Beichuan-Dengjia segment along the central fault of Longmen Mountain.Quaternary Sciences(in Chinese),29(3):494-501.
Sun H Y,He H L,Ikeda Y,et al.2015.Holocene paleoearthquake history on the Qingchuan fault in the northeastern segment of the Longmenshan Thrust Zone and its implications.Tectonophysics,660:92-106.
Wang H,Chen L C,Ran Y K,et al.2015.Paleoseismic investigation of the seismic gap between the seismogenic structures of the 2008Wenchuan and 2013Lushan earthquakes along the Longmen Shan fault zone at the eastern margin of the Tibetan Plateau.Lithosphere,7(1):14-20.
Zhang P Z,Xu X W,Wen X Z,et al.2008.Slip rates sand recurrence intervals of the Longmenshan active fault zone,and tectonic implications for the mechanism of the May 12 Wenchuan earthquake,2008,Sichuan,China.Chinese Journal of Geophysics(in Chinese),51(4):1066-1073.
Zhu S B,Zhang P Z.2013.FEM simulation of interseismic and coseismic deformation associated with the 2008 Wenchuan earthquake.Tectonophysics,584:64-80.
陈国光,计凤桔,周荣军等.2007.龙门山断裂带晚第四纪活动性分段的初步研究.地震地质,26(3):657-673.
陈剑.2013.先秦地震考古研究的新进展及其对龙门山地区史前地震考古的启示.民族学刊,4(4):35-53.
陈立春,冉勇康,陈杰等.2009.龙门山前山断裂大地震原地重复发生的地质地貌证据.第四纪研究.29(3):472-483.
陈立春,冉勇康,王虎等.2013.芦山地震与龙门山断裂带南段活动性.科学通报,58(20):1925-1932.
邓起东,陈社发,赵小麟.1994.龙门山及其邻区的构造和地震活动及动力学.地震地质,16(4):389-403.
李传友,宋方敏,冉勇康.2004.龙门山断裂带北段晚第四纪活动性讨论.地震地质,26(2):248-258.
李勇,Allen P A,周荣军等.2006.青藏高原东缘中新生代龙门山前陆盆地动力学及其与大陆碰撞作用的耦合关系.地质学报,80(8):1101-1109.
李智武,刘树根,陈洪德等.2008.龙门山冲断带分段-分带性构造格局及其差异变形特征.成都理工大学学报,35(4):440-454.
马保起,苏刚,侯治华等.2005.利用岷江阶地的变形估算龙门山断裂带中段晚第四纪滑动速率.地震地质,27(2):234-242.
冉勇康,陈立春,陈文山等.2012.中国大陆古地震研究的关键技术与案例解析(2)---汶川地震地表变形特征与褶皱逆断层古地震识别.地震地质,33(3):386-400.
史翔,冉勇康,陈立春等.2009.龙门山中央断裂北川-邓家一带古地震初步研究.第四纪研究,29(3):494-501.
张培震,徐锡伟,闻学泽等.2008.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因.地球物理学报,51(4):1066-1073.
Chen G G,Ji F J,Zhou R J,et al.2007.Primary research of activity segmentation of Longmenshan fault zone since late-Quaternary.Seismology and Geology(in Chinese),29(3):657-673.
Chen J.2013.New development in the study of Pre-Qin seismological archaeology and its inspiration to prehistoric seismological archaeology in the Longmen Mountain Area.Journal of Ethnology(in Chinese),4(4):35-53.
Chen L C,Ran Y K,Chen J,et al.2009.Geological and geomorphic evidence for repeatedly occurring severe earthquakes on fronter-range fault of Longmenshan,China.Quaternary Sciences(in Chinese),29(3):472-483.
Chen L C,Ran Y K,Wang H,et al.2013.Paleoseismology and kinematic characteristics of the Xiaoyudong rupture,a short but significant strange segment characterized by the May 12,2008,MW7.9earthquake in Sichuan,China.Tectonophysics,584:91-101.
Chen L C,Ran Y K,Wang H,et al.2013.The Lushan MS7.0earthquake and activity of the southern segment of the Longmenshan fault zone.Chinese Science Bulletin,58(S2):3475-3482.
Chen S F,Wilson C J L,Deng Q D,et al.1994.Active faulting and block movement associated with large earthquakes in the Min Shan and Longmen Mountains,northeastern Tibetan Plateau.Journalof Geophysical Research:Solid Earth,99(B12):24205-24038.
Deng Q D,Chen S F,Zhao X L,1994.Tectonics,seismicity and dynamics of Longmenshan Mountains and its adjacent regions.Seismology and Geology(in Chinese),16(4):389-403.
Densmore A L,Ellis M A,Li Y,et al.2007.Active tectonics of the Beichuan and Pengguan faults at the eastern margin of the Tibetan Plateau.Tectonics,26(4):TC4005,doi:10.1029/2006TC001987.
Kirby E,Reiners P W,Krol M A,et al.2002.Late Cenozoic evolution of the eastern margin of the Tibetan Plateau:Inferences from40 Ar/39 Ar and(U-Th)/He thermochronology.Tectonics,21(1):1001,doi:10.1029/2000TC001246.
Li C Y,Song F M,Ran Y K.2004.Late quaternary activity and age constraint of the northern Longmenshan fault zone.Seismology and Geology(in Chinese),26(2):248-258.
Li H B,Wang H,Xu Z Q,et al.2013.Characteristics of the faultrelated rocks,fault zones and the principal slip zone in the Wenchuan Earthquake Fault Scientific Drilling Project Hole-1(WFSD-1).Tectonophysics,584:23-42.
Li Y,Allen P A,Zhou R J,et al.2006.Mesozoic-Cenozoic dynamics of Longmenshan foreland basin along the eastern margin of the Tibetan Plateau and its coupled relationship with continent collision.Acta Geologica Sinica(in Chinese),80(8):1101-1109.
Li Z W,Liu S G,Chen H D,et al.2008.Structural segmentation and zonation and differential deformation across and along the Longmen thrust belt,West Sichuan,China.Journal of Chengdu University of Technology(Science&Technology Edition)(in Chinese),35(4):440-455.
Lin A M,Rao G,Yan B.2012.Field evidence of rupture of the Qingchuan Fault during the 2008 MW7.9 Wenchuan earthquake,northeastern segment of the Longmen Shan Thrust Belt,China.Tectonophysics,522-523:243-252.
Liu M,Luo G,Wang H.2014.The 2013 Lushan earthquake in China tests hazard assessment.Seismological Research Letters,85(1):40-43,doi:10.1785/0220130117.
Ma B Q,Su G,Hou Z H,et al.2005.Late Quaternary slip rate in the central part of the Longmenshan fault zone from terrace deformation along the Minjiang River.Seismology and Geology(in Chinese),27(2):234-242.
Meade B J.2007.Present-day kinematics at the India-Asia collision zone.Geology,35(1):81-84.
Pan J W,Li H B,Si J L,et al.2014.Rupture process of the Wenchuan earthquake(MW7.9)from surface ruptures and fault striations characteristics.Tectonophysics,619-620:13-28.
Ran Y K,Chen L C,Chen J,et al.2010.Paleoseismic evidence and repeat time of large earthquakes at three sites along the Longmenshan fault zone.Tectonophysics,491(1-4):141-153.
Ran Y K,Chen L C,Chen W S,et al.2012.Key techniques and several cases analysis in paleoseismic studies in mainland China(2):Surface deformation characteristics of Wenchuan earthquake and paleoseismic indicators on fold-reverse fault.Seismology and Geology(in Chinese),33(3):386-400.
Ran Y K,Chen W S,Xu X W,et al.2013.Paleoseismic events and recurrence interval along the Beichuan-Yingxiu fault of Longmenshan fault zone,Yingxiu,Sichuan,China.Tectonophysics,584:81-90.
Ran Y K,Chen W S,Xu X W,et al.2014.Late Quaternary paleoseismic behavior and rupture segmentation of the YingxiuBeichuan fault along the Longmen Shan fault zone,China.Tectonics,33(11):2218-2232,doi:10.1002/2014tc003649.
Shen Z K,Lu J M,Wang M,et al.2005.Contemporary crustal deformation around the southeast borderland of the Tibetan Plateau.Journal of Geophysical Research:Solid Earth,110(B11):B11409,doi:10.1029/2004JB003421.
Shen Z K,Sun J Z,Zhang P Z,et al.2009.Slip maxima at fault junctions and rupturing of barriers during the 2008 Wenchuan earthquake.Nature Geoscience,2(10):718-724.
Shi X,Ran Y K,Chen L C,et al.2009.Preliminary study on paleoearthquake at Beichuan-Dengjia segment along the central fault of Longmen Mountain.Quaternary Sciences(in Chinese),29(3):494-501.
Sun H Y,He H L,Ikeda Y,et al.2015.Holocene paleoearthquake history on the Qingchuan fault in the northeastern segment of the Longmenshan Thrust Zone and its implications.Tectonophysics,660:92-106.
Wang H,Chen L C,Ran Y K,et al.2015.Paleoseismic investigation of the seismic gap between the seismogenic structures of the 2008Wenchuan and 2013Lushan earthquakes along the Longmen Shan fault zone at the eastern margin of the Tibetan Plateau.Lithosphere,7(1):14-20.
Zhang P Z,Xu X W,Wen X Z,et al.2008.Slip rates sand recurrence intervals of the Longmenshan active fault zone,and tectonic implications for the mechanism of the May 12 Wenchuan earthquake,2008,Sichuan,China.Chinese Journal of Geophysics(in Chinese),51(4):1066-1073.
Zhu S B,Zhang P Z.2013.FEM simulation of interseismic and coseismic deformation associated with the 2008 Wenchuan earthquake.Tectonophysics,584:64-80.
陈国光,计凤桔,周荣军等.2007.龙门山断裂带晚第四纪活动性分段的初步研究.地震地质,26(3):657-673.
陈剑.2013.先秦地震考古研究的新进展及其对龙门山地区史前地震考古的启示.民族学刊,4(4):35-53.
陈立春,冉勇康,陈杰等.2009.龙门山前山断裂大地震原地重复发生的地质地貌证据.第四纪研究.29(3):472-483.
陈立春,冉勇康,王虎等.2013.芦山地震与龙门山断裂带南段活动性.科学通报,58(20):1925-1932.
邓起东,陈社发,赵小麟.1994.龙门山及其邻区的构造和地震活动及动力学.地震地质,16(4):389-403.
李传友,宋方敏,冉勇康.2004.龙门山断裂带北段晚第四纪活动性讨论.地震地质,26(2):248-258.
李勇,Allen P A,周荣军等.2006.青藏高原东缘中新生代龙门山前陆盆地动力学及其与大陆碰撞作用的耦合关系.地质学报,80(8):1101-1109.
李智武,刘树根,陈洪德等.2008.龙门山冲断带分段-分带性构造格局及其差异变形特征.成都理工大学学报,35(4):440-454.
马保起,苏刚,侯治华等.2005.利用岷江阶地的变形估算龙门山断裂带中段晚第四纪滑动速率.地震地质,27(2):234-242.
冉勇康,陈立春,陈文山等.2012.中国大陆古地震研究的关键技术与案例解析(2)---汶川地震地表变形特征与褶皱逆断层古地震识别.地震地质,33(3):386-400.
史翔,冉勇康,陈立春等.2009.龙门山中央断裂北川-邓家一带古地震初步研究.第四纪研究,29(3):494-501.
张培震,徐锡伟,闻学泽等.2008.2008年汶川8.0级地震发震断裂的滑动速率、复发周期和构造成因.地球物理学报,51(4):1066-1073.
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