2001年8.1级昆仑山大震破裂过程及对2008年汶川8.0级大震孕育发生影响的研究
|
摘要
本文用三维流变非连续变形(块体边界)与有限元(块体内)相结合(DDA+FEM)的方法,在青藏高原及其东侧四川盆地,鄂尔多斯块体地区三维构造块体相互制约的大环境中,考虑了龙门山断裂带东西两侧地势、地壳厚度和分层的明显变化,及断裂带东侧四川盆地及鄂尔多斯块体坚硬地壳阻挡的影响,通过用GPS资料做位移速率边界约束和震源机制约束,计算得到研究区的速度场和应力场与该地区GPS测量结果和震源机制分布结果基本相似.在此基础上,数值模拟2001年昆仑山大震的破裂过程;研究大震引起各构造块体边界断层应力状态变化特征,特别是对2008年汶川大震发震断层的影响.结果表明:(1)数值模拟昆仑山大震发震断层发生左旋走滑错动,最大水平错距约4.5 m,最大应力降约18 MPa.计算获得大震释放的主压应力场图像,最大剪应力变化等值线图,大震发震断层垂直面上位错等值线图及大震引起垂直位移变化三维图分别与大震的震源机制,地表破裂带同震位移分布,GPS同震位移图及地震波反演和GPS反演的结果总体上均比较相近.(2)计算获得的最大剪应力变化等值线图分布具有不对称特点,大震发震断层南侧变化梯度明显大于北侧.(3)模拟计算得到大震引起汶川大震发震断层库仑破裂应力增加约0.016 MPa(上地壳层).昆仑山大震破裂过程是在东昆仑断裂带其发震断层上发生的左旋走滑错动,引起东昆仑断裂带南侧巴彦喀拉块体进一步东扩和一定规模的变形,并受到该块体东侧四川盆地较硬地壳的阻挡,使得块体东边界断层中低倾角的汶川大震发震断层库仑破裂应力增大,应变能积累增强.可以认为这一破裂过程对汶川大震发震断层发生逆冲型失稳起了促进作用.
In this paper,3D Finite Element Method combined with Discontinuous Deformation Analysis is used to firstly calculate velocity and stress fields of the Qingzang Plateau in the framework of northward compression of the Indian Plate and obstruction of the strong crust of Sichuan basin,with constraints from GPS data and focal mechanism.Then we simulated the rupture process of the Kunlunshan M_S8.1 earthquake in 2001,and studied the characteristics of stress change on the boundary faults of tectonic blocks caused by the earthquake,especially the influence on the seismogenic fault of the Wenchuan earthquake in 2008.The results show that (1)the Kunlunshan earthquake undergoes sinistral strike-slip movement,the calculated maximum horizontal dislocation of the seismogenic fault is 4.5 m,and the calculated maximum stress drop is 18 MPa.The distribution of principal compressive stress change,the contour map of maximum shear stress change before and after Kunlunshan earthquake,the 3D distribution of the vertical displacement caused by the earthquake acquired via calculation are totally in agreement with the focal mechanism solution,the coseismic displacement distribution on the rupture zone of the earthquake.(2)The maximum shear stress variation on the north and south sides of the seismogenic fault is asymmetrical,with the stress change gradient on the south side much greater than that on the north side.(3)We find that the Kunlunshan earthquake caused the Coulomb failure stress increase 0.016 MPa(upper crust)on the seismogenic fault of the 2008 Wenchuan earthquake.The rupture process of Kunlunshan earthquake,a sinistral strike-slip movement on the seismic fault of eastern Kunlun fracture zone,caused Bayankala block at southern side of eastern Kunlun fracture zone to extend further to east and deform to a certain extent.Meanwhile,the obstruction of stronger crust in Sichuan basin at eastern side of Bayankala block made the Coulomb failure stress increase and strain energy accumulation strengthen,on seismic fault of Wenchuan earthquake with low dip angle at eastern boundary of the block.Therefore,the occurrence of the Kunlunshan earthquake has played a role of promoting the generation and instability of the seismogenic fault of the Wenchuan earthquake.
In this paper,3D Finite Element Method combined with Discontinuous Deformation Analysis is used to firstly calculate velocity and stress fields of the Qingzang Plateau in the framework of northward compression of the Indian Plate and obstruction of the strong crust of Sichuan basin,with constraints from GPS data and focal mechanism.Then we simulated the rupture process of the Kunlunshan M_S8.1 earthquake in 2001,and studied the characteristics of stress change on the boundary faults of tectonic blocks caused by the earthquake,especially the influence on the seismogenic fault of the Wenchuan earthquake in 2008.The results show that (1)the Kunlunshan earthquake undergoes sinistral strike-slip movement,the calculated maximum horizontal dislocation of the seismogenic fault is 4.5 m,and the calculated maximum stress drop is 18 MPa.The distribution of principal compressive stress change,the contour map of maximum shear stress change before and after Kunlunshan earthquake,the 3D distribution of the vertical displacement caused by the earthquake acquired via calculation are totally in agreement with the focal mechanism solution,the coseismic displacement distribution on the rupture zone of the earthquake.(2)The maximum shear stress variation on the north and south sides of the seismogenic fault is asymmetrical,with the stress change gradient on the south side much greater than that on the north side.(3)We find that the Kunlunshan earthquake caused the Coulomb failure stress increase 0.016 MPa(upper crust)on the seismogenic fault of the 2008 Wenchuan earthquake.The rupture process of Kunlunshan earthquake,a sinistral strike-slip movement on the seismic fault of eastern Kunlun fracture zone,caused Bayankala block at southern side of eastern Kunlun fracture zone to extend further to east and deform to a certain extent.Meanwhile,the obstruction of stronger crust in Sichuan basin at eastern side of Bayankala block made the Coulomb failure stress increase and strain energy accumulation strengthen,on seismic fault of Wenchuan earthquake with low dip angle at eastern boundary of the block.Therefore,the occurrence of the Kunlunshan earthquake has played a role of promoting the generation and instability of the seismogenic fault of the Wenchuan earthquake.
引文
[1] 许力生,陈运泰.从全球长周期波形资料反演2001年11月14日昆仑山口地震时空破裂过程.中国科学(D辑),2004,(3) :256～264 Xu L S,Chen Y T.Tempo-spatial rupture process of the 14 November 2001,Kunlunshan earthquake using long period wave form data.Science in China (D) (in Chinese),2004,34(3) :256～264
[2] Lin A,Fu B,Guo J,et al.Coseismic strike-slip and rupture length produced by the 2001 M_s8． 1 Central Kunlunshan earthquake.Science,2002,296:2015～2017
[3] 周云好,陈章立,缪发军等.2001年11月14日昆仑山口西M_s8． 1地震震源破裂过程研究.地震学报,2004,26(增):9～20 Zhou Y H,Chen Z L,Miao F J,et al.Source process of the 14 November 2001 westhern Kunlunshan Mountain M_s8． 1 earthquake.Acta Seismologica Sinica (in Chinese),2004,26(Suppl.):9～20
[4] Van der Woerd J,Meriaux A S,Klinger Y,et al.The 14 November 2001,M_w=7． 8 Kokoxili earthquake in northern Tibet (Qinghai Province,China).Seism.Res.Lett.,2002,73:125～135
[5] 张培震,邓起东,张国民等.中国大陆的强震活动与活动地块.中国科学(D辑),2003,46(增刊):13～24 Zhang P Z,Deng Q D,Zhang G M,et al.Active tectonic blocks and strong earthquakes in the continent of China.Science in China (D) (in Chinese) ,2003,46(Suppl.) :13～24
[6] Shi G,Goodman R E.Discontinuous deformation analysis:A new method for computing stress,strain and sliding of block system.Proceedings of the 29~(th) U.S.Symposium on Key Question in the Rock Mechanics,1988． 381～393
[7] Cai Y,He T,Wang R.Numerical simulation of dynamics process of the Tangshan earthquake by a new method-LDDA.Pure Appl.Geophys.,2000,157:2083～2104
[8] 白武明,林邦慧,陈祖安.1976年唐山大震发生对华北地区各地块运动与变形影响的数值模拟研究.中国科学,2003,33(增刊):99～107+211 Bai W M,Lin B H,Chen Z A.Numerical simulations of deformation and movement of blocks within North China in response to 1976 Tangshan earthquake.Science in China (D),2003,46(Suppl.):141～152
[9] 陈祖安,白武明,林邦慧等.1966年以来华北地区一系列七级大震破裂过程的数值模拟.地球物理学报,2003,46(3) :373～381 Chen Z A,Bai W M,Lin B H,et al.Numerical simulation lor rupture processes of a series of strong earthquakes (M_s>7) in North China since 1966． Chinese J.Geophys.(in Chinese),2003,46(3) :373～381
[10] 陈祖安,林邦慧,白武明.1997年玛尼地震发生对青藏川滇地区构造块体系统稳定性影响的三维DDA+FEM方法数值模拟.地球物理学报,2008,51(5) :1422～1430 Chen Z A,Lin B H,Bai W M.3-D numerical simulation on influence of 1997 Mani earthquake to stability of tectonic blocks system in Qingzang and Chuandian regions.Chinese J.Geophys.(in Chinese) ,2008,51(5) :1422～1430
[11] 陈祖安,林邦慧,白武明等.2008年汶川M_s8． 0级地震孕育机理研究.地球物理学报,2009,52(2) :408～417 Chen Z A,Lin B H,Bai W M,et al.The mechanism of generation of May 12,2008 M_s8． 0 Wenchuan earthquake.Chinese J.Geophys.(in Chinese) ,2009,52(2) :408～417
[12] Peric D,Owen D R J.Computational model for 3-D contact problems with friction based on the penalty method.Int.J.Num.Mech.Eng.,1992,35:289～1309
[13] Zienkiewicz O C,Taylor R L.The Finite Element Method for Solid and Structural Mechanics.Beijing:Printed in China by Elsevier (Singapore) Pte Ltd.under Beijing World Publishing Corporation,2009
[14] 陈运泰,许力生,张勇等.2008年5月12日汶川特大地震震源特性分析报告.2008,http://www.csi.ac.cn/sichuan/ chenyuntai.pdf Chen Y T,Xu L S,Zhang Y,et al.An analytical report on seismic source characteristic of May 12,2008 Whenchuan earthquake.2008,http://www.csi.ac.cn/sichuan/chenyuntai.pdf
[15] 腾吉文,白登海,杨 辉等.2008汶川M_s8． 0地震发生的深层过程和动力学响应.地球物理学报,2008,51(5) :1385～1402 Teng J W,Bai D H,Yang H,et al.Deep process and dynamic responses associated with the Wenchuan M_s8． 0 earthquake of 2008． Chinese].Geophys.(in Chinese),2008,51(5) :1385～1402
[16] 王卫民,赵连锋,李娟等.四川汶川8． 0级地震震源过程.地球物理学报,2008,51(5) :1403～1410 Wang W M,Zhao L F,Li J,et al.Rupture process of the M_s8． 0 Wenchuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5) :1403～1410
[17] Burchfiel B C,Royden L H,Van der Hilst R D,et al.A geological and Geophysical context for the Wenchuan earthquake of 12 May 2008,Sichuan,People's Republic of China.GSA Today ,2008,18(7) :4～11
[18] 滕吉文.固体地球物理学概论.北京:地震出版社,2003 Teng J W.Introduction to Solid Geophysics (in Chinese).Beijing;Seismological Press,2003
[19] 刘启元,陈九辉,李顺成等.汶川M_s8． 0地震:川西流动地震台阵观测数据的初步分析.地震地质,2008,30(3) :584～596 Liu Q Y,Chen J H,Li S C,et al.The M_s8． 0 Wenchan earthquake:preliminary results from the western Sichuan mobile seismic array observations.Seismology and Geology (in Chinese),2008,30(3) :584～596
[20] 丁志峰,何正勤,吴建平等.青藏高原地震波三维速度结构的研究.中国地震,2001,17(2) :202～209 Ding Z F,He Z Q,Wu J P,et al.Research on the 3-D seismic velocity structures in Qinghai-Xizang plateau.Earthquake Research in China (in Chinese),2001,17(2) :202～209
[21] 王椿镛,吴建平,楼海等.川西藏东地区的地壳P波速度结构.中国科学(D辑),2003,46(增):254～265 Wang C Y,Wu J P,Lou H,et al.P-wave crustal velocity structure in western Sichuan and eastern Tibetan region.Science in China (D) (in Chinese),2003,46(Suppl.):254～265
[22] 王椿镛,吴建平,楼海等.青藏高原东部壳幔速度结构和地幔变形场的研究.地学前缘,2006,13(5) :349～259 Wang C Y,Wu J P,Lou H,et al.Study of crustal and upper mantle s structure and mantle deformation field beneath the eastern Tibetan plateau.Earth Science Frontiers (in Chinese) ,2006,13(5) :349～259
[23] 楼海,王椿镛,吕智勇等.2008年汶川M_s8． 0级地震的深部构造环境-远震P波接收函数和布格重力异常的联合解释.中国科学(D辑),2008,38(10) :1207～1220 Lou H,Wang C Y,L(u|¨) Z Y,et al.Deep tectonic setting of the 2008 Wenchuan M_s8． 0 earthquake in southwestern China-Joint analysis of teleseimic P-wave receiver functions and Bouguer gravity anomalies.Science in China (D) (in Chinese) ,2008,38(10) :1207～1220
[24] 李永华,吴庆举,安张辉等.青藏高原东北缘地壳S波速度结构与泊松比及其意义.地球物理学报,2006,49(5) :1359～1368 Li Y H,Wu Q J,An Z H,et al.The Posisson ratio and crustal structure across the NE Tibetan Plateau determined from receiver functions.Chinese J.Geophys.(in Chinese) ,2006,49(5) :1359～1368
[25] Zhang P Z,Shen Z,Wang M,et al.Continuous deformation of the Tibetan Plateau from global positioning system data.Geology,2004,32:809～812
[26] 许忠淮.东亚地区现今构造应力图的编制.地震学报,2001,23(5) :492～501 Xu Z H.A present-day tectonic stress map for eastern Asia region.Acta Seismologica Sinica (in Chinese),2001,23(5) :492～501
[27] 徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库赛湖地震(M_s8． 1) 地表破裂带的基本特征.地震地质,2002,24(1) :1～13+133～136
Xu X W,Chen W B,Yu G H,et al.Characteristic features of the surface rupture of the Hoh Sai Hu (Kunlunshanshan) earthquake (M_s8． 1) ,northern Tibetan Plateau,China.Seism.Geol.(in Chinese),2002,24:1～13 + 133～136
[28] 万永革,王敏,沈正康等.利用GPS和水准测量资料反演2001年昆仑山口西8． 1级地震的同震滑动分布.地震地质,2004,26(3) :393～404 Wan Y G,Wang M,Shen Z K,et al.Coseismic slip distribution of the 2001 west of Kunlun Mountain Pass earthquake inverted by GPS and leveling data.Seismology and Geology (in Chinese),2004 ,26(3) :393～404
[29] 沈正康,万永革,甘卫军等.东昆仑活动断裂带大地震之间的黏弹性应力触发研究.地球物理学报,2003,46(6) :786～795 Shen Z K,Wan Y G,Gan W J,et al.Viscoelastic triggering among large earthquakes along the east Kunlunshan fault system.Chinese J.Geophys.(in Chinese),2003,46(6) :786～795
[2] Lin A,Fu B,Guo J,et al.Coseismic strike-slip and rupture length produced by the 2001 M_s8． 1 Central Kunlunshan earthquake.Science,2002,296:2015～2017
[3] 周云好,陈章立,缪发军等.2001年11月14日昆仑山口西M_s8． 1地震震源破裂过程研究.地震学报,2004,26(增):9～20 Zhou Y H,Chen Z L,Miao F J,et al.Source process of the 14 November 2001 westhern Kunlunshan Mountain M_s8． 1 earthquake.Acta Seismologica Sinica (in Chinese),2004,26(Suppl.):9～20
[4] Van der Woerd J,Meriaux A S,Klinger Y,et al.The 14 November 2001,M_w=7． 8 Kokoxili earthquake in northern Tibet (Qinghai Province,China).Seism.Res.Lett.,2002,73:125～135
[5] 张培震,邓起东,张国民等.中国大陆的强震活动与活动地块.中国科学(D辑),2003,46(增刊):13～24 Zhang P Z,Deng Q D,Zhang G M,et al.Active tectonic blocks and strong earthquakes in the continent of China.Science in China (D) (in Chinese) ,2003,46(Suppl.) :13～24
[6] Shi G,Goodman R E.Discontinuous deformation analysis:A new method for computing stress,strain and sliding of block system.Proceedings of the 29~(th) U.S.Symposium on Key Question in the Rock Mechanics,1988． 381～393
[7] Cai Y,He T,Wang R.Numerical simulation of dynamics process of the Tangshan earthquake by a new method-LDDA.Pure Appl.Geophys.,2000,157:2083～2104
[8] 白武明,林邦慧,陈祖安.1976年唐山大震发生对华北地区各地块运动与变形影响的数值模拟研究.中国科学,2003,33(增刊):99～107+211 Bai W M,Lin B H,Chen Z A.Numerical simulations of deformation and movement of blocks within North China in response to 1976 Tangshan earthquake.Science in China (D),2003,46(Suppl.):141～152
[9] 陈祖安,白武明,林邦慧等.1966年以来华北地区一系列七级大震破裂过程的数值模拟.地球物理学报,2003,46(3) :373～381 Chen Z A,Bai W M,Lin B H,et al.Numerical simulation lor rupture processes of a series of strong earthquakes (M_s>7) in North China since 1966． Chinese J.Geophys.(in Chinese),2003,46(3) :373～381
[10] 陈祖安,林邦慧,白武明.1997年玛尼地震发生对青藏川滇地区构造块体系统稳定性影响的三维DDA+FEM方法数值模拟.地球物理学报,2008,51(5) :1422～1430 Chen Z A,Lin B H,Bai W M.3-D numerical simulation on influence of 1997 Mani earthquake to stability of tectonic blocks system in Qingzang and Chuandian regions.Chinese J.Geophys.(in Chinese) ,2008,51(5) :1422～1430
[11] 陈祖安,林邦慧,白武明等.2008年汶川M_s8． 0级地震孕育机理研究.地球物理学报,2009,52(2) :408～417 Chen Z A,Lin B H,Bai W M,et al.The mechanism of generation of May 12,2008 M_s8． 0 Wenchuan earthquake.Chinese J.Geophys.(in Chinese) ,2009,52(2) :408～417
[12] Peric D,Owen D R J.Computational model for 3-D contact problems with friction based on the penalty method.Int.J.Num.Mech.Eng.,1992,35:289～1309
[13] Zienkiewicz O C,Taylor R L.The Finite Element Method for Solid and Structural Mechanics.Beijing:Printed in China by Elsevier (Singapore) Pte Ltd.under Beijing World Publishing Corporation,2009
[14] 陈运泰,许力生,张勇等.2008年5月12日汶川特大地震震源特性分析报告.2008,http://www.csi.ac.cn/sichuan/ chenyuntai.pdf Chen Y T,Xu L S,Zhang Y,et al.An analytical report on seismic source characteristic of May 12,2008 Whenchuan earthquake.2008,http://www.csi.ac.cn/sichuan/chenyuntai.pdf
[15] 腾吉文,白登海,杨 辉等.2008汶川M_s8． 0地震发生的深层过程和动力学响应.地球物理学报,2008,51(5) :1385～1402 Teng J W,Bai D H,Yang H,et al.Deep process and dynamic responses associated with the Wenchuan M_s8． 0 earthquake of 2008． Chinese].Geophys.(in Chinese),2008,51(5) :1385～1402
[16] 王卫民,赵连锋,李娟等.四川汶川8． 0级地震震源过程.地球物理学报,2008,51(5) :1403～1410 Wang W M,Zhao L F,Li J,et al.Rupture process of the M_s8． 0 Wenchuan earthquake of Sichuan,China.Chinese J.Geophys.(in Chinese),2008,51(5) :1403～1410
[17] Burchfiel B C,Royden L H,Van der Hilst R D,et al.A geological and Geophysical context for the Wenchuan earthquake of 12 May 2008,Sichuan,People's Republic of China.GSA Today ,2008,18(7) :4～11
[18] 滕吉文.固体地球物理学概论.北京:地震出版社,2003 Teng J W.Introduction to Solid Geophysics (in Chinese).Beijing;Seismological Press,2003
[19] 刘启元,陈九辉,李顺成等.汶川M_s8． 0地震:川西流动地震台阵观测数据的初步分析.地震地质,2008,30(3) :584～596 Liu Q Y,Chen J H,Li S C,et al.The M_s8． 0 Wenchan earthquake:preliminary results from the western Sichuan mobile seismic array observations.Seismology and Geology (in Chinese),2008,30(3) :584～596
[20] 丁志峰,何正勤,吴建平等.青藏高原地震波三维速度结构的研究.中国地震,2001,17(2) :202～209 Ding Z F,He Z Q,Wu J P,et al.Research on the 3-D seismic velocity structures in Qinghai-Xizang plateau.Earthquake Research in China (in Chinese),2001,17(2) :202～209
[21] 王椿镛,吴建平,楼海等.川西藏东地区的地壳P波速度结构.中国科学(D辑),2003,46(增):254～265 Wang C Y,Wu J P,Lou H,et al.P-wave crustal velocity structure in western Sichuan and eastern Tibetan region.Science in China (D) (in Chinese),2003,46(Suppl.):254～265
[22] 王椿镛,吴建平,楼海等.青藏高原东部壳幔速度结构和地幔变形场的研究.地学前缘,2006,13(5) :349～259 Wang C Y,Wu J P,Lou H,et al.Study of crustal and upper mantle s structure and mantle deformation field beneath the eastern Tibetan plateau.Earth Science Frontiers (in Chinese) ,2006,13(5) :349～259
[23] 楼海,王椿镛,吕智勇等.2008年汶川M_s8． 0级地震的深部构造环境-远震P波接收函数和布格重力异常的联合解释.中国科学(D辑),2008,38(10) :1207～1220 Lou H,Wang C Y,L(u|¨) Z Y,et al.Deep tectonic setting of the 2008 Wenchuan M_s8． 0 earthquake in southwestern China-Joint analysis of teleseimic P-wave receiver functions and Bouguer gravity anomalies.Science in China (D) (in Chinese) ,2008,38(10) :1207～1220
[24] 李永华,吴庆举,安张辉等.青藏高原东北缘地壳S波速度结构与泊松比及其意义.地球物理学报,2006,49(5) :1359～1368 Li Y H,Wu Q J,An Z H,et al.The Posisson ratio and crustal structure across the NE Tibetan Plateau determined from receiver functions.Chinese J.Geophys.(in Chinese) ,2006,49(5) :1359～1368
[25] Zhang P Z,Shen Z,Wang M,et al.Continuous deformation of the Tibetan Plateau from global positioning system data.Geology,2004,32:809～812
[26] 许忠淮.东亚地区现今构造应力图的编制.地震学报,2001,23(5) :492～501 Xu Z H.A present-day tectonic stress map for eastern Asia region.Acta Seismologica Sinica (in Chinese),2001,23(5) :492～501
[27] 徐锡伟,陈文彬,于贵华等.2001年11月14日昆仑山库赛湖地震(M_s8． 1) 地表破裂带的基本特征.地震地质,2002,24(1) :1～13+133～136
Xu X W,Chen W B,Yu G H,et al.Characteristic features of the surface rupture of the Hoh Sai Hu (Kunlunshanshan) earthquake (M_s8． 1) ,northern Tibetan Plateau,China.Seism.Geol.(in Chinese),2002,24:1～13 + 133～136
[28] 万永革,王敏,沈正康等.利用GPS和水准测量资料反演2001年昆仑山口西8． 1级地震的同震滑动分布.地震地质,2004,26(3) :393～404 Wan Y G,Wang M,Shen Z K,et al.Coseismic slip distribution of the 2001 west of Kunlun Mountain Pass earthquake inverted by GPS and leveling data.Seismology and Geology (in Chinese),2004 ,26(3) :393～404
[29] 沈正康,万永革,甘卫军等.东昆仑活动断裂带大地震之间的黏弹性应力触发研究.地球物理学报,2003,46(6) :786～795 Shen Z K,Wan Y G,Gan W J,et al.Viscoelastic triggering among large earthquakes along the east Kunlunshan fault system.Chinese J.Geophys.(in Chinese),2003,46(6) :786～795
版权所有：© 2023 中国地质图书馆 中国地质调查局地学文献中心