基于非均匀地壳模型的格林函数法反演2001年昆仑山口西Ms8.1地震的同震滑移
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摘要
建立基于地壳不均匀的三维有限元模型,将昆仑山口西Ms8.1地震产生的长约400 km的破裂带在走向上分为16段,生成各个破裂段滑移相对于地表位移的格林函数,并以GPS观测的水平位移为约束,用阻尼最小二乘法反演破裂滑移分布,结果表明反演结果与地质考察的地表破裂数据接近。用反演结果重构的地表位移场与观测值一致,并体现了断裂带南北两侧不同的形变模式。
2001 Kunlun Ms8.1 earthquake ruptured as long as about 400 km.The displacement gradient perpendicular to the strike of rupture belt is significantly greater on the south side than that on the north.This fact cannot be explained by Okada model which is based on elastically homogeneous half space.A horizontally and vertically heterogeneous 3D-FEM model is established to generate Green's functions of slip on 16 segments of the rupture belt with respect to the ground displacement field.With the damping LS(least square) algorithm,the slip distribution of rupture is inversed from observed horizontal displacements of 40 GPS sites,and the result is in good agreement with that from geological field investigation.The ground displacement field rebuilt by the inversed result is close to that observed by GPS,demonstrating different deformation patterns on the two sides of the rupture.
2001 Kunlun Ms8.1 earthquake ruptured as long as about 400 km.The displacement gradient perpendicular to the strike of rupture belt is significantly greater on the south side than that on the north.This fact cannot be explained by Okada model which is based on elastically homogeneous half space.A horizontally and vertically heterogeneous 3D-FEM model is established to generate Green's functions of slip on 16 segments of the rupture belt with respect to the ground displacement field.With the damping LS(least square) algorithm,the slip distribution of rupture is inversed from observed horizontal displacements of 40 GPS sites,and the result is in good agreement with that from geological field investigation.The ground displacement field rebuilt by the inversed result is close to that observed by GPS,demonstrating different deformation patterns on the two sides of the rupture.
引文
1 Lin A,Kikuchi M and Fu B.Rupture segmentation andprocess of the 2001 Mw7.8 central Kunlun earthquake,China[J].Bull Seism Soc Amer.,2003,93:2 477-2 492.
2许力生,陈运泰.用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[J].中国科学(D辑),2004,34(3):256-264.(Xu Lisheng and Chen Yun-tai.Temporal and spatial rupture process of the great KunlunMountain Pass earthquake of Nov.14,2001,from GDSN longperiod waveform data[J].Science in China(Ser D),2004,34(3):256-264)
3徐锡伟,等.2001年11月14日昆仑山库湖地震(Ms8.1)地表破裂带的基本特征[J].地震地质,2002,24(1):1-13.(Xu Xiwei,et al.Characteristic featur es of the surfaceruptures of the HohSai Hu(Kunlunshan)earthquake(Ms8.1)northern Tibetan Plateau,China[J].Seismology andGeology,2002,24(1):1-13)
4 Lin Aiming,et al.Coseismic strikeslip and rupture lengthproduced by the 2001 Ms8.1 central Kunlun earthquake[J].Science,2002,296:2 015-2 017.
5陈杰,等.2001年昆仑山口西Ms8.1地震地表同震位移分布特征[J].地震地质,2004,26(3):378-392.(ChenJie,et al.Surface rupture zones of the 2001 earthquake Ms8.1 west of Kunlun Pass,northern Qinghai-Tibet plateau[J].Quaternary Sciences,2003,23(6):629-639)
6乔学军,等.昆仑山口西Ms8.1地震的地壳变形特征[J].大地测量与地球动力学,2002,(4):6-11.(QiaoXuejun,et al.Characteristics of crustal deformation relatingto Ms8.1 Kunlunshan earthquake[J].Journal of Geodesyand Geodynamics,2002,(4):6-11)
7任金卫,王敏.GPS观测的2001年昆仑山口西Ms8.1地震地壳变形[J].第四纪研究,2005,25(1):34-44.(RenJinwei and Wang Min.GPS measured crustal deformation ofthe Ms8.1 Kunlun earthquake on November 14th 2001 inQinhai-Tibet Plateau[J].Quaternary Sciences,2005,25(1):34-44)
8谭凯,王琪,申重阳.用大地测量数据反演2001年昆仑山地震[J].大地测量与地球动力学,2004,(3):47-50.(Tan Kai,Wang Qi and Shen Chongyang.Using geodetic da-ta to inverse coseismic dislocation of 2001 Kunlun earth-quake[J].Journal of Geodesy and Geodynamics,2004,(3):47-50)
9万永革,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[J].地震地质,2004,26(3):393-404.(Wan Yongge,et al.Co-seismic slip dis-tribution of the 2001 west of kunlun mountain pass earth-quake inverted by GPS and levelling data[J].Seismologyand Geology,2004,26(3):393-404)
10马超,单新建.昆仑山Ms8.1地震震源参数的多破裂段模拟研究[J].地球物理学报,2006,49(2):428-437.(Ma Chao and Shan Xinjian.A multi-segment analytic mod-eling of hypocentral geometric characteristic parameters ofthe Ms8.1 earthquake at the Kunlun mountains[J].Chi-nese J Geophys.,2006,49(2):428-437)
11单新建,柳稼航,马超.2001年昆仑山口西8.1级地震同震形变场特征的初步分析[J].地震学报,2004,26(5):474-480.(Shan Xinjian,Liu Jiahang and Ma Chao.Preliminary analysis on characteristics of coseismic deform-ation associated with Ms8.1 western Kunlunshan Passearthquake in 2001[J].Acta Seimologica Sinica,2004,26(5):474-480)
12吴功建,高锐,钦范.青藏高原“亚东-格尔木地学断面”综合地球物理调查与研究[J].地球物理学报,1991,34(5):552-561.(Wu Gongjian,Gao Rui and Yu Qinfan.Integrated inverstigation of the Qinghai-Tibet plateau a-long the Yadong-Golmud geosciences transect[J].Chi-nese J Geophys.,1991,34(5):552-562)
13 Zhu L and Helmberger D V.Moho offset across the north-ern margin of the Tibetan plateau[J].Science,1998,281:1 170-1 172.
14 Okada Y.Surface deformation due to shear and tensilefaults in a half space[J].Bull seism Soc Am.,1985,75:1 135-1 154.
15王辉,等.昆仑山口西Ms8.1地震同震影响场的数值模拟[J].地震地质,2007,29(3):637-647.(Wang Hui,etal.The numerical simulation on coseismic effect of the 14November 2001 great Kunlun earthquake,Northern Tibet,China[J].Seismology and Geology,2007,29(3):637-647)
16 Masterlark T,Demets C and Wang H F.Homogeneousvsheterogeneous subduction zone models:Coseismic and post-seismic deformation[J].J Geophys Res.,2001,28(21):4 047-4 050.
2许力生,陈运泰.用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[J].中国科学(D辑),2004,34(3):256-264.(Xu Lisheng and Chen Yun-tai.Temporal and spatial rupture process of the great KunlunMountain Pass earthquake of Nov.14,2001,from GDSN longperiod waveform data[J].Science in China(Ser D),2004,34(3):256-264)
3徐锡伟,等.2001年11月14日昆仑山库湖地震(Ms8.1)地表破裂带的基本特征[J].地震地质,2002,24(1):1-13.(Xu Xiwei,et al.Characteristic featur es of the surfaceruptures of the HohSai Hu(Kunlunshan)earthquake(Ms8.1)northern Tibetan Plateau,China[J].Seismology andGeology,2002,24(1):1-13)
4 Lin Aiming,et al.Coseismic strikeslip and rupture lengthproduced by the 2001 Ms8.1 central Kunlun earthquake[J].Science,2002,296:2 015-2 017.
5陈杰,等.2001年昆仑山口西Ms8.1地震地表同震位移分布特征[J].地震地质,2004,26(3):378-392.(ChenJie,et al.Surface rupture zones of the 2001 earthquake Ms8.1 west of Kunlun Pass,northern Qinghai-Tibet plateau[J].Quaternary Sciences,2003,23(6):629-639)
6乔学军,等.昆仑山口西Ms8.1地震的地壳变形特征[J].大地测量与地球动力学,2002,(4):6-11.(QiaoXuejun,et al.Characteristics of crustal deformation relatingto Ms8.1 Kunlunshan earthquake[J].Journal of Geodesyand Geodynamics,2002,(4):6-11)
7任金卫,王敏.GPS观测的2001年昆仑山口西Ms8.1地震地壳变形[J].第四纪研究,2005,25(1):34-44.(RenJinwei and Wang Min.GPS measured crustal deformation ofthe Ms8.1 Kunlun earthquake on November 14th 2001 inQinhai-Tibet Plateau[J].Quaternary Sciences,2005,25(1):34-44)
8谭凯,王琪,申重阳.用大地测量数据反演2001年昆仑山地震[J].大地测量与地球动力学,2004,(3):47-50.(Tan Kai,Wang Qi and Shen Chongyang.Using geodetic da-ta to inverse coseismic dislocation of 2001 Kunlun earth-quake[J].Journal of Geodesy and Geodynamics,2004,(3):47-50)
9万永革,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[J].地震地质,2004,26(3):393-404.(Wan Yongge,et al.Co-seismic slip dis-tribution of the 2001 west of kunlun mountain pass earth-quake inverted by GPS and levelling data[J].Seismologyand Geology,2004,26(3):393-404)
10马超,单新建.昆仑山Ms8.1地震震源参数的多破裂段模拟研究[J].地球物理学报,2006,49(2):428-437.(Ma Chao and Shan Xinjian.A multi-segment analytic mod-eling of hypocentral geometric characteristic parameters ofthe Ms8.1 earthquake at the Kunlun mountains[J].Chi-nese J Geophys.,2006,49(2):428-437)
11单新建,柳稼航,马超.2001年昆仑山口西8.1级地震同震形变场特征的初步分析[J].地震学报,2004,26(5):474-480.(Shan Xinjian,Liu Jiahang and Ma Chao.Preliminary analysis on characteristics of coseismic deform-ation associated with Ms8.1 western Kunlunshan Passearthquake in 2001[J].Acta Seimologica Sinica,2004,26(5):474-480)
12吴功建,高锐,钦范.青藏高原“亚东-格尔木地学断面”综合地球物理调查与研究[J].地球物理学报,1991,34(5):552-561.(Wu Gongjian,Gao Rui and Yu Qinfan.Integrated inverstigation of the Qinghai-Tibet plateau a-long the Yadong-Golmud geosciences transect[J].Chi-nese J Geophys.,1991,34(5):552-562)
13 Zhu L and Helmberger D V.Moho offset across the north-ern margin of the Tibetan plateau[J].Science,1998,281:1 170-1 172.
14 Okada Y.Surface deformation due to shear and tensilefaults in a half space[J].Bull seism Soc Am.,1985,75:1 135-1 154.
15王辉,等.昆仑山口西Ms8.1地震同震影响场的数值模拟[J].地震地质,2007,29(3):637-647.(Wang Hui,etal.The numerical simulation on coseismic effect of the 14November 2001 great Kunlun earthquake,Northern Tibet,China[J].Seismology and Geology,2007,29(3):637-647)
16 Masterlark T,Demets C and Wang H F.Homogeneousvsheterogeneous subduction zone models:Coseismic and post-seismic deformation[J].J Geophys Res.,2001,28(21):4 047-4 050.
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