2008年汶川8.0级地震地表垂直和水平位移场模拟计算分析
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摘要
本文采用Okada及Steketee的断裂位错模型,从理论上计算了龙门山中央主断裂和前山断裂在汶川地震中逆冲和走滑错动形成的地表位移场,包括地表垂直和水平位移场的基本特征。并将计算结果与地震科考成果进行了比较,发现计算结果与现场地表变形考察结果在变化趋势上表现出一致性。同时通过计算揭示了断裂错动过程中离断裂一定范围内的地表位移场变化情况,计算结果表明断裂错动形成的地表垂直存在较大的空间不均匀性,且主要集中于断裂的端部即映秀、北川和青川附近,并且位移场在这些地方变化都较强烈。水平位移场主要集中于北川以北的地区,水平位移场的空间变化比较均匀。
By using fault dislocation model proposed by Yoshimitsu Okada and Steketee, we calculate the vertical and horizontal displacements along Yingxiu-Beichuan reverse fault and Guanxian-Anxian reverse fault along which Wenchuan MS8.0 earthquake occurred in 2008. Comparing with the results from field survey along the surface rupture zone, we find that our computational results are comparable to the reality in displacement variation trend. Furthermore, the computational results indicate that the surface displacement fields varies with the distance form the fault, and the vertical displacement fields show strong inhomogeneity, in which largen displacement focuses on the ends of fault. However, in contrast to the vertical displacement, the horizontal displacement shows relative uniformity in space.
By using fault dislocation model proposed by Yoshimitsu Okada and Steketee, we calculate the vertical and horizontal displacements along Yingxiu-Beichuan reverse fault and Guanxian-Anxian reverse fault along which Wenchuan MS8.0 earthquake occurred in 2008. Comparing with the results from field survey along the surface rupture zone, we find that our computational results are comparable to the reality in displacement variation trend. Furthermore, the computational results indicate that the surface displacement fields varies with the distance form the fault, and the vertical displacement fields show strong inhomogeneity, in which largen displacement focuses on the ends of fault. However, in contrast to the vertical displacement, the horizontal displacement shows relative uniformity in space.
引文
陈运泰,许力生,张勇等,2008.2008年5月12日汶川特大地震震源特性分析报告.http://www.csi.ac.cn/sichuan/chenyuntai.pdf.
陈桂华,徐锡伟,郑荣章等,2008.2008年汶川MS8.0地震地表破裂变形定量分析——北川-映秀断裂地表破裂带.地震地质,30(3):723—738.
陈国光等,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,29(3):657—673.
李智武,刘学根等,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(自然科学版),35(4):440—454.
刘静,张智慧等,2008.汶川8级大地震同震破裂的特殊性及构造意义.地质学报,82(12):1707—1722.
龙学明,罗志立,1994.龙门山冲断带的分区及其演化.龙门山造山带的崛起和四川盆地的形成与演化.成都:成都科技大学出版社.
唐荣昌,文德华,黄祖智等,1991.松潘-龙门山地区主要活动断裂带第四纪活动特征.中国地震,7(3):64—71.
王卫民,姚振兴,2008.再谈汶川8.0级地震震源破裂过程.http://www.csi.ac.cn/sichuan/sichuan050512_110.htm
徐锡伟,闻学泽等,2008.汶川MS8.0地震地表破裂带及其发震构造.地震地质,30(3):597—629.
杨晓平,冯希杰等,2008.龙门山断裂带北段第四纪活动的地质地貌证据.地震地质,30(3):644—657.
张永志,罗凌燕,王卫东,2008.位错理论在西安地面沉降模拟中的应用.西北地震学报,30(1):17—20.
周庆,徐锡伟等,2008.汶川8.0级地震地表破裂带宽度调查.地震地质,30(3):778—787.
Chinnery M.A.,1961.The deformation of ground around surface faults.Bull.Seism.Soc.Am.,51:355—372.
Chinnery M.A.,1963.The stress changes that accompany strike-slip faulting.Bull.Seism.Soc.Am.,53:921—931.
Converse G.,1973.Equations for the displacements and displacement derivatives due to a rectangular dislocation in a three-dimensional elastic half-space,User’s Manual for DIS3D.U.S.Geological Survey,Menlo Park,119—148.
Iwasaki T.and R.Sato,1979.Strain field in a semi-infinite medium due to an inclined rectangular fault.J.Phys.Earth,27:285—314.
Ji C.H.,2008.Preliminary result of the May12,2008MW7.9Eastern Sichuan.China Earthquake.http://earth quake.usgs.gov/eqcenter/eqin the news/2008/us2008ryan/finite_fault.php.
Mansinha L.and Smylie D.E.,1967.Effect of earthquakes on the Chandler wobble and the secular polar shift.J.Geophys.Res.,72:4731—4743.
Mansinha L.and Smylie D.E.,1971.The displacement fields of inclined faults.Bull.Seism.Soc.Am.,61:1433—1440.
Okada Y.,1985.Surface deformation due to shear and tensile faults in a half-space.Bul1.Seis.Soc.Am.,75:1135—1154.
Okada Y.,1992.Internal deformation due to shear and tensile faults in a half-space.Bull.Seism.Soc.Am.,82:1018—1040.
Parsons T.,Chen J.and Kirby E.,2008.Stress changes from the2008Wenchuan earthquake and increased hazard in the Sichuan Basin.Nature,doi.10.1038/nature07177.
Steketee J.A.,1958.On Voherra's dislocation in a semi-infinite elastic medium.Can.J.Phys.,36:192—205.
陈桂华,徐锡伟,郑荣章等,2008.2008年汶川MS8.0地震地表破裂变形定量分析——北川-映秀断裂地表破裂带.地震地质,30(3):723—738.
陈国光等,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,29(3):657—673.
李智武,刘学根等,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(自然科学版),35(4):440—454.
刘静,张智慧等,2008.汶川8级大地震同震破裂的特殊性及构造意义.地质学报,82(12):1707—1722.
龙学明,罗志立,1994.龙门山冲断带的分区及其演化.龙门山造山带的崛起和四川盆地的形成与演化.成都:成都科技大学出版社.
唐荣昌,文德华,黄祖智等,1991.松潘-龙门山地区主要活动断裂带第四纪活动特征.中国地震,7(3):64—71.
王卫民,姚振兴,2008.再谈汶川8.0级地震震源破裂过程.http://www.csi.ac.cn/sichuan/sichuan050512_110.htm
徐锡伟,闻学泽等,2008.汶川MS8.0地震地表破裂带及其发震构造.地震地质,30(3):597—629.
杨晓平,冯希杰等,2008.龙门山断裂带北段第四纪活动的地质地貌证据.地震地质,30(3):644—657.
张永志,罗凌燕,王卫东,2008.位错理论在西安地面沉降模拟中的应用.西北地震学报,30(1):17—20.
周庆,徐锡伟等,2008.汶川8.0级地震地表破裂带宽度调查.地震地质,30(3):778—787.
Chinnery M.A.,1961.The deformation of ground around surface faults.Bull.Seism.Soc.Am.,51:355—372.
Chinnery M.A.,1963.The stress changes that accompany strike-slip faulting.Bull.Seism.Soc.Am.,53:921—931.
Converse G.,1973.Equations for the displacements and displacement derivatives due to a rectangular dislocation in a three-dimensional elastic half-space,User’s Manual for DIS3D.U.S.Geological Survey,Menlo Park,119—148.
Iwasaki T.and R.Sato,1979.Strain field in a semi-infinite medium due to an inclined rectangular fault.J.Phys.Earth,27:285—314.
Ji C.H.,2008.Preliminary result of the May12,2008MW7.9Eastern Sichuan.China Earthquake.http://earth quake.usgs.gov/eqcenter/eqin the news/2008/us2008ryan/finite_fault.php.
Mansinha L.and Smylie D.E.,1967.Effect of earthquakes on the Chandler wobble and the secular polar shift.J.Geophys.Res.,72:4731—4743.
Mansinha L.and Smylie D.E.,1971.The displacement fields of inclined faults.Bull.Seism.Soc.Am.,61:1433—1440.
Okada Y.,1985.Surface deformation due to shear and tensile faults in a half-space.Bul1.Seis.Soc.Am.,75:1135—1154.
Okada Y.,1992.Internal deformation due to shear and tensile faults in a half-space.Bull.Seism.Soc.Am.,82:1018—1040.
Parsons T.,Chen J.and Kirby E.,2008.Stress changes from the2008Wenchuan earthquake and increased hazard in the Sichuan Basin.Nature,doi.10.1038/nature07177.
Steketee J.A.,1958.On Voherra's dislocation in a semi-infinite elastic medium.Can.J.Phys.,36:192—205.
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