2015年尼泊尔地震M_w7.9产生的地球内部变形
|
摘要
针对地球内部变形的理论研究缺失,该文基于半无限空间的地球模型,研究了2015年尼泊尔地震M_w7.9产生的地球内部不同深处(地表以及地下10、20、30、50、100和300km)的同震位移变化,研究区域内的地表最大垂直位移有0.779 0m,向下的最大垂直位移是-0.383m,南北向的水平位移在断层处产生集中挤压,最大值有1.460 0m,这与尼泊尔境内的GPS观测结果比较吻合;地下10km处的位移比地表的变形要大很多;地球深部的位移结果逐渐变小,并且100km处的水平位移方向也发生了巨大变化。地球内部位移变化结果显示:地球浅部位移与地表的走向趋势一致但振幅不同,地表的位移并不是最大的,接近震源处的变形最大。
According to the lack of the research on the inner deformation in the Earth,this paper studied the inner coseismic displacements in the Earth(surface and below at 10,20,30,50,100 and 300 km)caused by the 2015 Nepal earthquake M_w7.9 based on the half-space Earth model.The max vertical displacement was 0.779 0 mand the maximum downward displacement was-0.383 min the study area.The horizontal displacements were concentrated on the finite fault,the maximum was 1.460 0 m,which is agree well with the GPS data.The displacements at 10 km under the surface were bigger than the surface.The displacements decrease with the depth in the Earth,the directions of the horizontal displacements at 100 km had changed a lot.The results of the inner deformation indicate the trends of the displacements at shallow of the Earth were same as the surface,but the amplitude was different.The deformation on the surface was not the largest,but which around the epicenter.
According to the lack of the research on the inner deformation in the Earth,this paper studied the inner coseismic displacements in the Earth(surface and below at 10,20,30,50,100 and 300 km)caused by the 2015 Nepal earthquake M_w7.9 based on the half-space Earth model.The max vertical displacement was 0.779 0 mand the maximum downward displacement was-0.383 min the study area.The horizontal displacements were concentrated on the finite fault,the maximum was 1.460 0 m,which is agree well with the GPS data.The displacements at 10 km under the surface were bigger than the surface.The displacements decrease with the depth in the Earth,the directions of the horizontal displacements at 100 km had changed a lot.The results of the inner deformation indicate the trends of the displacements at shallow of the Earth were same as the surface,but the amplitude was different.The deformation on the surface was not the largest,but which around the epicenter.
引文
[1]AMMON C J,JI C,THIO H,et al.Rupture process of the 2004Sumatra-Andaman earthquake[J].Science,2005,308(5725):1133-1139.
[2]BANERJEE P,POLLITZ F F,BURGMANN R.The size and duration of the Sumatra-Andaman earthquake from far-field static offsets[J].Science,2005,308(5729):1769-1772.
[3]WANG M,LI Q,WANG F,et al.Far-field coseismic displacements associated with the 2011 Tohoku-Oki earthquake in Japan observed by global positioning system[J].Chinese Science Bulletin,2011,56(23):2419-2424.
[4]ARAYA A,MORI W,HAYAKAWA H,et al.Astrain step observed by a laser strainmeter in Kamioka[J].Chikyu Monthly,Supplement,2006,56:104-110.
[5]STEKETEE J A.On Volterra’s dislocation in a semiinfinite elastic medium[J].Canadian Journal of Physics,1958,36(2):192-205.
[6]CHINNERY M A.The deformation of ground around surface faults[J].Bulletin of the Seismological Society of America,1961,51(3):355-372.
[7]CHINNERY M A.The stress changes that accompany strike-slip faulting[J].Bulletin of the Seismological Society of America,1963,53(5):921-932.
[8]MARUYAMA T.Statical elastic dislocations in an infinite and semi-infinite medium[J].Bulletin Earthquake Research Institute,University of Tokyo,1964,42:289-368.
[9]PRESS F.Displacements,strains and tilts at teleseismic distances[J].Journal of Geophysical Research,1965,70(10):2395-2412.
[10]OKADA Y.Surface deformation due to shear and tensile faults in a halfspace[J].Bulletin Seismological Society of America,1985,75(4):1135-1154.
[11]OKADA Y.Internal deformation due to shear and tensile faults in a half-space[J].Bulletin Seismological Society of America,1992,82(2):1018-1040.
[12]SATO R.Crustal deformation due to a dislocation in a multi-layered medium[J].Journal of Physical of the Earth,1971,19(1):31-46.
[13]JOVANOVICH D B,HUSSEINI M I,CHINNERY MA.Elastic dislocations in a layered half-space:I.basic theory and numerical methods[J].Geophysical Journal Royal Astronomical Society,1974,39(2):205-217.
[14]JOVANOVICH D B,HUSSEINI M I,CHINNERY MA.Elastic dislocations in a layered half-space:II.the point source[J].Geophysical Journal Royal Astronomical Society,1974,39(2):219-239.
[15]WANG R J,MARTIN F L,ROTH F.Computation of deformation induced by earthquakes in a multi-layered elastic crust:FORTRAN programs EDGRN/EDCMP[J].Computers&Geoscience,2003,29(2):195-207.
[16]WANG R J,MARTIN F L,ROTH F.PSGRN/PSCMP:a new code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geoscience,2006,32(4):527-541.
[17]BEN-MENAHEM A,SINGH S J.Eigenvector expansions of Green’s dyads with applications to geophysical theory[J].Geophysical Journal International,1968,16(4):417-452.
[18]BEN-MENAHEM A,SINGH S J,SOLOMON F.Static deformation of a spherical earth model by internal dislocations[J].Bulletin Seismological Society of America,1969,59(2):813-853.
[19]SUN W K,OKUBO S.Surface potential and gravity changes due to internal dislocations in a spherical Earth,Ⅰ.theory for a point dislocation[J].Geophysical Journal International,1993,114(3):569-592.
[20]SUN W K,OKUBO S,FU G Y,et al.General formulations of global co-seismic deformations caused by an arbitrary dislocation in a spherically symmetric earth model:applicable to deformed earth surface and spacefixed point[J].Geophysical Journal International,2009,177(3):817-833.
[21]POLLITZ F F.Postseismic relaxation theory on the spherical Earth[J].Bulletin Seismological Society of America,1992,82(1):422-453.
[22]HAN D,WAHR J.The viscoelastic relaxation of a realistically stratified earth,and a further analysis of postglacial rebound[J].Geophysical Journal International,1995,120:287-311.
[23]PIERSANTI A,SPADA G,SABADINI R,et al.Global post-seismic deformation[J].Geophysical Journal International,1995,120(3):544-566.
[24]PIERSANTI A,SPADA G,SABADINI R.Global postseismic rebound of a viscoelastic earth:theory for finite faults and application to the 1964Alaska earthquake[J].Journal of Geophysical Research(Solid Earth),1997,102(B1):477-492.
[25]SABADINI R,PIERSANTI A,SPADA G.Toroidal/poloidal partitioning of global Post-seismic deformation[J].Geophysical Research Letters,1995,22(8):985-988.
[26]TANAKA Y,OKUNO J,OKUBO S.A new method for the computation of global viscoelastic post-seismic deformation in a realistic earth model(I):vertical displacement and gravity variation[J].Geophysical Journal International,2006,164(2):273-289.
[27]FU G.Surface gravity changes caused by tide-generating potential and by internal dislocation in a 3-D heterogeneous earth[D].Tokyo:University of Tokyo,2007.
[28]FU G Y,SUN W K.Surface coseismic gravity changes caused by dislocations in a 3-D heterogeneous earth[J].Geophysical Journal International,2008,172(2):479-503.
[29]杨九元,张永志,祝意青,等.尼泊尔Mw7.9地震同震及震后地表形变及重力变化模拟[J].地球物理学进展,2017,32(6):2394-2400.(YANG Jiuyuan,ZHANGYongzhi,ZHU Yiqing,et al.Simulation of co-seismic and post-seismic surface deformation and gravity changes of Nepal Mw7.9earthquake[J].Progress in Geophysics,2017,32(6):2394-2400.)
[30]张贝,程惠红,石耀霖.2015年4月25日尼泊尔Ms8.1大地震的同震效应[J].地球物理学报,2015,58(5):1794-1803.(ZHANG Bei,CHENG Huihong,SHIYaolin.Calculation of the co-seismic effect of Ms8.1earthquake,April 25,2015,Nepal[J].Chinese Journal of Geophysics,2015,58(5):1794-1803.)
[31]邓起东,程绍平,马冀,等.青藏高原地震活动特征及当前地震活动形势[J].地球物理学报,2014,57(7):2025-2042.(DENG Qidong,CHENG Shaoping,MA Ji,et al.Seismic activities and earthquake potential in the Tibetan Plateau[J].Chinese Journal of Geophysics,2014,57(7):2025-2042.)
[32]苏小宁,王振,孟国杰,等.GPS观测的2015年尼泊尔Ms8.1级地震震前应变积累及同震变形特征[J].科学通报,2015,60(22):2115-2123.(SU Xiaoning,WANG Zhen,MENG Guojie,et al.Pre-seismic strain accumulation and co-seismic deformation of the 2015Nepal Ms8.1earthquake observed by GPS[J].Chinese Science Bulletin,2015,60(22):2115-2123.)
[33]占伟,武艳强,梁洪宝,等.GPS观测结果反映的尼泊尔Mw7.8地震孕震特征[J].地球物理学报,2015,58(5):1818-1826.(ZHAN Wei,WU Yanqiang,LIANGHongbao,et al.Characteristrics of the seismogenic model for the 2015 Nepal Mw7.8earthquake derived from GPS data[J].Chinese Journal of Geophysics,2015,58(5):1818-1826.)
[34]付广裕,高尚华,张国庆,等.2015年尼泊尔Ms8.1地震的地壳重力均衡背景与地表形变响应特征[J].地球物理学报,2015,58(6):1900-1908.(FU Guangyu,GAO Shanghua,ZHANG Guoqing,et al.Gravitational isostasy background and surface deformation response characteristics of the 2015 Nepal Ms8.1earthquake[J].Chinese Journal of Geophysics,2015,58(6):1900-1908.)
[35]赵斌,杜瑞林,张锐,等.GPS测定的尼泊尔Mw7.9和Mw7.3级地震同震形变场[J].科学通报,2015,60(28/29):2758-2764.(ZHAO Bin,DU Ruilin,ZHANGRui,et al.Co-seismic displacements associated with the2015Nepal Mw7.9earthquake and Mw7.3after shock constrained by global positioning system measurements[J].Chinese Science Bulletin,2015,60(28/29):2758-2764.)
[2]BANERJEE P,POLLITZ F F,BURGMANN R.The size and duration of the Sumatra-Andaman earthquake from far-field static offsets[J].Science,2005,308(5729):1769-1772.
[3]WANG M,LI Q,WANG F,et al.Far-field coseismic displacements associated with the 2011 Tohoku-Oki earthquake in Japan observed by global positioning system[J].Chinese Science Bulletin,2011,56(23):2419-2424.
[4]ARAYA A,MORI W,HAYAKAWA H,et al.Astrain step observed by a laser strainmeter in Kamioka[J].Chikyu Monthly,Supplement,2006,56:104-110.
[5]STEKETEE J A.On Volterra’s dislocation in a semiinfinite elastic medium[J].Canadian Journal of Physics,1958,36(2):192-205.
[6]CHINNERY M A.The deformation of ground around surface faults[J].Bulletin of the Seismological Society of America,1961,51(3):355-372.
[7]CHINNERY M A.The stress changes that accompany strike-slip faulting[J].Bulletin of the Seismological Society of America,1963,53(5):921-932.
[8]MARUYAMA T.Statical elastic dislocations in an infinite and semi-infinite medium[J].Bulletin Earthquake Research Institute,University of Tokyo,1964,42:289-368.
[9]PRESS F.Displacements,strains and tilts at teleseismic distances[J].Journal of Geophysical Research,1965,70(10):2395-2412.
[10]OKADA Y.Surface deformation due to shear and tensile faults in a halfspace[J].Bulletin Seismological Society of America,1985,75(4):1135-1154.
[11]OKADA Y.Internal deformation due to shear and tensile faults in a half-space[J].Bulletin Seismological Society of America,1992,82(2):1018-1040.
[12]SATO R.Crustal deformation due to a dislocation in a multi-layered medium[J].Journal of Physical of the Earth,1971,19(1):31-46.
[13]JOVANOVICH D B,HUSSEINI M I,CHINNERY MA.Elastic dislocations in a layered half-space:I.basic theory and numerical methods[J].Geophysical Journal Royal Astronomical Society,1974,39(2):205-217.
[14]JOVANOVICH D B,HUSSEINI M I,CHINNERY MA.Elastic dislocations in a layered half-space:II.the point source[J].Geophysical Journal Royal Astronomical Society,1974,39(2):219-239.
[15]WANG R J,MARTIN F L,ROTH F.Computation of deformation induced by earthquakes in a multi-layered elastic crust:FORTRAN programs EDGRN/EDCMP[J].Computers&Geoscience,2003,29(2):195-207.
[16]WANG R J,MARTIN F L,ROTH F.PSGRN/PSCMP:a new code for calculating co-and post-seismic deformation,geoid and gravity changes based on the viscoelastic-gravitational dislocation theory[J].Computers&Geoscience,2006,32(4):527-541.
[17]BEN-MENAHEM A,SINGH S J.Eigenvector expansions of Green’s dyads with applications to geophysical theory[J].Geophysical Journal International,1968,16(4):417-452.
[18]BEN-MENAHEM A,SINGH S J,SOLOMON F.Static deformation of a spherical earth model by internal dislocations[J].Bulletin Seismological Society of America,1969,59(2):813-853.
[19]SUN W K,OKUBO S.Surface potential and gravity changes due to internal dislocations in a spherical Earth,Ⅰ.theory for a point dislocation[J].Geophysical Journal International,1993,114(3):569-592.
[20]SUN W K,OKUBO S,FU G Y,et al.General formulations of global co-seismic deformations caused by an arbitrary dislocation in a spherically symmetric earth model:applicable to deformed earth surface and spacefixed point[J].Geophysical Journal International,2009,177(3):817-833.
[21]POLLITZ F F.Postseismic relaxation theory on the spherical Earth[J].Bulletin Seismological Society of America,1992,82(1):422-453.
[22]HAN D,WAHR J.The viscoelastic relaxation of a realistically stratified earth,and a further analysis of postglacial rebound[J].Geophysical Journal International,1995,120:287-311.
[23]PIERSANTI A,SPADA G,SABADINI R,et al.Global post-seismic deformation[J].Geophysical Journal International,1995,120(3):544-566.
[24]PIERSANTI A,SPADA G,SABADINI R.Global postseismic rebound of a viscoelastic earth:theory for finite faults and application to the 1964Alaska earthquake[J].Journal of Geophysical Research(Solid Earth),1997,102(B1):477-492.
[25]SABADINI R,PIERSANTI A,SPADA G.Toroidal/poloidal partitioning of global Post-seismic deformation[J].Geophysical Research Letters,1995,22(8):985-988.
[26]TANAKA Y,OKUNO J,OKUBO S.A new method for the computation of global viscoelastic post-seismic deformation in a realistic earth model(I):vertical displacement and gravity variation[J].Geophysical Journal International,2006,164(2):273-289.
[27]FU G.Surface gravity changes caused by tide-generating potential and by internal dislocation in a 3-D heterogeneous earth[D].Tokyo:University of Tokyo,2007.
[28]FU G Y,SUN W K.Surface coseismic gravity changes caused by dislocations in a 3-D heterogeneous earth[J].Geophysical Journal International,2008,172(2):479-503.
[29]杨九元,张永志,祝意青,等.尼泊尔Mw7.9地震同震及震后地表形变及重力变化模拟[J].地球物理学进展,2017,32(6):2394-2400.(YANG Jiuyuan,ZHANGYongzhi,ZHU Yiqing,et al.Simulation of co-seismic and post-seismic surface deformation and gravity changes of Nepal Mw7.9earthquake[J].Progress in Geophysics,2017,32(6):2394-2400.)
[30]张贝,程惠红,石耀霖.2015年4月25日尼泊尔Ms8.1大地震的同震效应[J].地球物理学报,2015,58(5):1794-1803.(ZHANG Bei,CHENG Huihong,SHIYaolin.Calculation of the co-seismic effect of Ms8.1earthquake,April 25,2015,Nepal[J].Chinese Journal of Geophysics,2015,58(5):1794-1803.)
[31]邓起东,程绍平,马冀,等.青藏高原地震活动特征及当前地震活动形势[J].地球物理学报,2014,57(7):2025-2042.(DENG Qidong,CHENG Shaoping,MA Ji,et al.Seismic activities and earthquake potential in the Tibetan Plateau[J].Chinese Journal of Geophysics,2014,57(7):2025-2042.)
[32]苏小宁,王振,孟国杰,等.GPS观测的2015年尼泊尔Ms8.1级地震震前应变积累及同震变形特征[J].科学通报,2015,60(22):2115-2123.(SU Xiaoning,WANG Zhen,MENG Guojie,et al.Pre-seismic strain accumulation and co-seismic deformation of the 2015Nepal Ms8.1earthquake observed by GPS[J].Chinese Science Bulletin,2015,60(22):2115-2123.)
[33]占伟,武艳强,梁洪宝,等.GPS观测结果反映的尼泊尔Mw7.8地震孕震特征[J].地球物理学报,2015,58(5):1818-1826.(ZHAN Wei,WU Yanqiang,LIANGHongbao,et al.Characteristrics of the seismogenic model for the 2015 Nepal Mw7.8earthquake derived from GPS data[J].Chinese Journal of Geophysics,2015,58(5):1818-1826.)
[34]付广裕,高尚华,张国庆,等.2015年尼泊尔Ms8.1地震的地壳重力均衡背景与地表形变响应特征[J].地球物理学报,2015,58(6):1900-1908.(FU Guangyu,GAO Shanghua,ZHANG Guoqing,et al.Gravitational isostasy background and surface deformation response characteristics of the 2015 Nepal Ms8.1earthquake[J].Chinese Journal of Geophysics,2015,58(6):1900-1908.)
[35]赵斌,杜瑞林,张锐,等.GPS测定的尼泊尔Mw7.9和Mw7.3级地震同震形变场[J].科学通报,2015,60(28/29):2758-2764.(ZHAO Bin,DU Ruilin,ZHANGRui,et al.Co-seismic displacements associated with the2015Nepal Mw7.9earthquake and Mw7.3after shock constrained by global positioning system measurements[J].Chinese Science Bulletin,2015,60(28/29):2758-2764.)