2017年米林6.9级地震震源区速度结构与余震重定位
|
摘要
利用西藏自治区林芝地区的固定地震台站与南迦巴瓦流动测震台站在2017年11月18日至2017年11月24日记录到的430个余震的直达波走时数据反演得到了震源区的三维P波速度、S波速度结构,并利用三维速度结构对余震进行了重定位.成像结果显示,米林地震震源区在0～5km深度内存在低地震波速度异常;在5～15km深度内,存在高地震波速度异常,该高速异常致使震源区西南侧的地震波速度高于东北侧.重定位结果中,余震呈条带状以NW-SE走向展布,震源深度具有西南方向深、东北方向浅的特征.主震位于11km深度处、高地震波速异常体顶部,余震主要分布在高地震波速度与低地震波速度过渡的区域.对成像结果的分析表明,震源区浅部的低速异常具有低泊松比的特性,与富石英的沉积变质杂岩体-东久杂岩单元的岩性特征有关;深部的速度结构特征则可能反映了发震断层上盘地震波速度高,下盘地震波速度低的介质特性.余震重定位结果与成像结果联合表明:此次地震发震断层从11km深度处,东久杂岩体下方的高地震波速度异常顶部开始破裂,继而在5～15km深度内发生后续破裂,后续破裂的发生区域正处于喜马拉雅构造单元与冈底斯构造单元接触的形变区内.此外,根据地震波速度计算的泊松比反映了震源区持续的低泊松比特征,暗示此次地震与流体活动并无直接关系.
This work imaged the P-wave and S-wave velocity structures in the source region of2017 Mainling,Tibet earthquake by inverting arrival times of 430 aftershocks observed at seismic stations in the Linzhi area and temporary stations around Namche Barwa during November 18 thto24 th,2017.Then the aftershocks are relocated using these 3 Dvelocity structures.Results show low-velocity and high-velocity anomalies at depths 0～5 km depths and 5～15 km,respectively.The latter makes the seismic velocity in the southwest is higher than that in the northeast of the source.The relocated aftershocks are distributed in NW-SE direction,deeper in the southwest and shallower in the northeast.The main shock is at depth 11 km,the top of a high-velocityanomaly body,while the aftershocks are located in a transition zone between high-and lowvelocity anomalies.Analysis suggests that the initial rupture of this event started from the top of a high-velocity area below the Dongjiu complex at depth of 11 km,and subsequently the rupture continued in a dramatically deformed area caused by Himalayan unit and Gandisêunit at 5～15 km depths.Additionally,there is no fluid activity involved as implied by the persistent low-Poisson′s ratio derived from calculation of seismic velocities.
This work imaged the P-wave and S-wave velocity structures in the source region of2017 Mainling,Tibet earthquake by inverting arrival times of 430 aftershocks observed at seismic stations in the Linzhi area and temporary stations around Namche Barwa during November 18 thto24 th,2017.Then the aftershocks are relocated using these 3 Dvelocity structures.Results show low-velocity and high-velocity anomalies at depths 0～5 km depths and 5～15 km,respectively.The latter makes the seismic velocity in the southwest is higher than that in the northeast of the source.The relocated aftershocks are distributed in NW-SE direction,deeper in the southwest and shallower in the northeast.The main shock is at depth 11 km,the top of a high-velocityanomaly body,while the aftershocks are located in a transition zone between high-and lowvelocity anomalies.Analysis suggests that the initial rupture of this event started from the top of a high-velocity area below the Dongjiu complex at depth of 11 km,and subsequently the rupture continued in a dramatically deformed area caused by Himalayan unit and Gandisêunit at 5～15 km depths.Additionally,there is no fluid activity involved as implied by the persistent low-Poisson′s ratio derived from calculation of seismic velocities.
引文
Aki K,Christoffersson A,Husebye E S.1977.Determination of the three-dimensional seismic structure of the lithosphere.Journal of Geophysical Research,82(2):277-296.
Bai L,Li G H,Song B W.2017.The source parameters of the M6.9Mainling,Tibet earthquake and its tectonic implications.Chinese Journal of Geophysics(in Chinese),60(12):4956-4963,doi:10.6038/cjg20171234.
Carmichael R S.1982.Handbook of Physical Properties of Rocks.Boca Raton:CRC Press,Inc.
Chang L J,Wang C Y,Ding Z F,et al.2015.Upper mantle anisotropy of the eastern Himalayan syntaxis and surrounding regions from shear wave splitting analysis.Science China Earth Sciences,58(10):1872-1882.
Cheng C,Bai L,Lin D,et al.2017.Crustal structure of Eastern Himalayan Syntaxis revealed by receiver function method.Chinese Journal of Geophysics(in Chinese),60(8):2969-2979,doi:10.6038/cjg20170806.
Cui Z X,Pei S P.2009.Study on Pn velocity and anisotropy in the uppermost mantle of the Eastern Himalayan Syntaxis and surrounding regions.Chinese Journal of Geophysics(in Chinese),52(9):2245-2254,doi:10.3969/j.issn.0001-5733.2009.09.008.
Eberhart-Phillips D.1995.Examination of seismicity in the central Alpine fault region,South Island,New Zealand.New Zealand Journal of Geology and Geophysics,38(4):571-578.
Ellsworth W L,Koyanagi R Y.1977.Three-dimensional crust and mantle structure of Kilauea Volcano,Hawaii.Journal of Geophysical Research,82(33):5379-5394.
Evans J R,Achauer U.1993.Using the ACH method:theory and application to continental-scale studies.∥Iyer H M,Hirahara K eds.Seismic Tomography-Theory and Practice.London:Chapman and Hall,319-360.
Franklin J N.1970.Well-posed stochastic extensions of ill-posed linear problems.Journal of Mathematical Analysis and Applications,31(3):682-716.
Fu Y V,Li A B,Chen Y J.2010.Crustal and upper mantle structure of southeast Tibet from Rayleigh wave tomography.Journal of Geophysical Research:Solid Earth,115(B12):B12323,doi:10.1029/2009JB007160.
Goodway B,Chen T,Downton J.1997.Improved AVO fluid detection and lithology discrimination using Lamépetrophysical parameters;“λρ”,“μρ”and“λ/μfluid stack”,from P and Sinversions.∥67th Ann.Internat Mtg.,Soc.Expi.Geophys..Expanded Abstracts,22:183-186.
Goodway B.2001.AVO and Laméconstants for rock parameterization and fluid detection.CSEG Recorder,26(6):39-60.
Ji S C,Wang Q,Wang Q,et al.2007.Correlation between elastic properties and density for Sulu-Dabie UHP metamorphic rocks.Acta Petrologica Sinica,23(12):3054-3064.
Ji S C,Wang Q,Yang W C.2009.Correlation between crustal thickness and Poisson′s ratio in the North China craton and its implication for lithospheric thinning.Acta Geologica Sinica,83(3):324-330.
Kissling E.1988.Geotomography with local earthquake data.Reviews of Geophysics,26(4):659-698.
Kissling E,Ellsworth W L,Eberhart-Phillips D,et al.1994.Initial reference models in local earthquake tomography.Journal of Geophysical Research:Solid Earth,99(B10):19635-19646.
Kissling E,Kradolfer U,Maurer H.1995.Program Velest User′s Guide,Institute of Geophysics,ETH Zuerich.
Laske G,Masters G,Ma Z,et al.2013.Update on CRUST1.0-A1-degree Global Model of Earth′s Crust.∥EGU General Assembly2013.15:EGU2013-2658.
Lin C H,Peng M,Tan H D,et al.2017.Crustal structure beneath Namche Barwa,eastern Himalayan syntaxis:New insights from three-dimensional magnetotelluric imaging.Journal of Geophysical Research:Solid Earth,122(7):5082-5100.
Liu Y,Siebel W,Wang M.2006.Intracontinental deformed processes of the eastern Himalayan Syntaxis.Acta Geologica Sinica(in Chinese),80(9):1274-1284.
Mooney W D,Ginzburg A.1986.Seismic measurements of the internal properties of fault zones.Pure and Applied Geophysics,124(1-2):141-157.
Ren Y,Shen Y.2008.Finite frequency tomography in southeastern Tibet:Evidence for the causal relationship between mantle lithosphere delamination and the north-south trending.Journal of Geophysical Research:Solid Earth,113(B10):B10316,doi:10.1029/2008JB005615.
Roecker S W.1982.Velocity structure of the Pamir-Hindu Kush Region:Possible evidence of subducted crust.Journal of Geophysical Research:Solid earth,87(B2):945-959.
Takei Y.2002.Effect of pore geometry on VP/VS:From equilibrium geometry to crack.Journal of Geophysical Research:Solid Earth,107(B2):2043,doi:10.1029/2001JB000522.
Thurber C H.1983.Earthquake locations and three-dimensional crustal structure in the Coyote Lake Area,central California.Journal of Geophysical Research:Solid Earth,88(B10):8226-8236.
Thurber C H.1992.Hypocenter-velocity structure coupling in local earthquake tomography.Physics of the Earth and Planetary Interiors,75(1-3):55-62.
Thurber C H,Roecker S,Ellsworth W,et al.1997.Two-dimensional seismic image of the San Andreas Fault in the Northern Gabilan Range,central California:Evidence for fluids in the fault zone.Geophysical Research Letters,24(13):1591-1594.
Wessel P,Smith W H F.1998.New,improved version of Generic Mapping Tools released.Eos,Transactions American Geophysical Union,79(47):579-579.
Xu Q,Zhao J M,Pei S P,et al.2013.Imaging lithospheric structure of the eastern Himalayan syntaxis:New insights from receiver function analysis.Journal of Geophysical Research:Solid Earth,118(5):2323-2332.
Xu W W,Zheng Y T.2005.Distribution of Poisson′s ratios in the northwestern basin-mountain boundary of the Bohai Bay Basin.Chinese Journal of Geophysics(in Chinese),48(5):1077-1084.
Xu Z Q,Cai Z H,Zhang Z M,et al.2008.Tectonics and fabric kinematics of the Namche Barwa terrane,Eastern Himalayan Syntaxis.Acta Petrologica Sinica,24(7):1463-1476.
Yang W C,Qu C,Yu C Q.2011.Crustal Poisson′s ratio anomalies in the eastern part of North China and their origins.Geoscience Frontiers,2(3):313-321.
Zhao D P,Kanamori H,Negishi H,et al.1996.Tomography of the source area of the 1995Kobe earthquake:evidence for fluids at the hypocenter?.Science,274(5294):1891-1894.
白玲,李国辉,宋博文.2017.2017年西藏米林6.9级地震震源参数及其构造意义.地球物理学报,60(12):4956-4963,doi:10.6038/cjg20171234.
常利军,王椿镛,丁志峰等.2015.喜马拉雅东构造结及周边地区上地幔各向异性.中国科学:地球科学,2015,45(5):577-588.
程成,白玲,丁林等.2017.利用接收函数方法研究喜马拉雅东构造结地区地壳结构.地球物理学报,60(8):2969-2979,doi:10.6038/cjg20170806.
崔仲雄,裴顺平.2009.青藏高原东构造结及周边地区上地幔顶部Pn速度结构和各向异性研究.地球物理学报,52(9):2245-2254,doi:10.3969/j.issn.0001-5733.2009.09.008.
嵇少丞,王茜,王勤等.2007.苏鲁-大别超高压变质岩的弹性力学性质与密度的关系.岩石学报,23(12):3054-3064.
嵇少丞,王茜,杨文采.2009.华北克拉通泊松比与地壳厚度的关系及其大地构造意义.地质学报,83(3):324-330.
刘焰,Siebel W,王猛.2006.东喜马拉雅构造结陆内变形过程的研究.地质学报,80(9):1274-1284.
许卫卫,郑天愉.2005.渤海湾盆地北西盆山边界地区泊松比分布.地球物理学报,48(5):1077-1084.
许志琴,蔡志慧,张泽明等.2008.喜马拉雅东构造结---南迦巴瓦构造及组构运动学.岩石学报,24(7):1463-1476.
Bai L,Li G H,Song B W.2017.The source parameters of the M6.9Mainling,Tibet earthquake and its tectonic implications.Chinese Journal of Geophysics(in Chinese),60(12):4956-4963,doi:10.6038/cjg20171234.
Carmichael R S.1982.Handbook of Physical Properties of Rocks.Boca Raton:CRC Press,Inc.
Chang L J,Wang C Y,Ding Z F,et al.2015.Upper mantle anisotropy of the eastern Himalayan syntaxis and surrounding regions from shear wave splitting analysis.Science China Earth Sciences,58(10):1872-1882.
Cheng C,Bai L,Lin D,et al.2017.Crustal structure of Eastern Himalayan Syntaxis revealed by receiver function method.Chinese Journal of Geophysics(in Chinese),60(8):2969-2979,doi:10.6038/cjg20170806.
Cui Z X,Pei S P.2009.Study on Pn velocity and anisotropy in the uppermost mantle of the Eastern Himalayan Syntaxis and surrounding regions.Chinese Journal of Geophysics(in Chinese),52(9):2245-2254,doi:10.3969/j.issn.0001-5733.2009.09.008.
Eberhart-Phillips D.1995.Examination of seismicity in the central Alpine fault region,South Island,New Zealand.New Zealand Journal of Geology and Geophysics,38(4):571-578.
Ellsworth W L,Koyanagi R Y.1977.Three-dimensional crust and mantle structure of Kilauea Volcano,Hawaii.Journal of Geophysical Research,82(33):5379-5394.
Evans J R,Achauer U.1993.Using the ACH method:theory and application to continental-scale studies.∥Iyer H M,Hirahara K eds.Seismic Tomography-Theory and Practice.London:Chapman and Hall,319-360.
Franklin J N.1970.Well-posed stochastic extensions of ill-posed linear problems.Journal of Mathematical Analysis and Applications,31(3):682-716.
Fu Y V,Li A B,Chen Y J.2010.Crustal and upper mantle structure of southeast Tibet from Rayleigh wave tomography.Journal of Geophysical Research:Solid Earth,115(B12):B12323,doi:10.1029/2009JB007160.
Goodway B,Chen T,Downton J.1997.Improved AVO fluid detection and lithology discrimination using Lamépetrophysical parameters;“λρ”,“μρ”and“λ/μfluid stack”,from P and Sinversions.∥67th Ann.Internat Mtg.,Soc.Expi.Geophys..Expanded Abstracts,22:183-186.
Goodway B.2001.AVO and Laméconstants for rock parameterization and fluid detection.CSEG Recorder,26(6):39-60.
Ji S C,Wang Q,Wang Q,et al.2007.Correlation between elastic properties and density for Sulu-Dabie UHP metamorphic rocks.Acta Petrologica Sinica,23(12):3054-3064.
Ji S C,Wang Q,Yang W C.2009.Correlation between crustal thickness and Poisson′s ratio in the North China craton and its implication for lithospheric thinning.Acta Geologica Sinica,83(3):324-330.
Kissling E.1988.Geotomography with local earthquake data.Reviews of Geophysics,26(4):659-698.
Kissling E,Ellsworth W L,Eberhart-Phillips D,et al.1994.Initial reference models in local earthquake tomography.Journal of Geophysical Research:Solid Earth,99(B10):19635-19646.
Kissling E,Kradolfer U,Maurer H.1995.Program Velest User′s Guide,Institute of Geophysics,ETH Zuerich.
Laske G,Masters G,Ma Z,et al.2013.Update on CRUST1.0-A1-degree Global Model of Earth′s Crust.∥EGU General Assembly2013.15:EGU2013-2658.
Lin C H,Peng M,Tan H D,et al.2017.Crustal structure beneath Namche Barwa,eastern Himalayan syntaxis:New insights from three-dimensional magnetotelluric imaging.Journal of Geophysical Research:Solid Earth,122(7):5082-5100.
Liu Y,Siebel W,Wang M.2006.Intracontinental deformed processes of the eastern Himalayan Syntaxis.Acta Geologica Sinica(in Chinese),80(9):1274-1284.
Mooney W D,Ginzburg A.1986.Seismic measurements of the internal properties of fault zones.Pure and Applied Geophysics,124(1-2):141-157.
Ren Y,Shen Y.2008.Finite frequency tomography in southeastern Tibet:Evidence for the causal relationship between mantle lithosphere delamination and the north-south trending.Journal of Geophysical Research:Solid Earth,113(B10):B10316,doi:10.1029/2008JB005615.
Roecker S W.1982.Velocity structure of the Pamir-Hindu Kush Region:Possible evidence of subducted crust.Journal of Geophysical Research:Solid earth,87(B2):945-959.
Takei Y.2002.Effect of pore geometry on VP/VS:From equilibrium geometry to crack.Journal of Geophysical Research:Solid Earth,107(B2):2043,doi:10.1029/2001JB000522.
Thurber C H.1983.Earthquake locations and three-dimensional crustal structure in the Coyote Lake Area,central California.Journal of Geophysical Research:Solid Earth,88(B10):8226-8236.
Thurber C H.1992.Hypocenter-velocity structure coupling in local earthquake tomography.Physics of the Earth and Planetary Interiors,75(1-3):55-62.
Thurber C H,Roecker S,Ellsworth W,et al.1997.Two-dimensional seismic image of the San Andreas Fault in the Northern Gabilan Range,central California:Evidence for fluids in the fault zone.Geophysical Research Letters,24(13):1591-1594.
Wessel P,Smith W H F.1998.New,improved version of Generic Mapping Tools released.Eos,Transactions American Geophysical Union,79(47):579-579.
Xu Q,Zhao J M,Pei S P,et al.2013.Imaging lithospheric structure of the eastern Himalayan syntaxis:New insights from receiver function analysis.Journal of Geophysical Research:Solid Earth,118(5):2323-2332.
Xu W W,Zheng Y T.2005.Distribution of Poisson′s ratios in the northwestern basin-mountain boundary of the Bohai Bay Basin.Chinese Journal of Geophysics(in Chinese),48(5):1077-1084.
Xu Z Q,Cai Z H,Zhang Z M,et al.2008.Tectonics and fabric kinematics of the Namche Barwa terrane,Eastern Himalayan Syntaxis.Acta Petrologica Sinica,24(7):1463-1476.
Yang W C,Qu C,Yu C Q.2011.Crustal Poisson′s ratio anomalies in the eastern part of North China and their origins.Geoscience Frontiers,2(3):313-321.
Zhao D P,Kanamori H,Negishi H,et al.1996.Tomography of the source area of the 1995Kobe earthquake:evidence for fluids at the hypocenter?.Science,274(5294):1891-1894.
白玲,李国辉,宋博文.2017.2017年西藏米林6.9级地震震源参数及其构造意义.地球物理学报,60(12):4956-4963,doi:10.6038/cjg20171234.
常利军,王椿镛,丁志峰等.2015.喜马拉雅东构造结及周边地区上地幔各向异性.中国科学:地球科学,2015,45(5):577-588.
程成,白玲,丁林等.2017.利用接收函数方法研究喜马拉雅东构造结地区地壳结构.地球物理学报,60(8):2969-2979,doi:10.6038/cjg20170806.
崔仲雄,裴顺平.2009.青藏高原东构造结及周边地区上地幔顶部Pn速度结构和各向异性研究.地球物理学报,52(9):2245-2254,doi:10.3969/j.issn.0001-5733.2009.09.008.
嵇少丞,王茜,王勤等.2007.苏鲁-大别超高压变质岩的弹性力学性质与密度的关系.岩石学报,23(12):3054-3064.
嵇少丞,王茜,杨文采.2009.华北克拉通泊松比与地壳厚度的关系及其大地构造意义.地质学报,83(3):324-330.
刘焰,Siebel W,王猛.2006.东喜马拉雅构造结陆内变形过程的研究.地质学报,80(9):1274-1284.
许卫卫,郑天愉.2005.渤海湾盆地北西盆山边界地区泊松比分布.地球物理学报,48(5):1077-1084.
许志琴,蔡志慧,张泽明等.2008.喜马拉雅东构造结---南迦巴瓦构造及组构运动学.岩石学报,24(7):1463-1476.
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |