基于地壳介质各向异性分析青藏高原东北缘构造应力特征
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摘要
青藏高原东北缘由于受到多个构造块体的共同约束,表现出复杂的地球物理特性和地质特性,本文利用甘肃数字地震台网(2001—2008年)的观测资料,采用系统分析方法(SAM),进行地壳剪切波分裂分析,获得研究区内18个台站共1005条记录的剪切波分裂参数.研究结果表明,青藏高原东北缘介质各向异性在空间上存在差异,慢剪切波延迟时间表明了地壳介质各向异性的强弱变化特征,快剪切波平均偏振方向则反映了本区区域构造应力的空间变化特征.分析认为,祁连山—河西走廊活动构造区直接受青藏地块与阿拉善地块间相互作用,与青藏地块构造应力一致;甘东南活动构造区的应力环境主要受到内部活动断裂的共同作用,具有局部构造应力的特征.
The northeastern margin of Tibetan plateau is controlled jointly by several tectonic blocks and shows complicated geophysical and geological characters.In the paper,the data from Gansu Seismological Network(2001—2008) are analyzed with the seismic anisotropy analysis method in crust(SAM).1005 shear-wave splitting parameters from 18 stations are obtained.The results show that the crustal seismic anisotropy in the northeastern margin of Tibetan plateau varies in space.The delay times of slow shear-waves show the variation characteristics of the strength of crustal seismic anisotropy and the average polarizations of fast shear-waves reflect the spacial variation characteristics of regional tectonic stress.It is shown that the interaction of Tibetan plateau block and Alxa block controls the region of Qilianshan-Hexi corridor active structures,where the direction of tectonic stress is the same as in Tibetan plateau block.In the southeast of Gansu active structure region,it is regarded that active faults are influential on the stress field,which shows local tectonic stress characteristics.
The northeastern margin of Tibetan plateau is controlled jointly by several tectonic blocks and shows complicated geophysical and geological characters.In the paper,the data from Gansu Seismological Network(2001—2008) are analyzed with the seismic anisotropy analysis method in crust(SAM).1005 shear-wave splitting parameters from 18 stations are obtained.The results show that the crustal seismic anisotropy in the northeastern margin of Tibetan plateau varies in space.The delay times of slow shear-waves show the variation characteristics of the strength of crustal seismic anisotropy and the average polarizations of fast shear-waves reflect the spacial variation characteristics of regional tectonic stress.It is shown that the interaction of Tibetan plateau block and Alxa block controls the region of Qilianshan-Hexi corridor active structures,where the direction of tectonic stress is the same as in Tibetan plateau block.In the southeast of Gansu active structure region,it is regarded that active faults are influential on the stress field,which shows local tectonic stress characteristics.
引文
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[11]Zhang Z J,Teng J W,Badal J,et al.Construction of regional and local seismic anisotropic structures from wide-angle seismic data:crustal deformation in the southeast of China.Journal of Seismology,2009,13(2):241-252.
[12]Gao Y,Crampin S.Observations of stress relaxation before earthquakes.Geophys.J.Int.,2004,157(2):578-582.
[13]高原,梁维,丁香等.云南2001年施甸地震的剪切波分裂参数变化特征.地震学报,2004,26(6):576-582.Gao Y,Liang W,Ding X,et al.Variational characteristics of shear-wave splitting on the2001Shidian earthquakes in Yunnan,China.Acta Seismologica Sinica(in Chinese),2004,26(6):576-582.
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[15]丁志峰,武岩,王辉等.2008年汶川地震震源区横波分裂的变化特征.中国科学(D辑):地球科学,2008,38(12):1600-1604.Ding Z F,Wu Y,Wang H,et al.Variations of shear wave splitting in the2008Wenchuan earthquake region.Science in China(Series D):Series D:Earth Sciences,2008,51(12):1712-1716.
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[17]高原,郑斯华,周蕙兰.唐山地区快剪切波偏振图像及其变化.地球物理学报,1999,42(2):228-232.Gao Y,Zheng S H,Zhou H L.Polarization patterns of fast shear wave in Tangshan region and their variations.Chinese J.Geophys.(in Chinese),1999,42(2):228-232.
[18]Crampin S,Volti T,Chastin S,et al.Indication of high pore-fluid pressures in a seismically-active fault zone.Geophys.J.Int.,2002,151(2):F1-F5.
[19]吴晶,高原,蔡晋安等.华夏地块东南部地壳地震各向异性特征初步研究.地球物理学报,2007,50(6):1748-1756.Wu J,Gao Y,Cai J A,et al.Preliminary study on seismic anisotropy in the crust in southeast of Cathaysia Block.Chinese J.Geophys.(in Chinese),2007,50(6):1748-1756.
[20]高原,吴晶.利用剪切波各向异性推断地壳主压应力场—以首都圈地区为例.科学通报,2008,53(23):2933-2939.Gao Y,Wu J.Compressive stress field in the crust deduced from shear-wave anisotropy:an example in capital area of China.Chinese Science Bulletin,2008,53(18):2840-2848.
[21]吴晶,高原,石玉涛等.基于地壳介质各向异性分析江苏及邻区构造应力特征.地球物理学报,2010,53(7):1622-1630.Wu J,Gao Y,Shi Y T,et al.Tectonic stress analysis based on the crustal seismic anisotropy in Jiangsu and its adjacent area.Chinese J.Geophys.(in Chinese),2010,53(7):1622-1630.
[22]石玉涛,高原,赵翠萍等.汶川地震余震序列的地震各向异性.地球物理学报,2009,52(2):398-407.Shi Y T,Gao Y,Zhao C P,et al.A study of seismic anisotropy of Wenchuan earthquake sequence.Chinese J.Geophys.(in Chinese),2009,52(2):398-407.
[23]高原,郑斯华.唐山地区剪切波分裂研究(Ⅱ)—相关函数分析法.中国地震,1994,10(增刊):11-21.Gao Y,Zheng S H.On shear-wave splitting in Tangshan region(Ⅱ)—correlation function analysis method.Earthquake Research in China(in Chinese),1994,10(Suppl.):11-21.
[24]高原,石玉涛,梁维等.剪切波分裂分析系统SAM(2007)—软件系统.中国地震,2008,24(4):345-353.Gao Y,Shi Y T,Liang W,et al.Systematic analysis method of shear-wave splitting SAM(2007):software system.Earthquake Research in China(in Chinese),2008,24(4):345-353.
[25]石玉涛,高原,吴晶等.剪切波分裂分析系统SAM(2007)—区域地震台网资料应用实例.中国地震,2008,24(4):354-361.Shi Y T,Gao Y,Wu J,et al.Systematic analysis method of shear-wave splitting SAM(2007):examples of application in the regional seismograph networks.Earthquake Research in China(in Chinese),2008,24(4):354-361.
[26]Crampin S,Gao Y.A review of techniques for measuring shear-wave splitting above small earthquakes.Phys.Earth Planet.Inter.,2006,159(1-2):1-14.
[27]张培震.中国大陆岩石圈最新构造变动与地震灾害.第四纪研究,1999,(5):404-413.Zhang P Z.Late Quaternary tectonic deformation and earthquake hazard in continental China.Quaternary Research,1999,(5):404-413.
[28]张培震,邓启东,张国民等.中国大陆的强震活动与活动地块.中国科学(D辑),2003,33(增刊):12-20.Zhang P Z,Deng Q D,Zhang G M,et al.Active tectonic blocks and strong earthquakes.Science in China(Series D)(in Chinese),2003,33(Suppl.):12-20.
[29]邓启东,张培震,冉勇康等.中国活动构造基本特征.中国科学(D辑),2002,32(12):1020-1030.Deng Q D,Zhang P Z,Ran Z K,et al.Characteristics of active tectonics of China.Science in China(Series D)(in Chinese),2002,32(12):1020-1030.
[30]袁道阳,何文贵,刘小凤等.10余年来甘肃省中强地震的发震构造特征.西北地震学报,2006,28(3):235-241.Yuan D Y,He W G,Liu X F,et al.The characteristics of seismogenic structure of middle-strong earthquakes in recent 10years,Gansu Province.Northwestern Seismological Journal(in Chinese),2006,28(3):235-241.
[31]徐纪人,赵志新,石川有三.中国大陆地壳应力场与构造运动区域特征研究.地球物理学报,2008,51(3):770-781.Xu J R,Zhao Z X,Ishikawa Yuzo.Regional characteristics of crustal stress field and tectonic motions in and around Chinese mainland.Chinese J.Geophys.(in Chinese),2008,51(3):770-781.
[32]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.
[33]Wang Q,Zhang P Z,Freymueller J T,et al.Present-day crustal deformation in China constrained by Global Positioning System measurements.Science,2001,294(5542):574-577.
[34]张国民,马宏生,王辉等.中国大陆活动地块与强震活动关系.中国科学D辑:地球科学,2004,34(7):591-599.Zhang G M,Ma H S,Wang H,et al.Active tectonic blocks on the Chinese mainland and its relationwith strong earthquakes.Science in China(Series D)(in Chinese),2004,34(7):591-599.
[35]虢顺民,江在森,张崇立.青藏高原东北缘晚第四纪块体划分与运动态势研究.地震地质,2000,22(3):219-231.Guo S M,Jiang Z S,Zhang C L.Division and motion status of blocks for the northeastern Tibetan Plateau in LateQuaternary.Seismology and Geology(in Chinese),2000,22(3):219-231.
[36]周民都,张元生,石雅鏐等.青藏高原东北缘地壳三维速度结构.地球物理学进展,2006,21(1):127-134.Zhou M D,Zhang Y S,Shi Y L,et al.Three-dimensional crustal velocity structure in the northeastern margin of the Qinghai-Tibetan plateau.Progress in Geophysics(in Chinese),2006,21(1):127-134.
[37]王萍,王增光.阿拉善活动块体的划分及归宿.地震,1997,17(1):103-112.Wang P,Wang Z G.Division of the Alxa Block and its attribution.Earthquake(in Chinese),1997,17(1):103-112.
[38]吴晶,高原,陈运泰等.首都圈西北部地区地壳介质地震各向异性特征初步研究.地球物理学报,2007,50(1):209-220.Wu J,Gao Y,Chen Y T,et al.Seismic anisotropy in the crust in northwestern capital area of China.Chinese J.Geophys.(in Chinese),2007,50(1):209-220.
[2]Crampin S.Seismic-wave propagation through a cracked solid:polarization as a possible dilatancy diagnostic.Geophys.J.R.Astr.Soc.,1978,53(3):467-496.
[3]Crampin S.A review of wave motion in anisotropic and cracked elastic-media.Wave Motion,1981,3(4):343-391.
[4]Crampin S,Booth D C.Shear-wave polarizations near the North Anatolian FaultⅡ,Interpretation in terms of crack-induced anisotropy.Geophys.J.R.Astr.Soc.,1985,83(1):75-92.
[5]姚陈,王培德,陈运泰.卢龙地区S波偏振与上地壳裂隙各向异性.地球物理学报,1992,35(3):305-315.Yao C,Wang P D,Chen Y T.Shear-wave polarization and crack induced anisotropy of upper crust in Lulong,north China.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1992,35(3):305-315.
[6]高原,郑斯华,王培德.海南省东方地区1992年小震群剪切波分裂研究.地球物理学报,1996,39(2):221-232.Gao Y,Zheng S H,Wang P D.Shear wave splitting study on small earthquake swarm of1992in Dongfang of Hainan,south China.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1996,39(2):221-232.
[7]Zatsepin S V,Crampin S.Modelling the compliance of crustal rock—Ⅰ:Response of shear-wave splitting to differential stress.Geophys.J.Int.,1997,129(3):477-494.
[8]Crampin S,Zatsepin S V.Modelling the compliance of crustal rock—Ⅱ:Response to temporal changes before earthquakes.Geophys.J.Int.,1997,129(3):495-506.
[9]Crampin S,Volti T,Stefánsson R.A successfully stress-forecast earthquake.Geophys.J.Int.,1999,138(1):F1-F5.
[10]Crampin S,Peacock S.A review of shear-wave splitting in the compliant crack-critical anisotropic Earth.Wave Motion,2005,41(1):59-77.
[11]Zhang Z J,Teng J W,Badal J,et al.Construction of regional and local seismic anisotropic structures from wide-angle seismic data:crustal deformation in the southeast of China.Journal of Seismology,2009,13(2):241-252.
[12]Gao Y,Crampin S.Observations of stress relaxation before earthquakes.Geophys.J.Int.,2004,157(2):578-582.
[13]高原,梁维,丁香等.云南2001年施甸地震的剪切波分裂参数变化特征.地震学报,2004,26(6):576-582.Gao Y,Liang W,Ding X,et al.Variational characteristics of shear-wave splitting on the2001Shidian earthquakes in Yunnan,China.Acta Seismologica Sinica(in Chinese),2004,26(6):576-582.
[14]Wu J,Crampin S,Gao Y,et al.Smaller source earthquakes and improved measuring techniques allow the largest earthquakes in Iceland to be stress forecast(with hindsight).Geophys.J.Int.,2006,166(3):1293～1298,doi:10.1111/j.1365-246X.2006.03054.x.
[15]丁志峰,武岩,王辉等.2008年汶川地震震源区横波分裂的变化特征.中国科学(D辑):地球科学,2008,38(12):1600-1604.Ding Z F,Wu Y,Wang H,et al.Variations of shear wave splitting in the2008Wenchuan earthquake region.Science in China(Series D):Series D:Earth Sciences,2008,51(12):1712-1716.
[16]高原,郑斯华,孙勇.唐山地区地壳裂隙各向异性.地震学报,1995,17(3):283-293.Gao Y,Zheng S H,Sun Y.Crack-induced anisotropy in the crust from shear wave splitting observed in Tangshan region,North China.Acta Seismologica Sinica(in Chinese),1995,8(3):351-363.
[17]高原,郑斯华,周蕙兰.唐山地区快剪切波偏振图像及其变化.地球物理学报,1999,42(2):228-232.Gao Y,Zheng S H,Zhou H L.Polarization patterns of fast shear wave in Tangshan region and their variations.Chinese J.Geophys.(in Chinese),1999,42(2):228-232.
[18]Crampin S,Volti T,Chastin S,et al.Indication of high pore-fluid pressures in a seismically-active fault zone.Geophys.J.Int.,2002,151(2):F1-F5.
[19]吴晶,高原,蔡晋安等.华夏地块东南部地壳地震各向异性特征初步研究.地球物理学报,2007,50(6):1748-1756.Wu J,Gao Y,Cai J A,et al.Preliminary study on seismic anisotropy in the crust in southeast of Cathaysia Block.Chinese J.Geophys.(in Chinese),2007,50(6):1748-1756.
[20]高原,吴晶.利用剪切波各向异性推断地壳主压应力场—以首都圈地区为例.科学通报,2008,53(23):2933-2939.Gao Y,Wu J.Compressive stress field in the crust deduced from shear-wave anisotropy:an example in capital area of China.Chinese Science Bulletin,2008,53(18):2840-2848.
[21]吴晶,高原,石玉涛等.基于地壳介质各向异性分析江苏及邻区构造应力特征.地球物理学报,2010,53(7):1622-1630.Wu J,Gao Y,Shi Y T,et al.Tectonic stress analysis based on the crustal seismic anisotropy in Jiangsu and its adjacent area.Chinese J.Geophys.(in Chinese),2010,53(7):1622-1630.
[22]石玉涛,高原,赵翠萍等.汶川地震余震序列的地震各向异性.地球物理学报,2009,52(2):398-407.Shi Y T,Gao Y,Zhao C P,et al.A study of seismic anisotropy of Wenchuan earthquake sequence.Chinese J.Geophys.(in Chinese),2009,52(2):398-407.
[23]高原,郑斯华.唐山地区剪切波分裂研究(Ⅱ)—相关函数分析法.中国地震,1994,10(增刊):11-21.Gao Y,Zheng S H.On shear-wave splitting in Tangshan region(Ⅱ)—correlation function analysis method.Earthquake Research in China(in Chinese),1994,10(Suppl.):11-21.
[24]高原,石玉涛,梁维等.剪切波分裂分析系统SAM(2007)—软件系统.中国地震,2008,24(4):345-353.Gao Y,Shi Y T,Liang W,et al.Systematic analysis method of shear-wave splitting SAM(2007):software system.Earthquake Research in China(in Chinese),2008,24(4):345-353.
[25]石玉涛,高原,吴晶等.剪切波分裂分析系统SAM(2007)—区域地震台网资料应用实例.中国地震,2008,24(4):354-361.Shi Y T,Gao Y,Wu J,et al.Systematic analysis method of shear-wave splitting SAM(2007):examples of application in the regional seismograph networks.Earthquake Research in China(in Chinese),2008,24(4):354-361.
[26]Crampin S,Gao Y.A review of techniques for measuring shear-wave splitting above small earthquakes.Phys.Earth Planet.Inter.,2006,159(1-2):1-14.
[27]张培震.中国大陆岩石圈最新构造变动与地震灾害.第四纪研究,1999,(5):404-413.Zhang P Z.Late Quaternary tectonic deformation and earthquake hazard in continental China.Quaternary Research,1999,(5):404-413.
[28]张培震,邓启东,张国民等.中国大陆的强震活动与活动地块.中国科学(D辑),2003,33(增刊):12-20.Zhang P Z,Deng Q D,Zhang G M,et al.Active tectonic blocks and strong earthquakes.Science in China(Series D)(in Chinese),2003,33(Suppl.):12-20.
[29]邓启东,张培震,冉勇康等.中国活动构造基本特征.中国科学(D辑),2002,32(12):1020-1030.Deng Q D,Zhang P Z,Ran Z K,et al.Characteristics of active tectonics of China.Science in China(Series D)(in Chinese),2002,32(12):1020-1030.
[30]袁道阳,何文贵,刘小凤等.10余年来甘肃省中强地震的发震构造特征.西北地震学报,2006,28(3):235-241.Yuan D Y,He W G,Liu X F,et al.The characteristics of seismogenic structure of middle-strong earthquakes in recent 10years,Gansu Province.Northwestern Seismological Journal(in Chinese),2006,28(3):235-241.
[31]徐纪人,赵志新,石川有三.中国大陆地壳应力场与构造运动区域特征研究.地球物理学报,2008,51(3):770-781.Xu J R,Zhao Z X,Ishikawa Yuzo.Regional characteristics of crustal stress field and tectonic motions in and around Chinese mainland.Chinese J.Geophys.(in Chinese),2008,51(3):770-781.
[32]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.
[33]Wang Q,Zhang P Z,Freymueller J T,et al.Present-day crustal deformation in China constrained by Global Positioning System measurements.Science,2001,294(5542):574-577.
[34]张国民,马宏生,王辉等.中国大陆活动地块与强震活动关系.中国科学D辑:地球科学,2004,34(7):591-599.Zhang G M,Ma H S,Wang H,et al.Active tectonic blocks on the Chinese mainland and its relationwith strong earthquakes.Science in China(Series D)(in Chinese),2004,34(7):591-599.
[35]虢顺民,江在森,张崇立.青藏高原东北缘晚第四纪块体划分与运动态势研究.地震地质,2000,22(3):219-231.Guo S M,Jiang Z S,Zhang C L.Division and motion status of blocks for the northeastern Tibetan Plateau in LateQuaternary.Seismology and Geology(in Chinese),2000,22(3):219-231.
[36]周民都,张元生,石雅鏐等.青藏高原东北缘地壳三维速度结构.地球物理学进展,2006,21(1):127-134.Zhou M D,Zhang Y S,Shi Y L,et al.Three-dimensional crustal velocity structure in the northeastern margin of the Qinghai-Tibetan plateau.Progress in Geophysics(in Chinese),2006,21(1):127-134.
[37]王萍,王增光.阿拉善活动块体的划分及归宿.地震,1997,17(1):103-112.Wang P,Wang Z G.Division of the Alxa Block and its attribution.Earthquake(in Chinese),1997,17(1):103-112.
[38]吴晶,高原,陈运泰等.首都圈西北部地区地壳介质地震各向异性特征初步研究.地球物理学报,2007,50(1):209-220.Wu J,Gao Y,Chen Y T,et al.Seismic anisotropy in the crust in northwestern capital area of China.Chinese J.Geophys.(in Chinese),2007,50(1):209-220.
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