横波分裂研究方法分析及中国大陆地区横波分裂的构造含义
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摘要
利用中国国家台网2001—2005年的数据,采用SC1991和WS1998的方法,通过分析SKS和SKKS震相,获得了中国大陆地区国家地震基准观测台的分裂参数。各台站的结果差异较大。西南部、南部、西北部分裂时间比华北及中西部的分裂时间要少。快方向与GPS速度场的一致性表明岩石圈与软流圈的耦合现象。快方向在板块会聚带平行于板块边界,在走滑断层处平行于断层走向。这些都可能表明地壳与地幔的一致变形。讨论了时间窗的截取长度、射线分裂的可能性和快方向随后方位角的变化。
Shear-wave splitting is the most simple and direct seismic method to understand the anisotropic property of the earth.The result has important meaning in geodynamics and valuable in the research of earthquake prediction.The authors use the methods proposed by SC1991 and WS1998 to constrain the splitting parameters by analyzing SKS and SKKS phases.The records from 2001 to 2005 are provided by Chinese Seismology Network Center (CENC).Great discrepancies are observed.The splitting time in South-West,South,and North-West part of China is shorter than Middle and Middle-West part of China.Similar patterns between fast direction and GPS velocity direction show coupling effect between lithosphere and asthenosphere.Fast directions are also parallel to plate boundaries in convergent regions and identical to the strike of transcurrent fault.This may imply the coherent deformation between crust and mantle.The length of time window,the possibility of ray-splitting and the dependence of fast direction to back-azimuth are also discussed.
Shear-wave splitting is the most simple and direct seismic method to understand the anisotropic property of the earth.The result has important meaning in geodynamics and valuable in the research of earthquake prediction.The authors use the methods proposed by SC1991 and WS1998 to constrain the splitting parameters by analyzing SKS and SKKS phases.The records from 2001 to 2005 are provided by Chinese Seismology Network Center (CENC).Great discrepancies are observed.The splitting time in South-West,South,and North-West part of China is shorter than Middle and Middle-West part of China.Similar patterns between fast direction and GPS velocity direction show coupling effect between lithosphere and asthenosphere.Fast directions are also parallel to plate boundaries in convergent regions and identical to the strike of transcurrent fault.This may imply the coherent deformation between crust and mantle.The length of time window,the possibility of ray-splitting and the dependence of fast direction to back-azimuth are also discussed.
引文
[1]Savage M K.Seismic anisotropy and mantle deformation:what have we learned from shear wave splitting.Rev Geophys,1999,37:65-106
[2]Long M D,Van der Hilst R D.Estimating shear-wave splitting parameters from broadband recordings in Japan:a comparison of three methods.Bull Seism Soc Am,2005,95:1346-1358
[3]Silver P G.Seismic anisotropy beneath the continents:probing the depths of geology.Ann Rev Earth Planet Sci,1996,24:385-432
[4]Becker T W,Browaeys J T,Jordan T H.Stochastic analysis of shear-wave splitting length scales.Earth Planet Sci Let,2007,259:526-540
[5]Fu Y,Chen Y J,Li A,et al.Indian mantle corner flow at Southern Tibet from shear-wave splitting study.Geophy Res Lett,2008,35:L02308
[6]王椿镛,常利军,吕智勇,等.青藏高原东部上地幔各向异性及相关的壳幔耦合型式.中国科学:D辑,2007,37(4):495-503
[7]常利军,王椿镛,丁志峰,等.青藏高原东北缘上地幔各向异性研究.地球物理学报,2008,51(2):431-438
[8]Silver P G,Gao S S,Liu K H,et al.Mantle deformation beneath Southern Africa.Geophy Res Lett,2001,28:2493-2496
[9]Silver P G,Chan W W.Shear wave splitting and mantle deformation.J Geophys Res,1991,96:16429-16454
[10]Wolfe C J,Silver P G.Seismic anisotropy of oceanic upper mantle:shear wave splitting methodologies and observations.J Geophys Res,1998,103:749-771
[11]Silver P G,Savage M K.The interpretation of shear-wave splitting parameters in the presence of two anisotropic layers.Geophys J Int,1994,119:949-963
[12]郑秀芬,欧阳飚,张东宁,等.“国家数字测震台网数据备份中心”技术系统建设及其对汶川大地震研究的数据支撑.地球物理学报,2009,52(5):1412-1417
[13]Fouch M.Upper mantle anisotropy database.(2003-11-12)[2008-01-02].http://geophysics.asu.edu/anisotropy/upper Accessed in01/2008
[14]Lev E,Long M D,Van der Hilst R D.Seismic anisotropy in Eastern Tibet from shear wave splitting reveals changes in lithospheric deformation.Earth Planet Sci Lett,2006,251:293-304
[15]郑斯华,高原.中国大陆岩石层的方位各向异性.地震学报,1994,16(2):131-140
[16]罗艳,黄忠贤,彭艳菊,等.中国大陆及邻区SKS波分裂研究.地球物理学报,2004,47(5):812-821
[17]彭艳菊,黄忠贤,苏伟,等.中国大陆及邻区海域地壳上地幔各向异性研究.地球物理学报,2007,50(3):752-759
[18]张培震,王琪,马宗晋.中国大陆现今构造运动的GPS速度场与活动地块.地学前缘,2002,9(2):430-441
[19]Fouch M J,Fischer K M,Parmentier E M,et al.Shear wave splitting,continental keels,and patterns of mantle flow.J Geophys Res,2000,105:6255-6275
[20]万天丰.中国大地构造学纲要.北京:地质出版社,2004
[21]赖锡安,黄立人,徐菊生,等.中国大陆现今地壳运动.北京:地震出版社,2004
[22]Huang W C,James F N,Tilmann F,et al.Seismic polarization anisotropy beneath the central Tibetan Plateau.J Geophys Res,2000,105(27):979-989
[23]郑秀芬,陈朝辉,张春贺.1999年台湾集集地震余震区:嘉义地区地震的剪切波分裂参数随时间变化的研究.地球物理学报,2008,51(1):149-157
[2]Long M D,Van der Hilst R D.Estimating shear-wave splitting parameters from broadband recordings in Japan:a comparison of three methods.Bull Seism Soc Am,2005,95:1346-1358
[3]Silver P G.Seismic anisotropy beneath the continents:probing the depths of geology.Ann Rev Earth Planet Sci,1996,24:385-432
[4]Becker T W,Browaeys J T,Jordan T H.Stochastic analysis of shear-wave splitting length scales.Earth Planet Sci Let,2007,259:526-540
[5]Fu Y,Chen Y J,Li A,et al.Indian mantle corner flow at Southern Tibet from shear-wave splitting study.Geophy Res Lett,2008,35:L02308
[6]王椿镛,常利军,吕智勇,等.青藏高原东部上地幔各向异性及相关的壳幔耦合型式.中国科学:D辑,2007,37(4):495-503
[7]常利军,王椿镛,丁志峰,等.青藏高原东北缘上地幔各向异性研究.地球物理学报,2008,51(2):431-438
[8]Silver P G,Gao S S,Liu K H,et al.Mantle deformation beneath Southern Africa.Geophy Res Lett,2001,28:2493-2496
[9]Silver P G,Chan W W.Shear wave splitting and mantle deformation.J Geophys Res,1991,96:16429-16454
[10]Wolfe C J,Silver P G.Seismic anisotropy of oceanic upper mantle:shear wave splitting methodologies and observations.J Geophys Res,1998,103:749-771
[11]Silver P G,Savage M K.The interpretation of shear-wave splitting parameters in the presence of two anisotropic layers.Geophys J Int,1994,119:949-963
[12]郑秀芬,欧阳飚,张东宁,等.“国家数字测震台网数据备份中心”技术系统建设及其对汶川大地震研究的数据支撑.地球物理学报,2009,52(5):1412-1417
[13]Fouch M.Upper mantle anisotropy database.(2003-11-12)[2008-01-02].http://geophysics.asu.edu/anisotropy/upper Accessed in01/2008
[14]Lev E,Long M D,Van der Hilst R D.Seismic anisotropy in Eastern Tibet from shear wave splitting reveals changes in lithospheric deformation.Earth Planet Sci Lett,2006,251:293-304
[15]郑斯华,高原.中国大陆岩石层的方位各向异性.地震学报,1994,16(2):131-140
[16]罗艳,黄忠贤,彭艳菊,等.中国大陆及邻区SKS波分裂研究.地球物理学报,2004,47(5):812-821
[17]彭艳菊,黄忠贤,苏伟,等.中国大陆及邻区海域地壳上地幔各向异性研究.地球物理学报,2007,50(3):752-759
[18]张培震,王琪,马宗晋.中国大陆现今构造运动的GPS速度场与活动地块.地学前缘,2002,9(2):430-441
[19]Fouch M J,Fischer K M,Parmentier E M,et al.Shear wave splitting,continental keels,and patterns of mantle flow.J Geophys Res,2000,105:6255-6275
[20]万天丰.中国大地构造学纲要.北京:地质出版社,2004
[21]赖锡安,黄立人,徐菊生,等.中国大陆现今地壳运动.北京:地震出版社,2004
[22]Huang W C,James F N,Tilmann F,et al.Seismic polarization anisotropy beneath the central Tibetan Plateau.J Geophys Res,2000,105(27):979-989
[23]郑秀芬,陈朝辉,张春贺.1999年台湾集集地震余震区:嘉义地区地震的剪切波分裂参数随时间变化的研究.地球物理学报,2008,51(1):149-157
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