川滇地区Lg波Q值层析成像
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摘要
利用云南和四川数字地震观测台网记录的数字化地震资料,开展了川滇地区不同频率的QLg层析成像研究,反演结果的空间分辨率小于100 km.反演结果表明,川滇地区介质的横向不均匀性强烈,QLg高低值差异显著.川滇地区显著的高衰减区有川滇菱形块体的东南边界(即沿鲜水河至安宁河以及思茅—澜沧—普洱区),滇西北地区、龙门山断裂以西松潘—茂文地区、巴塘及理塘强震区等,Lg波高衰减区的分布与构造活动强烈、强震活动或大震破裂造成介质破碎区、低速区等相关,表明构造活动强烈或大震破裂造成的介质破碎、热物质沿活动断裂上涌等可能是川滇地区低QLg的主要成因.显著的低衰减区有川东盆地、滇东南地区以及金沙江、怒江断裂的中段区域,滇中块体内部也呈现出相对的低衰减特征.Lg波低衰减区与地震活动性弱、速度正异常等相关,表明川滇地区Lg波的低衰减区与地壳变形、地震活动性及水热活动弱、块体稳定等有关.
In this study we obtained the tomography results of Q Lg in Sichuan-Yunnan region,separately for each frequency,by using seismic wave data recorded by Yunnan and Sichuan seismic networks.The spatial resolution of our result is less than 100 km.Our results demonstrate that strong heterogeneity exists in the studied region,showing large difference between the highest and lowest Q value.The obvious high attenuation regions include the southeast edge of Sichuan-Yunnan rhombic block from Xianshuihe fault zone to Anninghe fault zone,the Simao-Lancang-Pu′e region,the Songpan-Maowen region to the west of Longmenshan fault zone,as well as the Batang and Litang strong earthquake region.According to our result,high attenuation of Lg waves corresponds to strong seismic active zones,ruptured area of large earthquakes,high terrestrial heat activity,and low velocity.It demonstrates that broken medium caused by strong tectonic activity or large earthquakes and heat flow upwelling along active faults may be the main reasons of low Q Lg in Sichuan-Yunnan region.The obvious low attenuation regions include the Sichuan basin,the eastern block of Yunnan region,and the middle part of Jinshajiang and Nujiang fault zones.The interior of Dianzhong block also shows lower attenuation than the nearby area.Low attenuation regions correspond to the stable tectonic block,weak tectonic activity and high velocity.It shows that low attenuation of Lg wave in Sichuan-Yunnan region is correlated with small crustal deformation,low seismic activity,weak hydrothermal activities and stable block.
In this study we obtained the tomography results of Q Lg in Sichuan-Yunnan region,separately for each frequency,by using seismic wave data recorded by Yunnan and Sichuan seismic networks.The spatial resolution of our result is less than 100 km.Our results demonstrate that strong heterogeneity exists in the studied region,showing large difference between the highest and lowest Q value.The obvious high attenuation regions include the southeast edge of Sichuan-Yunnan rhombic block from Xianshuihe fault zone to Anninghe fault zone,the Simao-Lancang-Pu′e region,the Songpan-Maowen region to the west of Longmenshan fault zone,as well as the Batang and Litang strong earthquake region.According to our result,high attenuation of Lg waves corresponds to strong seismic active zones,ruptured area of large earthquakes,high terrestrial heat activity,and low velocity.It demonstrates that broken medium caused by strong tectonic activity or large earthquakes and heat flow upwelling along active faults may be the main reasons of low Q Lg in Sichuan-Yunnan region.The obvious low attenuation regions include the Sichuan basin,the eastern block of Yunnan region,and the middle part of Jinshajiang and Nujiang fault zones.The interior of Dianzhong block also shows lower attenuation than the nearby area.Low attenuation regions correspond to the stable tectonic block,weak tectonic activity and high velocity.It shows that low attenuation of Lg wave in Sichuan-Yunnan region is correlated with small crustal deformation,low seismic activity,weak hydrothermal activities and stable block.
引文
[1]Ruzaikin A I,Nersesov I L,Molnar P.Propagation of Lgand lateral variations of crustal structure of Asia.J GeophysRes,1977,82:307~316
[2]Kennett B L N.Lg waves and structural boundaries.BullSeism Soc Am,1986,77:1133~1141
[3]Mitchell B J,Pan Y,Xie J,et al.Lg codaQvariation acrossEurasia andits relation to evolution.J Geophys Res,1997,102:22767~22777
[4]Xie J,Nuttli O W.Interpretation of high-frequency coda atlarge distances,stochastic modeling and method of inversion.Geophys J Int,1988,95(2):579~595
[5]Xie J,Mitchell B J.A back projection method for i maginglarge-scale lateral variation of Lg codaQwith application tocontinental Africa.Geophys J Int,1990,100(1):161~181
[6]Mitchell B J,Bager S,Akinci A,et al.Lg codaQinAustralia and its relation to crustal structure and evolution.Pure and Appl Geophys,1998,153:639~657
[7]Xie J,Wu Z,Liu R,et al.Tomographic regionalization ofcrustal LgQin eastern Eurasia.Geophy Reserch Letters,2006,33,L03315,doi:10.1029/2005GL024410
[8]胡家富,丛连理,苏有锦等.云南及周边地区Lg尾波Q值的分布特征.地球物理学报,2003,46(5):800~813Hu J F,Cong L L,Su YJ,et al.Distribution characteristicsofQvalue of the Lg codain Yunnan andits′adjacent regions.Chinese J Geophys(in Chinese),2003,46(5):800~813
[9]苏伟,吴建平,明跃红等.Lg尾波Q0值与中国大陆及邻区的地质构造关系,地震学报,2006,28(2):132~140Su W,Wu J P,Ming Y H,et al.Lg codaQ0value and itsrelation with the tectonics in Chinese mainland and adjacentregions.Acta Seismologica Sinica(in Chinese),2006,28(2):132~140
[10]丛连理,胡家富,傅竹武等.中国大陆及邻近地区Lg尾波Q值的分布,中国科学(D辑),2002,32(8):617~624Cong L L,Hu J F,Fu Z W,et al.Lg codaQ0value and itsrelation with the tectonics in Chinese mainland and adjacentregions.Science in China(Ser.D)(in Chinese),2002,32(8):617~624
[11]刘建华,刘福田,阎晓蔚等.华北地区Lg尾波衰减研究—Lg尾波Q的测量,地球物理学报,2004,47(5):822~831Liu J H,Liu F T,Yan X W,et al.A study of Lg codaattenuationin North China—the measurement of Lg codaQ.Chinese J Geophys,(in Chinese),2004,47(5):822~831
[12]Ojeda A,Ottemo¨ller Lars.QLgtomography in Colombia.Physics of the Earth and Planetary Interiors,2002,130:253~270
[13]Ottemo¨ller L,Nikolai M,Shapiro,et al.Lateral variation ofLg wave propagation in southern Mexico.J Geophys Res,2002,107(B1),ESE3-1-3-13
[14]Ottemo¨ller L,Lg waveQtomography in Central America.Geophys J Int,2002,150:295~302
[15]苏有锦,秦嘉政.川滇地区强地震活动与区域新构造运动的关系.中国地震,2001,17(1):24~34Su Y J,Qin J Z.The relationship of heavy earthquakeactative and local newtectonic movement in Sichuan-Yunnanarea.China Earthquake(in Chinese),2001,17(1):24~34
[16]韩渭宾,蒋国芳.川滇地区强震活动分布特征及其与地壳块体构造背景关系的研究.地震学报,2004,26(2):211~222Han WB,Jiang G F.Study on distribution characteristics ofstrong earthquakes in Sichuan-Yunnan area and theirgeological tectionic background.Acta Seismologica Sinica(inChinese),2004,26(2):211~222
[17]阚荣举,张四昌,晏凤桐等.我国西南地区现代构造应力场与现代构造活动特征的探讨.地理物理学报,1977,29(2):96~108Kan RJ,Zhang S C,Yan F T,et al.Study on the currenttectonic stress field and the characteristics of current tectonicactivity in southwest China.Chinese J Geophys(inChinese),1977,29(2):96~108
[18]宋方敏,汪一鹏等.中国活断层研究专辑—小江活动断裂带.北京:地震出版社,1998Song F M,Wang Y P,et al.Active Segment Study Special-Xiaojiang Active Fault Zone(in Chinese).Beijing:SeismologicalPress,1988
[19]黄汲清,任纪舜,姜春发等.中国大地构造及演化.北京:科学出版社,1980Huang J Q,Ren J S,Jiang C F,et al.Tectonic Structureand Evolution of China(in Chinese).Beijing:Science Press,1980
[20]滕吉文.康滇构造带岩石圈物理与动力学.北京:科学出版社,1994Teng J W.Physics and Dynamic of Lithosphere of Kang-DianTectonic Belt(in Chinese).Beijing:Science Press,1994
[21]苏有锦,刘祖荫,蔡民军.云南地区强震分布的深部地球介质背景.地震学报,1999,21(3):313~322Su YJ,Liu Z Y,Cai MJ.Deep-earth mediumbackground ofstrong earthquakes distribution in Yunnan province.ActaSeismologica Sinica(in Chinese),1999,21(3):313~322
[22]Menke W.Geophysical Data Analysis:Discrete InverseTheory.Int Geophys Ser,Academic,San Diego,Calif,1989,Vol45,289
[23]Press W H,Flannery B P,Teukolsky S A,et al.Numericalcontinental margins.Geophys J Int,1986,98:107~130
[24]Barmin M P,Ritzwoller M H,Levshin A L.A fast andreliable method for surface wave tomography.Pure ApplGeophys,2001,158:1351~1375
[25]Chael E.Spectral scaling of earthquakes in the Miramichiregion of NewBrunswick.Bull SeismSoc Am,1977,77(2):347~365
[26]马宏生,汪素云,裴顺平等.川滇及周边地区地壳横波衰减的成像研究.地球物理学报,2007,50(2):465~471Ma HS,Wang S Y,Pei S P,et al.Q0tomography of S waveattenuationin Sichuan-Yunnan and adjacent regions.ChineseJ Geophys(in Chinese),2007,50(2):465~471
[27]王椿镛,Mooney WD,王溪莉等.川滇地区地壳上地幔三维速度结构研究.地震学报,2002,24:1~16Wang C Y,Mooney W D,Wang X L,et al.Study on 3-Dvelocity structure of crust and upper mantle in Sichuan-Yunnan region,China.Acta Seismologica Sinica(inChinese),2002,24:1~16
[28]苏有锦,刘杰,郑斯华等.云南地区S波非弹性衰减Q值研究.地震学报,2006,28(2):206~212Su YJ,Liu J,Zheng S H,et al.Qvalue of anelastic-waveattenuation in Yunnan region,China.Acta SeismologicaSinica(in Chinese),2006,28(2):206~212
[2]Kennett B L N.Lg waves and structural boundaries.BullSeism Soc Am,1986,77:1133~1141
[3]Mitchell B J,Pan Y,Xie J,et al.Lg codaQvariation acrossEurasia andits relation to evolution.J Geophys Res,1997,102:22767~22777
[4]Xie J,Nuttli O W.Interpretation of high-frequency coda atlarge distances,stochastic modeling and method of inversion.Geophys J Int,1988,95(2):579~595
[5]Xie J,Mitchell B J.A back projection method for i maginglarge-scale lateral variation of Lg codaQwith application tocontinental Africa.Geophys J Int,1990,100(1):161~181
[6]Mitchell B J,Bager S,Akinci A,et al.Lg codaQinAustralia and its relation to crustal structure and evolution.Pure and Appl Geophys,1998,153:639~657
[7]Xie J,Wu Z,Liu R,et al.Tomographic regionalization ofcrustal LgQin eastern Eurasia.Geophy Reserch Letters,2006,33,L03315,doi:10.1029/2005GL024410
[8]胡家富,丛连理,苏有锦等.云南及周边地区Lg尾波Q值的分布特征.地球物理学报,2003,46(5):800~813Hu J F,Cong L L,Su YJ,et al.Distribution characteristicsofQvalue of the Lg codain Yunnan andits′adjacent regions.Chinese J Geophys(in Chinese),2003,46(5):800~813
[9]苏伟,吴建平,明跃红等.Lg尾波Q0值与中国大陆及邻区的地质构造关系,地震学报,2006,28(2):132~140Su W,Wu J P,Ming Y H,et al.Lg codaQ0value and itsrelation with the tectonics in Chinese mainland and adjacentregions.Acta Seismologica Sinica(in Chinese),2006,28(2):132~140
[10]丛连理,胡家富,傅竹武等.中国大陆及邻近地区Lg尾波Q值的分布,中国科学(D辑),2002,32(8):617~624Cong L L,Hu J F,Fu Z W,et al.Lg codaQ0value and itsrelation with the tectonics in Chinese mainland and adjacentregions.Science in China(Ser.D)(in Chinese),2002,32(8):617~624
[11]刘建华,刘福田,阎晓蔚等.华北地区Lg尾波衰减研究—Lg尾波Q的测量,地球物理学报,2004,47(5):822~831Liu J H,Liu F T,Yan X W,et al.A study of Lg codaattenuationin North China—the measurement of Lg codaQ.Chinese J Geophys,(in Chinese),2004,47(5):822~831
[12]Ojeda A,Ottemo¨ller Lars.QLgtomography in Colombia.Physics of the Earth and Planetary Interiors,2002,130:253~270
[13]Ottemo¨ller L,Nikolai M,Shapiro,et al.Lateral variation ofLg wave propagation in southern Mexico.J Geophys Res,2002,107(B1),ESE3-1-3-13
[14]Ottemo¨ller L,Lg waveQtomography in Central America.Geophys J Int,2002,150:295~302
[15]苏有锦,秦嘉政.川滇地区强地震活动与区域新构造运动的关系.中国地震,2001,17(1):24~34Su Y J,Qin J Z.The relationship of heavy earthquakeactative and local newtectonic movement in Sichuan-Yunnanarea.China Earthquake(in Chinese),2001,17(1):24~34
[16]韩渭宾,蒋国芳.川滇地区强震活动分布特征及其与地壳块体构造背景关系的研究.地震学报,2004,26(2):211~222Han WB,Jiang G F.Study on distribution characteristics ofstrong earthquakes in Sichuan-Yunnan area and theirgeological tectionic background.Acta Seismologica Sinica(inChinese),2004,26(2):211~222
[17]阚荣举,张四昌,晏凤桐等.我国西南地区现代构造应力场与现代构造活动特征的探讨.地理物理学报,1977,29(2):96~108Kan RJ,Zhang S C,Yan F T,et al.Study on the currenttectonic stress field and the characteristics of current tectonicactivity in southwest China.Chinese J Geophys(inChinese),1977,29(2):96~108
[18]宋方敏,汪一鹏等.中国活断层研究专辑—小江活动断裂带.北京:地震出版社,1998Song F M,Wang Y P,et al.Active Segment Study Special-Xiaojiang Active Fault Zone(in Chinese).Beijing:SeismologicalPress,1988
[19]黄汲清,任纪舜,姜春发等.中国大地构造及演化.北京:科学出版社,1980Huang J Q,Ren J S,Jiang C F,et al.Tectonic Structureand Evolution of China(in Chinese).Beijing:Science Press,1980
[20]滕吉文.康滇构造带岩石圈物理与动力学.北京:科学出版社,1994Teng J W.Physics and Dynamic of Lithosphere of Kang-DianTectonic Belt(in Chinese).Beijing:Science Press,1994
[21]苏有锦,刘祖荫,蔡民军.云南地区强震分布的深部地球介质背景.地震学报,1999,21(3):313~322Su YJ,Liu Z Y,Cai MJ.Deep-earth mediumbackground ofstrong earthquakes distribution in Yunnan province.ActaSeismologica Sinica(in Chinese),1999,21(3):313~322
[22]Menke W.Geophysical Data Analysis:Discrete InverseTheory.Int Geophys Ser,Academic,San Diego,Calif,1989,Vol45,289
[23]Press W H,Flannery B P,Teukolsky S A,et al.Numericalcontinental margins.Geophys J Int,1986,98:107~130
[24]Barmin M P,Ritzwoller M H,Levshin A L.A fast andreliable method for surface wave tomography.Pure ApplGeophys,2001,158:1351~1375
[25]Chael E.Spectral scaling of earthquakes in the Miramichiregion of NewBrunswick.Bull SeismSoc Am,1977,77(2):347~365
[26]马宏生,汪素云,裴顺平等.川滇及周边地区地壳横波衰减的成像研究.地球物理学报,2007,50(2):465~471Ma HS,Wang S Y,Pei S P,et al.Q0tomography of S waveattenuationin Sichuan-Yunnan and adjacent regions.ChineseJ Geophys(in Chinese),2007,50(2):465~471
[27]王椿镛,Mooney WD,王溪莉等.川滇地区地壳上地幔三维速度结构研究.地震学报,2002,24:1~16Wang C Y,Mooney W D,Wang X L,et al.Study on 3-Dvelocity structure of crust and upper mantle in Sichuan-Yunnan region,China.Acta Seismologica Sinica(inChinese),2002,24:1~16
[28]苏有锦,刘杰,郑斯华等.云南地区S波非弹性衰减Q值研究.地震学报,2006,28(2):206~212Su YJ,Liu J,Zheng S H,et al.Qvalue of anelastic-waveattenuation in Yunnan region,China.Acta SeismologicaSinica(in Chinese),2006,28(2):206~212
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