首都圈地区的地壳厚度及泊松比
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摘要
利用2002～2003年中国地震局地质研究所台阵实验室以唐山大震区为中心布设的40个流动宽频带地震台站和首都圈数字台网的107个固定台站的远震数据,采用接收函数叠加搜索方法测定了首都圈地区地壳厚度和平均泊松比.综合利用首都圈数字地震台网的宽频带和短周期台站,以及流动地震台阵的观测数据,使我们的结果具有较前人更好的空间分辨率,为我们研究首都圈地壳的变形及其与地震的关系提供了重要的数据平台.结果表明:(1)首都圈地区地壳厚度和泊松比具有明显的横向分块特征,并与断层切割的地质块体有较好的相关性,地壳厚度变化形成了由涵盖北京—三河—唐山的NE向地壳厚度变化过渡带与张家口—北京—天津的NW向壳幔界面凹陷带构成的交汇构造,后者与所谓的张家口—渤海地震带基本吻合,而且本文给出的深部构造背景与首都圈地区的NE向和NW向地震带的交汇特征相吻合;(2)首都圈地区地壳厚度具有较大的差异,区域内地壳厚度的变化达15km.其中,台站SZJ下方地壳厚度达到43.8km,而台站BDH下方地壳厚度仅为28.8km,总体上研究区西北侧的张家口—怀来地区的地壳厚度较大(～40km),而唐山以东地区地壳较薄(28～32km);(3)研究区地壳的平均泊松比值为0.26左右,其最大值偏离泊松介质(σ=0.25)21%以上,而最小值偏离标准泊松比值9.6%,北京周边地区被高泊松比的介质环绕,而唐山东侧为低泊松比介质,地壳泊松比的分布特征反映了华北克拉通裂解过程中地幔物质的侵入;(4)研究区中强地震大多发生在地壳厚度和泊松比变化的陡变带,且偏于低泊松比的一侧,首都圈地震的成因仅考虑由于板块作用引起的水平应力场是不够的,有必要充分重视由于上地幔变形引起的地壳垂直变形和上地幔物质侵入造成的地壳变形运动与热效应.
Simultaneously using the teleseismic waveform data recorded by 40 movable stations deployed by Laboratory of Lithospheric Seismic Array,Institute of Geology,China Earthquake Administration and 107 permanent stations of the Digital Network of the Capital Circle,we investigate the crustal thickness and averaged Poisson's ratios beneath the stations by means of the grid-stacking-search method of receiver functions.Simultaneously using the data recorded by the broadband stations and short period stations makes our results have much higher spatial resolution than those given by the previous studies.Our results provide a data base for investigating the relationship between the earthquakes and crustal deformation.Our results show that:(1)the distribution of the crustal thickness and Poisson's ratio over the Capital Circle region has an obvious laterally blocked feature related closely to the geological blocks incised by the faults.The variations of the crust thickness reveal a structural intersection of the transition zone along the NE direction through Beijing-Sanhe-Tangshan area and the depressed Moho belt along the NW direction across Zhangjiakou-Beijing-Tianjin region,which is roughly in accordance with the so-called Zhangjiakou-Bohai seismic belt,and the deep structure background given by this study is in accordance with the characteristic of NE and NW earthquake zones in the Capital Circle region.(2)The crustal thickness has a large variation of 15 km over the Capital Circle region.The crustal thickness is 43.8 km beneath the station SZJ,and the crust thickness beneath the station BDH is only 28.8 km.In general,the crustal thickness is ~40 km in the Zhangjiakou-Huailai region located at the northwestern side of the Capital Circle,and it becomes thinner(28~32 km)in the area east to Tangshan city.(3)The averaged Poisson's ratio is about 0.26 over the area investigated.In comparison with the Poisson medium(σ=0.25),its maximum deviates 21%,and the minimum deviates 9.6%.The adjacent area surrounding the Beijing city has a high Poisson's ratio,and the Poisson's ratio of the area east to Tangshan is lower.The Poisson's ratio distribution reveals the mantle material intrusions in the splitting process of the North China craton.(4)The middle and large earthquakes mostly took place in the abrupt variation belt of the crustal thickness and the Poisson's ratio,and locate in the region with a lower Poisson's ratio.Only considering the horizontal stress field caused by plate movement is not adequate for earthquake genesis in the Capital Circle and it will be necessary simultaneously considering the vertical crustal deformation caused by the upper mantle movement as well as the thermal effects due to the upper mantle material intrusion.
Simultaneously using the teleseismic waveform data recorded by 40 movable stations deployed by Laboratory of Lithospheric Seismic Array,Institute of Geology,China Earthquake Administration and 107 permanent stations of the Digital Network of the Capital Circle,we investigate the crustal thickness and averaged Poisson's ratios beneath the stations by means of the grid-stacking-search method of receiver functions.Simultaneously using the data recorded by the broadband stations and short period stations makes our results have much higher spatial resolution than those given by the previous studies.Our results provide a data base for investigating the relationship between the earthquakes and crustal deformation.Our results show that:(1)the distribution of the crustal thickness and Poisson's ratio over the Capital Circle region has an obvious laterally blocked feature related closely to the geological blocks incised by the faults.The variations of the crust thickness reveal a structural intersection of the transition zone along the NE direction through Beijing-Sanhe-Tangshan area and the depressed Moho belt along the NW direction across Zhangjiakou-Beijing-Tianjin region,which is roughly in accordance with the so-called Zhangjiakou-Bohai seismic belt,and the deep structure background given by this study is in accordance with the characteristic of NE and NW earthquake zones in the Capital Circle region.(2)The crustal thickness has a large variation of 15 km over the Capital Circle region.The crustal thickness is 43.8 km beneath the station SZJ,and the crust thickness beneath the station BDH is only 28.8 km.In general,the crustal thickness is ~40 km in the Zhangjiakou-Huailai region located at the northwestern side of the Capital Circle,and it becomes thinner(28~32 km)in the area east to Tangshan city.(3)The averaged Poisson's ratio is about 0.26 over the area investigated.In comparison with the Poisson medium(σ=0.25),its maximum deviates 21%,and the minimum deviates 9.6%.The adjacent area surrounding the Beijing city has a high Poisson's ratio,and the Poisson's ratio of the area east to Tangshan is lower.The Poisson's ratio distribution reveals the mantle material intrusions in the splitting process of the North China craton.(4)The middle and large earthquakes mostly took place in the abrupt variation belt of the crustal thickness and the Poisson's ratio,and locate in the region with a lower Poisson's ratio.Only considering the horizontal stress field caused by plate movement is not adequate for earthquake genesis in the Capital Circle and it will be necessary simultaneously considering the vertical crustal deformation caused by the upper mantle movement as well as the thermal effects due to the upper mantle material intrusion.
引文
[1]国家地震局《一九七六年唐山大地震》编辑组.一九七六年唐山大地震.北京:地震出版社,1982State Seismological Bureau of China.1976Great Tangshan Earthquake(in Chinese).Beijing:Seismological Press,1982
[2]曾融生,张少泉,周海南等.唐山地震区的地壳结构及大陆地震成因的探讨.地震学报,1985,7(2):125～142Zeng R S,Zhang S Q,Zhou H N,et al.Crustal structure ofTangshan epicentral region andits relation to the seismogenic process of a continental earthquake.Acta Seismologica Sinica(in Chinese),1985,7(2):125～142
[3]Shao X Z,Zhang J R,Liu Q Y,et al.The common features of deep structuresin somelarge earthquake areas of the north China plain and their implication for earthquake site prediction.J.Phys.Earth.,1986,34(Suppl.):S223～S239
[4]朱露培,曾融生,刘福田.京津唐张地区地壳上地幔三维P波速度结构.地球物理学报,1990,33(3):267～277Zhu L P,Zeng R S,Liu F T.Three dimensional P-wave velocity structure under the Beijing network area.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1990,33(3):267～277
[5]孙若眛,刘福田.京津唐地区地壳结构与强震的发生—I.P波速度结构.地球物理学报,1995,38(5):563～572Sun R M,Liu F T.Crustal structure and strong earthquakes in Beijing,Tianjing,Tangshan area:I.P wave velocity structure.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1995,38(5):563～572
[6]孙若眛,赵燕来,吴丹.京津唐地区地壳结构与强震的发生—II.S波速度结构.地球物理学报,1996,39(3):347～355Sun R M,Zhao Y L,Wu D.Crustal structure and strong earthquakes in Beijing,Tianjing,Tangshan area:II.S wave velocity structure.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1996,39(3):347～355
[7]张先康,王椿镛,刘国栋等.延庆—怀来地区地壳细结构—利用深地震反射剖面.地球物理学报,1996,39(3):356～363Zhang X K,Wang C Y,Liu G D,et al.Fine crustal structure in Yanqing─Huailai region by deep seismic reflection profiling.Chinese J.Geophys.(Acta Geophysica Sinica),1996,39(3):356～363
[8]刘启元,李顺成,沈杨等.延怀盆地及其邻区地壳上地幔速度结构的宽频带地震台阵研究.地球物理学报,1997,40(6):763～771Liu Q Y,Li S C,Shen Y,et al.Brodband seismic array study of the crust and upper mantle velocity structure beneath Yanhuai basin and its neighbouring region.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1997,40(6):763～771
[9]赖院根,刘启元,陈九辉等.首都圈地区横波分裂与地壳应力场特征.地球物理学报,2006,49(1):190～196Lai Y G,Liu Q Y,Chen J H,et al.Shear wave splitting and the features of the crustal stress field in the Capital Circle.Chinese J.Geophys.(in Chinese),2006,49(1):190～196
[10]李松林,张先康,宋占隆等.多条人工地震测深剖面资料联合反演首都圈三维地壳结构.地球物理学报,2001,44(3):361～368Li S L,Zhang X K,Song Z L,et al.Three dimensional crustal structure of the Capital area obtained by a joint invertion of DSS data from multiple profiles.Chinese J.Geophys.(in Chinese),2001,44(3):361～368
[11]于湘伟,陈运泰,王培德.京津唐地区三维P波速度结构.地震学报,2003,25(1):1～14Yu X W,Chen Y T,Wang P D.Three dimensional P wave velocity structure in Beijing,Tianjing,Tangshan area.Acta Seismologica Sinica(in Chinese),2003,25(1):1～14
[12]嘉世旭,齐诚,王夫运等.首都圈地壳网格化三维结构.地球物理学报,2005,48(6):1316～1324Jia S X,Qi C,Wang F Y,et a1.Three dimensiona1crustal gridded structure of the Capital area.Chinese J.Geophys.(in Chinese),2005,48(6):1316～1324
[13]黄金莉,赵大鹏.首都圈地区地壳三维P波速度细结构与强震孕育的深部构造环境.科学通报,2005,50(4):348～355Huang J L,Zhao D P.Three-dimension P-wave velocity structure of the crust beneath the captital circle and the deep tectonic environment of strong earthquake.Chinese Science Bulletin(in Chinese),2005,50(4):348～355
[14]Huang J L,Zhao D P.Crustal heterogeneity and seismotectonics of the region around Beijing,China.Tectonophysics,2004,385:159～180
[15]Zandt G,Ammon C J.Continental crust composition constrained by measurements of crustal Poisson's ration.Nature,1995,374:152～154
[16]Zhu L P,Kanamori H.Moho depth variation in south California from teleseismic receiver functions.J.Geophys.Res.,2000,105:2969～2980
[17]许卫卫,郑天愉.渤海湾盆地北西盆山边界地区泊松比分布.地球物理学报,2005,48(5):1077～1084Xu W W,Zheng T Y.Distribution of Poisson′s ratios in the northwestern basin-mountain boundary of the Bohai Bay Basin.Chinese J.Geophys.(in Chinese),2005,48(5):1077～1084
[18]邓起东,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):1020～1030Deng Q D,Zhang P Z,Ran Y K,et al.Basic characteristics of active tectonics in China.Science in China(Ser.D),2002,32(12):1020～1030
[19]顾功叙.中国地震目录.北京:科学出版社,1983Gu G X.China Seismic Catalogue.Beijing:Science Press,1983
[20]Christensen N I,Fountain D M.Constitution of the lower continental crust based on experimental studies of seismic velocities in granulite.Geol.Soc.Am.Bull.,1975,86:462～465
[21]Fountain D M,Christensen N I.Composotion of the continental crust and upper mantle:a review in geophysica framework of the continental United States.Mem.Geol.Soc.Am.,1989,172:711～742
[22]刘启元,王峻,陈九辉等.1976年唐山大地震的孕震环境:密集地震台阵观测得到的结果.地学前缘,2007,14(6):205～213Liu Q Y,Wang J,Chen J H,et al.Seismogenic tectonic environment of1976great Tangshan earthquake:results given by dense seismic array observations.Earth Science Frontier(in Chinese),2007,14(6):205～213
[23]刘启元,Kind R,李顺成.接收函数复谱比的最大或然性估计及非线性反演.地球物理学报,1996,39(4):500～511Liu Q Y,Kind R,Li S C.Maximal likelihood estimation and nonlinear inversion of the complex receiver function spectrum ratio.Chinese J.Geophys.(in Chinese),1996,39(4):500～511
[24]刘启元,Kind R.分离三分量远震接收函数的多道最大或然性反褶积方法.地震地质,2004,26(3):417～425Liu Q Y,Kind R.Multi-channel maximal likelihood deconvolution method for isolating3-component teleseismic receiver function.Seismology and Geology(in Chinese),2004,26(3):417～425
[25]Wu QJ,Li Y H,Zhang R Q,et al.Wavelet modeling of broad-band receiver functions.Geophys.J.Int.,2007,170:534～544
[26]Wu QJ,Li Y H,Zhang R Q,et al.Receiver functions from autoregressive deconvolution.Pure Appl.Geophys.,2007,164:2175～2192
[27]陈九辉.远震体波接收函数方法:理论与应用[博士学位论文].北京:中国地震局地质研究所,2007Chen J H.Teleseismic receiver function:theory and applications[Ph.D.dissertation](in Chinese).Beijing:Institute of Geology,CEA,2007
[2]曾融生,张少泉,周海南等.唐山地震区的地壳结构及大陆地震成因的探讨.地震学报,1985,7(2):125～142Zeng R S,Zhang S Q,Zhou H N,et al.Crustal structure ofTangshan epicentral region andits relation to the seismogenic process of a continental earthquake.Acta Seismologica Sinica(in Chinese),1985,7(2):125～142
[3]Shao X Z,Zhang J R,Liu Q Y,et al.The common features of deep structuresin somelarge earthquake areas of the north China plain and their implication for earthquake site prediction.J.Phys.Earth.,1986,34(Suppl.):S223～S239
[4]朱露培,曾融生,刘福田.京津唐张地区地壳上地幔三维P波速度结构.地球物理学报,1990,33(3):267～277Zhu L P,Zeng R S,Liu F T.Three dimensional P-wave velocity structure under the Beijing network area.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1990,33(3):267～277
[5]孙若眛,刘福田.京津唐地区地壳结构与强震的发生—I.P波速度结构.地球物理学报,1995,38(5):563～572Sun R M,Liu F T.Crustal structure and strong earthquakes in Beijing,Tianjing,Tangshan area:I.P wave velocity structure.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1995,38(5):563～572
[6]孙若眛,赵燕来,吴丹.京津唐地区地壳结构与强震的发生—II.S波速度结构.地球物理学报,1996,39(3):347～355Sun R M,Zhao Y L,Wu D.Crustal structure and strong earthquakes in Beijing,Tianjing,Tangshan area:II.S wave velocity structure.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1996,39(3):347～355
[7]张先康,王椿镛,刘国栋等.延庆—怀来地区地壳细结构—利用深地震反射剖面.地球物理学报,1996,39(3):356～363Zhang X K,Wang C Y,Liu G D,et al.Fine crustal structure in Yanqing─Huailai region by deep seismic reflection profiling.Chinese J.Geophys.(Acta Geophysica Sinica),1996,39(3):356～363
[8]刘启元,李顺成,沈杨等.延怀盆地及其邻区地壳上地幔速度结构的宽频带地震台阵研究.地球物理学报,1997,40(6):763～771Liu Q Y,Li S C,Shen Y,et al.Brodband seismic array study of the crust and upper mantle velocity structure beneath Yanhuai basin and its neighbouring region.Chinese J.Geophys.(Acta Geophysica Sinica)(in Chinese),1997,40(6):763～771
[9]赖院根,刘启元,陈九辉等.首都圈地区横波分裂与地壳应力场特征.地球物理学报,2006,49(1):190～196Lai Y G,Liu Q Y,Chen J H,et al.Shear wave splitting and the features of the crustal stress field in the Capital Circle.Chinese J.Geophys.(in Chinese),2006,49(1):190～196
[10]李松林,张先康,宋占隆等.多条人工地震测深剖面资料联合反演首都圈三维地壳结构.地球物理学报,2001,44(3):361～368Li S L,Zhang X K,Song Z L,et al.Three dimensional crustal structure of the Capital area obtained by a joint invertion of DSS data from multiple profiles.Chinese J.Geophys.(in Chinese),2001,44(3):361～368
[11]于湘伟,陈运泰,王培德.京津唐地区三维P波速度结构.地震学报,2003,25(1):1～14Yu X W,Chen Y T,Wang P D.Three dimensional P wave velocity structure in Beijing,Tianjing,Tangshan area.Acta Seismologica Sinica(in Chinese),2003,25(1):1～14
[12]嘉世旭,齐诚,王夫运等.首都圈地壳网格化三维结构.地球物理学报,2005,48(6):1316～1324Jia S X,Qi C,Wang F Y,et a1.Three dimensiona1crustal gridded structure of the Capital area.Chinese J.Geophys.(in Chinese),2005,48(6):1316～1324
[13]黄金莉,赵大鹏.首都圈地区地壳三维P波速度细结构与强震孕育的深部构造环境.科学通报,2005,50(4):348～355Huang J L,Zhao D P.Three-dimension P-wave velocity structure of the crust beneath the captital circle and the deep tectonic environment of strong earthquake.Chinese Science Bulletin(in Chinese),2005,50(4):348～355
[14]Huang J L,Zhao D P.Crustal heterogeneity and seismotectonics of the region around Beijing,China.Tectonophysics,2004,385:159～180
[15]Zandt G,Ammon C J.Continental crust composition constrained by measurements of crustal Poisson's ration.Nature,1995,374:152～154
[16]Zhu L P,Kanamori H.Moho depth variation in south California from teleseismic receiver functions.J.Geophys.Res.,2000,105:2969～2980
[17]许卫卫,郑天愉.渤海湾盆地北西盆山边界地区泊松比分布.地球物理学报,2005,48(5):1077～1084Xu W W,Zheng T Y.Distribution of Poisson′s ratios in the northwestern basin-mountain boundary of the Bohai Bay Basin.Chinese J.Geophys.(in Chinese),2005,48(5):1077～1084
[18]邓起东,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):1020～1030Deng Q D,Zhang P Z,Ran Y K,et al.Basic characteristics of active tectonics in China.Science in China(Ser.D),2002,32(12):1020～1030
[19]顾功叙.中国地震目录.北京:科学出版社,1983Gu G X.China Seismic Catalogue.Beijing:Science Press,1983
[20]Christensen N I,Fountain D M.Constitution of the lower continental crust based on experimental studies of seismic velocities in granulite.Geol.Soc.Am.Bull.,1975,86:462～465
[21]Fountain D M,Christensen N I.Composotion of the continental crust and upper mantle:a review in geophysica framework of the continental United States.Mem.Geol.Soc.Am.,1989,172:711～742
[22]刘启元,王峻,陈九辉等.1976年唐山大地震的孕震环境:密集地震台阵观测得到的结果.地学前缘,2007,14(6):205～213Liu Q Y,Wang J,Chen J H,et al.Seismogenic tectonic environment of1976great Tangshan earthquake:results given by dense seismic array observations.Earth Science Frontier(in Chinese),2007,14(6):205～213
[23]刘启元,Kind R,李顺成.接收函数复谱比的最大或然性估计及非线性反演.地球物理学报,1996,39(4):500～511Liu Q Y,Kind R,Li S C.Maximal likelihood estimation and nonlinear inversion of the complex receiver function spectrum ratio.Chinese J.Geophys.(in Chinese),1996,39(4):500～511
[24]刘启元,Kind R.分离三分量远震接收函数的多道最大或然性反褶积方法.地震地质,2004,26(3):417～425Liu Q Y,Kind R.Multi-channel maximal likelihood deconvolution method for isolating3-component teleseismic receiver function.Seismology and Geology(in Chinese),2004,26(3):417～425
[25]Wu QJ,Li Y H,Zhang R Q,et al.Wavelet modeling of broad-band receiver functions.Geophys.J.Int.,2007,170:534～544
[26]Wu QJ,Li Y H,Zhang R Q,et al.Receiver functions from autoregressive deconvolution.Pure Appl.Geophys.,2007,164:2175～2192
[27]陈九辉.远震体波接收函数方法:理论与应用[博士学位论文].北京:中国地震局地质研究所,2007Chen J H.Teleseismic receiver function:theory and applications[Ph.D.dissertation](in Chinese).Beijing:Institute of Geology,CEA,2007
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