首都圈东南部地区地壳介质各向异性
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摘要
基于首都圈地震台网2002—2005年的区域地震波形数据,采用剪切波分裂系统分析方法(SAM),计算得到首都圈东南部地区(38.5°N—39.85°N,115.5°E—118.5°E)24个台站的剪切波分裂参数.结果表明,首都圈东南部地区快剪切波平均偏振方向与区域最大主压应力方向相近,与华北地区GPS主压应变测量结果一致;但首都圈东南部盆地地区的剪切波分裂观测结果与首都圈西北部的隆起—盆地构造结合区的观测结果不同.这说明了不同的构造对观测结果具有一定的影响.研究还表明,台站附近的断层分布状态对观测结果影响很大,复杂的断层分布会加剧剪切波分裂测量结果的离散程度.本研究区域南部台站与北部台站的快剪切波偏振方向存在较大差异,这可能与该区南北部的构造及应力环境存在较大差异有关.
Shear-wave splitting parameters of 24 stations in southeastern Capital area (38.5°N--39.85°N, 115.5°E--118.5°E) are obtained with SAM(systematic analysis method of shear-wave splitting) based on the data from 2002 to 2005 of Capital Area Seismic Network (CASN). The results show that the average polarization of fast shear-wave in southeastern Capital area is consistent with regional maximum horizontal principal compressive stress in the area, and is also consistent with maximum horizontal principal compressive strain from GPS in Northern China. The average shear-wave splitting in southeastern Capital area (in basin) is different from that in northwestern Capital area where uplifts and basin exist, illustrating that different tectonics can show different shear-wave splitting results. Research also shows that the distribution of faults around stations can obviously affect the shear-wave splitting results, and complicated distribution of faults can result in much more scattering of shear-wave splitting. It is also shown that in the north and south of the interested area (southeastern Capital area), the polarizations of fast shear-wave are not very consistent, which may be related to differences in tectonic and stress for the two areas.
Shear-wave splitting parameters of 24 stations in southeastern Capital area (38.5°N--39.85°N, 115.5°E--118.5°E) are obtained with SAM(systematic analysis method of shear-wave splitting) based on the data from 2002 to 2005 of Capital Area Seismic Network (CASN). The results show that the average polarization of fast shear-wave in southeastern Capital area is consistent with regional maximum horizontal principal compressive stress in the area, and is also consistent with maximum horizontal principal compressive strain from GPS in Northern China. The average shear-wave splitting in southeastern Capital area (in basin) is different from that in northwestern Capital area where uplifts and basin exist, illustrating that different tectonics can show different shear-wave splitting results. Research also shows that the distribution of faults around stations can obviously affect the shear-wave splitting results, and complicated distribution of faults can result in much more scattering of shear-wave splitting. It is also shown that in the north and south of the interested area (southeastern Capital area), the polarizations of fast shear-wave are not very consistent, which may be related to differences in tectonic and stress for the two areas.
引文
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许忠淮.2001.东亚地区现今构造应力图的编制[J].地震学报,23[5]:492--501.
姚陈,王培德,陈运泰.1992.卢龙地区S波偏振与上地壳裂隙各向异性[J].地球物理学报,35[3]:305--315.
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Crampin S.1978.Seismic wave propagation through a cracked solid:Polarization as a possible dilatancy diagnostic[J].Geophys J R astr Soc,53:467--496.
Crampin S,Gao Y.2006.Areviewof techniques for measuring seismic shear-wave splitting above small earthquakes[J].Phys Earth Planet Interi,159[1/2]:1--14.
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Mller C.2001.Upper mantle seismic anisotropy beneath Antarctica and the Scotia Sea region[J].Geophys J Int,147:105--122.
Peng Z,Ben-Zion Y.2004.Systematic analysis of crustal anisotropy along the Karadere-Duzce branch of the North Ana-tolian fault[J].Geophys J Int,159:253--274.
Yao C,Wang P D,Lu Y M,Chen Y T.1993.Interpretation of shear-wave splittingin Datong area,northern China[J].Can J Expl Geophys,29[1]:341--351.
Zatsepin S V,Crampin S.1997.Modelling the compliance of crustal rock.I.Response of shear-wave splitting to differ-ential stress[J].Geophys J Int,129:477--494.
Zhang Z J,Li Y K,Lu D Y,Teng J W,Wang GJ.2000.Velocity and anisotropy structure of the crust inthe Dabieshanorogenic belt from wide-angle seismic data[J].Phys Earth Planet Interi,122:115--131.
高原,郑斯华,周蕙兰.1999.唐山地区快剪切波偏振图象及其变化[J].地球物理学报,42[2]:228--232.
高原,刘希强,梁维,郝平.2004.剪切波分裂系统分析方法[SAM]软件系统[J].中国地震,20[1]:101--107.
黄金莉,赵大鹏.2005.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[J].科学通报,50[4]:348--355.
嘉世旭,张先康.2005.华北不同构造块体地壳构造及其对比研究[J].地球物理学报,48[3]:611--620.
江在森,张希,陈兵,薛富平.2000.华北地区近期地壳水平运动与应力应变场特征[J].地球物理学报,43[5]:657--665.
赖院根,刘启元,陈九辉,刘洁,李顺成,郭飙,黄志斌.2006.首都圈地区横波分裂与地壳应力场特征[J].地球物理学报,49[1]:189--196.
石玉涛,高原,吴晶,罗艳,苏有锦.2006.云南地区地壳介质各向异性:快剪切波偏振特性的初步研究[J].地震学报,28[6]:574--585.
王夫运,张先康,陈棋福,陈颙,赵金仁,杨卓欣,潘素珍.2005.北京地区上地壳三维细结构层析成像[J].地球物理学报,48[2]:359--366.
吴晶,高原,陈运泰,黄金莉.2007.首都圈西北部地区地壳介质地震各向异性特征初步研究[J].地球物理学报,50[1]:209--220.
许忠淮.2001.东亚地区现今构造应力图的编制[J].地震学报,23[5]:492--501.
姚陈,王培德,陈运泰.1992.卢龙地区S波偏振与上地壳裂隙各向异性[J].地球物理学报,35[3]:305--315.
张国民,马宏生,王辉,李丽.2004.中国大陆活动地块与强震活动关系[J].中国科学[D辑],34[7]:591--599.
庄灿涛.1999.首都圈数字地震遥测台网的技术构成[J].地震地磁观测与研究,20[5]:23--28.
Crampin S.1978.Seismic wave propagation through a cracked solid:Polarization as a possible dilatancy diagnostic[J].Geophys J R astr Soc,53:467--496.
Crampin S,Gao Y.2006.Areviewof techniques for measuring seismic shear-wave splitting above small earthquakes[J].Phys Earth Planet Interi,159[1/2]:1--14.
Crampin S,Peacock S.2005.Areviewof shear-wave splittingin the compliant crack-critical anisotropic Earth[J].WaveMotion,41:59--77.
Crampin S,Volti T,Chastin S,Gudmundsson A,Stefnsson R.2002.Indication of high pore-fluid pressuresin a seismi-cally-active fault zone[J].Geophys J Int,151:F1--F2.
Gao Y,Crampin S.2003.Temporal variations of shear-wave splittinginfield andlaboratory studiesin China[J].J ApplGeophys,54:279--287.
Mller C.2001.Upper mantle seismic anisotropy beneath Antarctica and the Scotia Sea region[J].Geophys J Int,147:105--122.
Peng Z,Ben-Zion Y.2004.Systematic analysis of crustal anisotropy along the Karadere-Duzce branch of the North Ana-tolian fault[J].Geophys J Int,159:253--274.
Yao C,Wang P D,Lu Y M,Chen Y T.1993.Interpretation of shear-wave splittingin Datong area,northern China[J].Can J Expl Geophys,29[1]:341--351.
Zatsepin S V,Crampin S.1997.Modelling the compliance of crustal rock.I.Response of shear-wave splitting to differ-ential stress[J].Geophys J Int,129:477--494.
Zhang Z J,Li Y K,Lu D Y,Teng J W,Wang GJ.2000.Velocity and anisotropy structure of the crust inthe Dabieshanorogenic belt from wide-angle seismic data[J].Phys Earth Planet Interi,122:115--131.
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