龙滩水库地区P波、S波和尾波衰减
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摘要
利用发生在龙滩水库地区的144次ML≥1.0地震资料,研究了该地区地壳介质的衰减特征,并采用尾波归一化方法分别估算了P波、S波的品质因子QP和QS,用单次反散射模型计算了尾波品质因子Qc.结果表明,该地区上述3个值与频率的依赖关系分别为QP(f)=(7.43±0.78)f(1.05±0.06),QS(f)=(13.08±3.20)f(1.76±0.15),Qc(f)=(50.52±2.71)f(1.13±0.03),总体呈现低Q0和高η值的特点.在所研究的频带范围1—16Hz内,QS/QP比值均大于1,表明该地区体波衰减中散射可能起着较大作用.Qc与QS的比较结果表明,在小于8Hz时,QSQc.这可能是由于介质的多次散射作用的结果.
Seismic attenuation properties of the crust medium in Longtan,Guangxi,reservoir region have been investigated using digital seismogram data of 144 ML≥1.0 earthquakes occurred in the region.The extended coda-normalization method has been used to calculate the quality factors for P wave (QP) and S waves (QS),and the single back-scattering model was used to determine the quality factors for coda wave (Qc).The results show that the frequency dependent relationships of these three quality factors in the region are QP(f)=(7.43±0.78)f(1.05±0.06), QS(f)=(13.08±3.20)f(1.76±0.15) and Qc(f)=(50.52±2.71)f(1.13±0.03),respectively,indicating a property of low Q0 and high η.The ratio QS/QP is found to be greater than one for the frequency range (1--16 Hz) considered here,indicating scattering being an important factor of body wave attenuation in the region.A comparison between Qc and QS shows that QSQc for frequencies above 8 Hz.This may be attributed to the multiple scattering effect of the medium.
Seismic attenuation properties of the crust medium in Longtan,Guangxi,reservoir region have been investigated using digital seismogram data of 144 ML≥1.0 earthquakes occurred in the region.The extended coda-normalization method has been used to calculate the quality factors for P wave (QP) and S waves (QS),and the single back-scattering model was used to determine the quality factors for coda wave (Qc).The results show that the frequency dependent relationships of these three quality factors in the region are QP(f)=(7.43±0.78)f(1.05±0.06), QS(f)=(13.08±3.20)f(1.76±0.15) and Qc(f)=(50.52±2.71)f(1.13±0.03),respectively,indicating a property of low Q0 and high η.The ratio QS/QP is found to be greater than one for the frequency range (1--16 Hz) considered here,indicating scattering being an important factor of body wave attenuation in the region.A comparison between Qc and QS shows that QS
引文
郭培兰,姚宏,袁媛.2006.龙滩水库地震危险性分析[J].高原地震,18(4):17--23.
黄玉龙,郑斯华,刘杰,赵兴权,康英.2003.广东地区地震衰减和场地响应的研究[J].地球物理学报,46(1):54--61.
王勤彩,刘杰,郑斯华,陈章立.2005.云南地区与频率有关的P波、S波衰减研究[J].地震学报,27(6):588--597.
姚宏,杨松文,陈斌.2007.Canopy宽带接入系统在龙滩水电工程数字遥测地震台网信道优化设计中的应用[J].地震地磁观测与研究,28(6):63--68.
姚宏,陈鑫,黄树生,龙政强.2008.龙滩水电工程数字遥测地震台网监测能力检验[J].地震地磁观测与研究,29(4):62--66.
Aki K,Chouet B.1975.Origin of coda waves:Source,attenuation,and scattering effects[J].J Geophys Res,80:3322--3342.
Aki K.1980.Attenuation of shear waves in the lithosphere for frequencies from0.05to25Hz[J].Phys Earth PlanetInteri,21(1):56--60.
Atkinson G M,Mereu R F.1992.The shape of ground attenuation curves in Southeastern Canada[J].Bull Seism SocAmer,82(5):2014--2031.
Dinesh K,Sarkar I,Sriram V,Khattri K N.2005.Esti mation of the source parameters of the Hi malaya earthquake ofOctober19,1991,average effective shear wave attenuation parameter and local site effects fromaccelerograms[J].Tectonophysics,407:1--24.
Dinesh K,Sriram V,Khattri K N.2006.Astudy of source parameters,site amplificationfunctions and average effectiveshear wave quality factor Qseff fromanalysis of accelerograms of the1999Chamoli Earthquake,Hi malaya[J].PureAppl Geophys,163:1369--1398.
Gupta S C,Teotia S S,Rai S S,Gautam N.1998.CodaQEsti mates in the Koyna Region,India[J].Pure Appl Geo-phys,153:713--731.
Hoshiba M.1991.Esti mation of scattering andintrinsic attenuationin Japan:Application of multiple lapse ti me windowmethod[C]∥Programme and Abstracts of the Seismological Society of Japan2:209.
Hough S E,Anderson J G.1988.High-frequency spectra observed at Anza,California:I mplications forQstructure[J].Bull Seism Soc Amer,78:672--691.
Johnston D H,Toksoz M N,Ti mur A.1979.Attenuation of seismic wavesin dry and saturated rocks:Ⅱ.Mechanisms[J].Geophysics,44(4):691--711.
Mochizuki S.1982.Attenuationin partially saturated rocks[J].J Geophys Res,87:8598--8604.
Pulli J J,Aki K.1981.Attenuation of seismic waves in the lithosphere:Comparison of active and stable areas,in earth-quakes and earthquake engineering[C]∥Ann Arbor Science Publishers,Ann Arbor,Michigan:129--141.
Pulli J J.1984.Attenuation of coda waves in New England[J].Bull Seism Soc Amer,74(4):1149--1166.
Rocker S W,Tucker B,King J,Hatzfeld D.1982.Esti mates ofQin central Asia as a function of frequency and depthusing the coda of locally recorded earthquakes[J].Bull Seism Soc Amer,72(1):129--149.
Sato H.1980.Q-1value for S wave under the Kanto district in Japan[J].Zisin,33:541--543.
Sato H.1984.Attenuation and envelope formation of three-component seismograms of small local earthquakesin random-ly inhomogeneous lithosphere[J].J Geophys Res,89(B2):1221--1241.
Sharma B,Kumar S.2007.Attenuation of P,S,and coda waves in Koyna region,India[J].J Seismol,11:327--344.
Singh S K,Ordaz M,Dattarayam R S,Guputa H K.1999.Aspectral analysis of21May1997,Jabalpur,India,Earth-quake(MW=5.8)and esti mation of ground motion fromfuture earthquakes in the Indian shield region[J].BullSeism Soc Amer,89(6):1620--1630.
Toksoz M N,Johnston D H,Ti mur A.1979.Attenuation of seismic waves in dry and saturated rocks:Ⅰ.Laboratorymeasurements[J].Geophysics,44(4):671--690.
VanEck T.1988.Attenuation of coda waves in the Dead Sea region[J].Bull Seism Soc Amer,78:770--779.
Winkler K W,Nur A.1982.Seismic attenuation:Effects of pore fluids and frictional sliding[J].Geophysics,47(1):1--15.
Yoshi moto K,Sato H,Ohtake M.1993.Frequency-dependent attenuation of P and S waves in the Kanto area,Japan,based on the coda-normalization method[J].Geophys J Int,114:165--174.
黄玉龙,郑斯华,刘杰,赵兴权,康英.2003.广东地区地震衰减和场地响应的研究[J].地球物理学报,46(1):54--61.
王勤彩,刘杰,郑斯华,陈章立.2005.云南地区与频率有关的P波、S波衰减研究[J].地震学报,27(6):588--597.
姚宏,杨松文,陈斌.2007.Canopy宽带接入系统在龙滩水电工程数字遥测地震台网信道优化设计中的应用[J].地震地磁观测与研究,28(6):63--68.
姚宏,陈鑫,黄树生,龙政强.2008.龙滩水电工程数字遥测地震台网监测能力检验[J].地震地磁观测与研究,29(4):62--66.
Aki K,Chouet B.1975.Origin of coda waves:Source,attenuation,and scattering effects[J].J Geophys Res,80:3322--3342.
Aki K.1980.Attenuation of shear waves in the lithosphere for frequencies from0.05to25Hz[J].Phys Earth PlanetInteri,21(1):56--60.
Atkinson G M,Mereu R F.1992.The shape of ground attenuation curves in Southeastern Canada[J].Bull Seism SocAmer,82(5):2014--2031.
Dinesh K,Sarkar I,Sriram V,Khattri K N.2005.Esti mation of the source parameters of the Hi malaya earthquake ofOctober19,1991,average effective shear wave attenuation parameter and local site effects fromaccelerograms[J].Tectonophysics,407:1--24.
Dinesh K,Sriram V,Khattri K N.2006.Astudy of source parameters,site amplificationfunctions and average effectiveshear wave quality factor Qseff fromanalysis of accelerograms of the1999Chamoli Earthquake,Hi malaya[J].PureAppl Geophys,163:1369--1398.
Gupta S C,Teotia S S,Rai S S,Gautam N.1998.CodaQEsti mates in the Koyna Region,India[J].Pure Appl Geo-phys,153:713--731.
Hoshiba M.1991.Esti mation of scattering andintrinsic attenuationin Japan:Application of multiple lapse ti me windowmethod[C]∥Programme and Abstracts of the Seismological Society of Japan2:209.
Hough S E,Anderson J G.1988.High-frequency spectra observed at Anza,California:I mplications forQstructure[J].Bull Seism Soc Amer,78:672--691.
Johnston D H,Toksoz M N,Ti mur A.1979.Attenuation of seismic wavesin dry and saturated rocks:Ⅱ.Mechanisms[J].Geophysics,44(4):691--711.
Mochizuki S.1982.Attenuationin partially saturated rocks[J].J Geophys Res,87:8598--8604.
Pulli J J,Aki K.1981.Attenuation of seismic waves in the lithosphere:Comparison of active and stable areas,in earth-quakes and earthquake engineering[C]∥Ann Arbor Science Publishers,Ann Arbor,Michigan:129--141.
Pulli J J.1984.Attenuation of coda waves in New England[J].Bull Seism Soc Amer,74(4):1149--1166.
Rocker S W,Tucker B,King J,Hatzfeld D.1982.Esti mates ofQin central Asia as a function of frequency and depthusing the coda of locally recorded earthquakes[J].Bull Seism Soc Amer,72(1):129--149.
Sato H.1980.Q-1value for S wave under the Kanto district in Japan[J].Zisin,33:541--543.
Sato H.1984.Attenuation and envelope formation of three-component seismograms of small local earthquakesin random-ly inhomogeneous lithosphere[J].J Geophys Res,89(B2):1221--1241.
Sharma B,Kumar S.2007.Attenuation of P,S,and coda waves in Koyna region,India[J].J Seismol,11:327--344.
Singh S K,Ordaz M,Dattarayam R S,Guputa H K.1999.Aspectral analysis of21May1997,Jabalpur,India,Earth-quake(MW=5.8)and esti mation of ground motion fromfuture earthquakes in the Indian shield region[J].BullSeism Soc Amer,89(6):1620--1630.
Toksoz M N,Johnston D H,Ti mur A.1979.Attenuation of seismic waves in dry and saturated rocks:Ⅰ.Laboratorymeasurements[J].Geophysics,44(4):671--690.
VanEck T.1988.Attenuation of coda waves in the Dead Sea region[J].Bull Seism Soc Amer,78:770--779.
Winkler K W,Nur A.1982.Seismic attenuation:Effects of pore fluids and frictional sliding[J].Geophysics,47(1):1--15.
Yoshi moto K,Sato H,Ohtake M.1993.Frequency-dependent attenuation of P and S waves in the Kanto area,Japan,based on the coda-normalization method[J].Geophys J Int,114:165--174.
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