用Lg波资料反演场地效应与地震波衰减参数
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摘要
基于谱比法,以台站记录地震波频谱为观测数据,通过扣除仪器响应及几何扩散后同一地震不同台站记录谱比,扣除震源方向性、震源因子的影响,在此基础上,建立数学模型通过联合反演求解场地效应及地震波衰减参数.以浙江省地震台网台站记录的台湾地震数字化地震波资料为基础,使用地震波记录中的Lg波,评估浙江省台网丘陵地带基岩台站场地效应,计算穿越台湾海峡较单一路径Lg波衰减参数.研究使用20次发生于2002—2005年、震级在MS5.0~6.7之间的台湾东北部较小区域地震,参与评估台站16个,地震波记录960条.地震波处理频段为0.5~10.0Hz,每间隔0.2Hz计算一次,对应于垂直、东西及南北分量获得的衰减参数,数据结果分别为:γ(f)=0.00175f0.43485,γ(f)=0.00145f0.48467,γ(f)=0.0021f0.41241.庆元台(QIY)在1.5Hz以上放大效应非常明显,宁波台(NIB)在大部分频率点场地效应最小,参与评估台站场地效应各分向基本相当,未表现出方向性特征.
Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct (two-parameters) determination of Lg wave attenuation and site response from sparse spectral data, which are not affected by radiation factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site response of Zhejiang seismic network stations and measuring Lg wave attenuation. The study is based on 20 earthquakes occurred in northeast of Taiwan with magnitude MS5.0~6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with an frequency interval of 0.2 Hz in the range of 0.5~10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ(f)=0.00175f0.43485, γ(f)=0.00145f0.48467 and γ(f)=0.0021f0.41241, respectively. Site response of QIY station is significant above the frequency of 1.5 Hz, However, site response of NIB station are low for most frequency. The site response are found to be component independent.
Based on spectral ratio method, a joint inversion method was used to obtain parameters of Lg wave attenuation and site response. The inversion method allows simple and direct (two-parameters) determination of Lg wave attenuation and site response from sparse spectral data, which are not affected by radiation factor and different response of same instrument after geometrical spreading. The method was used successfully for estimating site response of Zhejiang seismic network stations and measuring Lg wave attenuation. The study is based on 20 earthquakes occurred in northeast of Taiwan with magnitude MS5.0~6.7 and 960 seismic wave records from 16 stations in Zhejiang area from 2002 to 2005. The parameters of site response and Lg attenuation were calculated with an frequency interval of 0.2 Hz in the range of 0.5~10 Hz. Lg wave attenuation coefficient corresponding to U-D, E-W and N-S components are γ(f)=0.00175f0.43485, γ(f)=0.00145f0.48467 and γ(f)=0.0021f0.41241, respectively. Site response of QIY station is significant above the frequency of 1.5 Hz, However, site response of NIB station are low for most frequency. The site response are found to be component independent.
引文
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Aki K,Richards P G.1980.Quantitative Seismology:Theory and Methods[M].New York:H Freeman.Vol.1&2:1-932.
Borcherdt R D.1970.Effects of local geology on ground motion near San Francisco Bay[J].Bull Seism Soc Amer,60:29-61.
Bonilla L F,Steidl J H,Lindley G T,et al.1997.Site amplification in San Fernando Valley,California:Variability of site effect esti mation using the S-wave,coda and H/V methods[J].Bull Seism Soc Amer,87:710-730.
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Campillo M,Plantet J L,Bouchon M.1985.Frequency-dependence attenuationin the crust beneath central France fromLg waves:Data analysis and numerical madeling[J].Bull Seism Soc Amer,75:1395-1412.
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Herrmann R B,Kijko A.1983.Modeling some empirical vertical component Lg relation[J].Bull Seism Soc Amer,73(1):157-171.
King J L,Tucker B E.1984.Observed variations of earthquakes motion across a sedi ment-filled valley[J].Bull SeismSoc Amer,74:137-152.
Kennett B.1986.Lg waves and structural boundaries[J].Bull Seism Soc Amer,76:1133-1141.
Langston C A.1979.Structure under Mount Rainier,Washington,inferred fromteleseismic body waves[J].J GeophysRes,84:4749-4762.
Moya C A,Aguirre J,Irikura K.2000.Inversion of source parameters and site effects fromstrong ground motion recordsusing genetic algorithms[J].Bull Seism Soc Amer,90(4):977-992.
Murphy J R,Bennett TJ.1982.Adiscri mination analysis of short-period regional seismic data recorded at Tonto ForestObservatory[J].Bull Seism Soc Amer,72:1351-1366.
Nath S K,Biswas N N,Dravinski M,et al.2001.Determination of S-wave site response in Anchorage,Alaska in the1~9Hz frequency band[J].Pure Appl Geophys,159:2673-2698.
Nath S K,Sengupta P,Sengupta S,et al.2000.Site response esti mation using strong motion network:Astep towardsmicrozonation of Sikki m Hi malayas[J].Special Section,79:1316-1326.
Riepl J,Bard P-Y,Hatzfeld D,et al.1998.Detailed evaluation of site-response esti mation methods across and along thesedi mentary valley of Volvi(EURO-SEISTEST)[J].Bull Seism Soc Amer,88:488-502.
Robert J M,Victor E C.1999.Regional waveform propagation in the Arabian Peninsula[J].J Geophys Res.104:20221-20235.
Shi Jinghua,Ki m WY,Paul G R.1998.The corner frequencies and drops of intraplate earthquakes in the NortheasternUnited States[J].Bull Seism Soc Amer,88:531-542.
Tucker B E,King J L,Hatzfeld D.1984.Observations of hard-rock effects[J].Bull Seism Soc Amer,74:121-136.
Xie J,Mitchell B J.1990.Attenuation of multiphase surface waves in the basin and range province:I.Lg and Lg cod[J].Geophys J Int,102:121-137.
陈运泰,吴忠良,王培德,等.2000.数字地震学[M].北京:地震出版社:1-14.
秦嘉政,叶建庆,钱晓东,等.2003.2000年姚安地震的震源参数[J].地球物理学报,46(5):633-641.
Aki K,Richards P G.1980.Quantitative Seismology:Theory and Methods[M].New York:H Freeman.Vol.1&2:1-932.
Borcherdt R D.1970.Effects of local geology on ground motion near San Francisco Bay[J].Bull Seism Soc Amer,60:29-61.
Bonilla L F,Steidl J H,Lindley G T,et al.1997.Site amplification in San Fernando Valley,California:Variability of site effect esti mation using the S-wave,coda and H/V methods[J].Bull Seism Soc Amer,87:710-730.
Brune J N.1970.Tectonic stress and the spectra of seismic shear waves fromearthquake[J].J Geophys Res,75(26):4997-5009.
Brune J N.1971.Correction[J].J Geophys Res,76:5002.
Campillo M,Plantet J L,Bouchon M.1985.Frequency-dependence attenuationin the crust beneath central France fromLg waves:Data analysis and numerical madeling[J].Bull Seism Soc Amer,75:1395-1412.
Chun K-K,Gogdon F W,Richard J K,et al.1987.Anovel technique for measuring Lg attenuation-results fromeasternCanada between1to10[J].Bull Seism Soc Amer,77:398-419.
Garcc姫f D,Singh S K,Herr偄iz M,et al.2004.Inslab earthquakes of Central Mexico:Source spectra and stress drop[J].Bull Seism Soc Amer,94:782-802.
Hartzell S H.1992.Site response esti mation fromearthquake data[J].Bull Seism Soc Amer,82:2308-2327.
Hasegawa HS.1985.Attenuation of Lg waves in the Canada Shield[J].Bull Seism Soc Amer,75:1569-1582.
Herrmann R B,Kijko A.1983.Modeling some empirical vertical component Lg relation[J].Bull Seism Soc Amer,73(1):157-171.
King J L,Tucker B E.1984.Observed variations of earthquakes motion across a sedi ment-filled valley[J].Bull SeismSoc Amer,74:137-152.
Kennett B.1986.Lg waves and structural boundaries[J].Bull Seism Soc Amer,76:1133-1141.
Langston C A.1979.Structure under Mount Rainier,Washington,inferred fromteleseismic body waves[J].J GeophysRes,84:4749-4762.
Moya C A,Aguirre J,Irikura K.2000.Inversion of source parameters and site effects fromstrong ground motion recordsusing genetic algorithms[J].Bull Seism Soc Amer,90(4):977-992.
Murphy J R,Bennett TJ.1982.Adiscri mination analysis of short-period regional seismic data recorded at Tonto ForestObservatory[J].Bull Seism Soc Amer,72:1351-1366.
Nath S K,Biswas N N,Dravinski M,et al.2001.Determination of S-wave site response in Anchorage,Alaska in the1~9Hz frequency band[J].Pure Appl Geophys,159:2673-2698.
Nath S K,Sengupta P,Sengupta S,et al.2000.Site response esti mation using strong motion network:Astep towardsmicrozonation of Sikki m Hi malayas[J].Special Section,79:1316-1326.
Riepl J,Bard P-Y,Hatzfeld D,et al.1998.Detailed evaluation of site-response esti mation methods across and along thesedi mentary valley of Volvi(EURO-SEISTEST)[J].Bull Seism Soc Amer,88:488-502.
Robert J M,Victor E C.1999.Regional waveform propagation in the Arabian Peninsula[J].J Geophys Res.104:20221-20235.
Shi Jinghua,Ki m WY,Paul G R.1998.The corner frequencies and drops of intraplate earthquakes in the NortheasternUnited States[J].Bull Seism Soc Amer,88:531-542.
Tucker B E,King J L,Hatzfeld D.1984.Observations of hard-rock effects[J].Bull Seism Soc Amer,74:121-136.
Xie J,Mitchell B J.1990.Attenuation of multiphase surface waves in the basin and range province:I.Lg and Lg cod[J].Geophys J Int,102:121-137.
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