由Lg波振幅谱估算地震矩及Lg波Q值
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摘要
采用一种多事件 多台站的Lg波谱反演方法 ,同时反演若干新疆伽师地震的地震矩M0 、源拐角频率fc 及从这些地震的震中到 8个中亚地震台站 (WMQ ,AAK ,TLG ,MAKZ ,KUR ,VOS ,ZRN和CHK)的传播路径所对应的视QLg模型参数 .反演得到的地震矩与质心矩反演结果具有较好的相关性 ,而且在利用区域震SV波的平均源辐射因子的典型值来进行校正后 ,二者在数值上也基本一致 .同时 ,反演得到的地震矩与面波震级也具有很好的相关性 .反演得到的视Q0Lg(1Hz时的QLg)与路径的构造特征相符合 .其中 ,AAK ,TLG和MAKZ 3个台站对应的传播路径 ,绝大部分在地形起伏强烈、地震活动性强的天山地区对应的Q0Lg较小 ,分别为 3 5 1± 87,3 49± 86和 3 0 0± 2 7.KUR ,VOS ,ZRN和CHK 4个台站的传播路径大部分在比较稳定的哈萨克地台 ,对应的Q0Lg较大 ,分别为 5 5 3± 72 ,5 69± 5 8,5 5 0± 5 7和 60 3± 65 ;而WMQ对应的传播路径基本上沿塔里木盆地及天山边缘地带 ,沿传播路径的地形和地壳厚度的变化 ,不如沿至MAKZ台的传播路径的变化那么剧烈 ,因此 ,其Q0Lg也比到MAKZ对应的传播路径的Q0Lg大 ,反演结果为 462± 5 6.
A multi-event and multi-station inverse method is presented in the paper to simultaneously estimate the seismic moments (M 0) and source corner frequencies (f c) of several Jiashi (Xinjiang, China) earthquakes, as well as the apparent Q Lg models for the paths from Jiashi to eight seismic stations (WMQ, AAK, TLG, MAKZ, KUR, VOS, ZRN and CHK) in Central Asia. The resulted seismic moments correlate well with the M 0 values obtained by Harvard University using the centroid moment tensor (CMT) inversion and the surface-wave magnitudes as well. After the correction by a typical value of average radiation coefficient for regional SV waves, the M 0 values from Lg spectral inversion are still close to the corresponding values obtained from CMT inversion. The obtained apparent Q 0Lg values (Q Lg at 1 Hz) are consistent with the tectonic features of corresponding propagation paths. The Q 0Lg values are 351±87, 349±86 and 300±27 for the paths from Jiashi to AAK, TLG and MAKZ, respectively. They are smaller than Q 0Lg values for the paths to KUR, VOS, ZRN and CHK, which are 553±72, 569±58, 550±57 and 603±65, respectively. These results agree with the condition that the paths to AAK, TLG and MAKZ mainly propagate through the mountainous Tianshan area where relatively strong seismic activities and large variations of topography are exhibited, while the paths to KUR, VOS, ZRN and CHK mainly propagate through the stable area of Kazak platform. The Q 0Lg value for the path to WMQ is 462±56. This is also in agreement with the condition that the path to WMQ is basically along the border area between Tianshan Mountain and Tarim Basin, and along this path the variations of topography and crustal thickness are moderate in comparison with that along the path to MAKZ.
A multi-event and multi-station inverse method is presented in the paper to simultaneously estimate the seismic moments (M 0) and source corner frequencies (f c) of several Jiashi (Xinjiang, China) earthquakes, as well as the apparent Q Lg models for the paths from Jiashi to eight seismic stations (WMQ, AAK, TLG, MAKZ, KUR, VOS, ZRN and CHK) in Central Asia. The resulted seismic moments correlate well with the M 0 values obtained by Harvard University using the centroid moment tensor (CMT) inversion and the surface-wave magnitudes as well. After the correction by a typical value of average radiation coefficient for regional SV waves, the M 0 values from Lg spectral inversion are still close to the corresponding values obtained from CMT inversion. The obtained apparent Q 0Lg values (Q Lg at 1 Hz) are consistent with the tectonic features of corresponding propagation paths. The Q 0Lg values are 351±87, 349±86 and 300±27 for the paths from Jiashi to AAK, TLG and MAKZ, respectively. They are smaller than Q 0Lg values for the paths to KUR, VOS, ZRN and CHK, which are 553±72, 569±58, 550±57 and 603±65, respectively. These results agree with the condition that the paths to AAK, TLG and MAKZ mainly propagate through the mountainous Tianshan area where relatively strong seismic activities and large variations of topography are exhibited, while the paths to KUR, VOS, ZRN and CHK mainly propagate through the stable area of Kazak platform. The Q 0Lg value for the path to WMQ is 462±56. This is also in agreement with the condition that the path to WMQ is basically along the border area between Tianshan Mountain and Tarim Basin, and along this path the variations of topography and crustal thickness are moderate in comparison with that along the path to MAKZ.
引文
葛焕称,倪岳伟,李敬华,等.1992.中国大陆区域Lg震级标度[J].地震学报,14(1):51～61
AlEqabiGI,KopperKD ,WysessionME .2001.SourcecharacterizationofNevadaTestSiteexplosionsandWesternUSearthquakesusingLgwavs:implicationsforregionalsource[J].BullSeismSocAmer,91(1):140～153
BooreDM ,BoatwrightJ.1984.Averagebody waveradiationcoefficients[J].BullSeismSocAmer,74(5):1615～1621
BouchonM .1982.Thecompletesynthesisofseismiccrustalphasesatregionaldistances[J].JGeophysRes,87(B3):1735～1741
CongL ,XieJ,MitchellBJ .1996.ExcitationandpropagationofLgfromearthquakesinCentralAsiawithimplicationsonexplosion/earthquakediscrimination[J].JGeophysRes,101(B12):27779～27789
HerrmannRB ,KijkoA .1983.ModelingsomeempiricalverticalcomponentLgrelations[J].BullSeismSocAmer,73(1):157～171
IsraelssonH .1994.Analysisofhistoricalseismograms—rootmeansquareLgmagnitudes,yieldsanddepthsofexplosionsattheSemi palatinskTestRange[J].GeophysJInt,117(3):591～609
KnopoffL ,SchwabF ,KauselE .1973.InterpretationofLg[J].GeophysicJRastrSoc,33(4):389～404
NuttliOW .1973.SeismicwaveattenuationandmagnituderelationforeasternNorthAmerica[J].JGeophysRes,78(5):876～885
NuttliOW .1986.YieldestimatesofNevadaTestSiteexplosionsobtainedfromseismicLgwaves[J].JGeophysRes,91(B2):2137～2151
PattonHJ.1988.ApplicationofNuttli’smethodtoestimateyieldofNevadaTestSiteexplosionsrecordedonLawrenceLivermoreLabo ratory′sdigitalseismicsystem[J].BullSeismSocAmer,78(6):1759～1772
SerenoTJ,BrattSR ,BacheTC .1988.SimultaneousinversionofregionalwavespectraforattenuationandseismicmomentinScandi navia[J].JGeophysRes,93(B3):2019～2035
StreetRL ,HerrmannRB ,NuttliOW .1975.SpectralcharacteristicsoftheLgwavegeneratedbycentralUnitedStatesearthquakes[J].GeophysJRastrSoc,41(1):51～63
XieJiakang.1993.SimultaneousinversionforsourcespectrumandpathQusingLgwithapplicationtothreeSemipaltinskexplosions[J].BullSeismSocAmer,83(6):1547～1562
XieJ ,CongL ,MitchellBJ .1996.SpectralcharacteristicsoftheexcitationandpropagationofLgfromundergroundnuclearexplosionsincentralAsia[J].JGeophysRes,101(B3):5813～5822
XieJiakang.1998.SpectralinversionofLgfromearthquakes:Amodifiedmethodwithapplicationto1995,westernTexasearthquakessequence[J].BullSeismSocAmer,88(6):1525～1537
AlEqabiGI,KopperKD ,WysessionME .2001.SourcecharacterizationofNevadaTestSiteexplosionsandWesternUSearthquakesusingLgwavs:implicationsforregionalsource[J].BullSeismSocAmer,91(1):140～153
BooreDM ,BoatwrightJ.1984.Averagebody waveradiationcoefficients[J].BullSeismSocAmer,74(5):1615～1621
BouchonM .1982.Thecompletesynthesisofseismiccrustalphasesatregionaldistances[J].JGeophysRes,87(B3):1735～1741
CongL ,XieJ,MitchellBJ .1996.ExcitationandpropagationofLgfromearthquakesinCentralAsiawithimplicationsonexplosion/earthquakediscrimination[J].JGeophysRes,101(B12):27779～27789
HerrmannRB ,KijkoA .1983.ModelingsomeempiricalverticalcomponentLgrelations[J].BullSeismSocAmer,73(1):157～171
IsraelssonH .1994.Analysisofhistoricalseismograms—rootmeansquareLgmagnitudes,yieldsanddepthsofexplosionsattheSemi palatinskTestRange[J].GeophysJInt,117(3):591～609
KnopoffL ,SchwabF ,KauselE .1973.InterpretationofLg[J].GeophysicJRastrSoc,33(4):389～404
NuttliOW .1973.SeismicwaveattenuationandmagnituderelationforeasternNorthAmerica[J].JGeophysRes,78(5):876～885
NuttliOW .1986.YieldestimatesofNevadaTestSiteexplosionsobtainedfromseismicLgwaves[J].JGeophysRes,91(B2):2137～2151
PattonHJ.1988.ApplicationofNuttli’smethodtoestimateyieldofNevadaTestSiteexplosionsrecordedonLawrenceLivermoreLabo ratory′sdigitalseismicsystem[J].BullSeismSocAmer,78(6):1759～1772
SerenoTJ,BrattSR ,BacheTC .1988.SimultaneousinversionofregionalwavespectraforattenuationandseismicmomentinScandi navia[J].JGeophysRes,93(B3):2019～2035
StreetRL ,HerrmannRB ,NuttliOW .1975.SpectralcharacteristicsoftheLgwavegeneratedbycentralUnitedStatesearthquakes[J].GeophysJRastrSoc,41(1):51～63
XieJiakang.1993.SimultaneousinversionforsourcespectrumandpathQusingLgwithapplicationtothreeSemipaltinskexplosions[J].BullSeismSocAmer,83(6):1547～1562
XieJ ,CongL ,MitchellBJ .1996.SpectralcharacteristicsoftheexcitationandpropagationofLgfromundergroundnuclearexplosionsincentralAsia[J].JGeophysRes,101(B3):5813～5822
XieJiakang.1998.SpectralinversionofLgfromearthquakes:Amodifiedmethodwithapplicationto1995,westernTexasearthquakessequence[J].BullSeismSocAmer,88(6):1525～1537
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