华东地区小震P波震源参数特征初探
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摘要
选取上海数字化地震台网(台阵)记录到的2001~2004年华东地区发生80次记录较好的小地震。扣除仪器响应、介质响应等,反演单台记录垂直向纵波(P波)震源谱,根据布龙位错模型,计算每个地震单台拐角频率、地震矩、零频谱值、震源破裂半径、应力降等参数,求出每个地震的震源参数的平均值及其均方差,给出了该区小震震源的范围,研究了各参数之间的关系以及各参数与震级(ML)之间的关系。结果表明,华东地区小地震(ML0.8~4.4)拐角频率与震级的关系可以用三次曲线拟合,亦可以将ML2.5~3.0做为分界点用直线分段拟合,后者效果更好;零频谱值的对数与震级关系可以用直线拟合,也可以用二次曲线拟合,效果好于直线拟合;地震矩与震级的关系与零频谱值相似;震源破裂半径的对数与震级的关系可用直线、二次曲线以及三次曲线拟合,3者效果相近;应力降与震级、地震矩以及震源破裂半径之间不存在明显的依赖关系。
In The paper, 80 minor earthquakes well recorded by Shanghai Digital Seismic Network(Array) in East China from 2001 to 2004 were chosen. Eliminating the instrumental response and the medium response and so on, vertical spectrum of P wave recorded at each seismic station was inversed, and parameters of each earthquake such as corner frequency, seismic moment, zero spectrum, rupture radius of seismic source, stress drop and so on were calculated by means of Brune model, then the mean value and mean square error of source parameters each earthquake were obtained. As the same time, the range of minor earthquakes is obtained and the relationship among source parameters, the relationship of ML and each source parameter were analyzed. The result shows that the relationship between magnitude and corner frequency could be fitted by cubic curved, and straight line, respectively, the minor earthquakes of ML 0.8～4.4 and ML 2.5～3.0 in East China, but the later is effective. And not only the relationship between the logarithm of zero spectrum and magnitude can be fitted by straight line but also quadratic curve, but the later is more effective. Beside, rupture radius of seismic source can be fitted by quadratic curve, by cubic curve and by straight line, but three of them have the close effect. Finally, there is no apparent relationship among stress drop and magnitude、seismic moment、rupture radius of seismic source.
In The paper, 80 minor earthquakes well recorded by Shanghai Digital Seismic Network(Array) in East China from 2001 to 2004 were chosen. Eliminating the instrumental response and the medium response and so on, vertical spectrum of P wave recorded at each seismic station was inversed, and parameters of each earthquake such as corner frequency, seismic moment, zero spectrum, rupture radius of seismic source, stress drop and so on were calculated by means of Brune model, then the mean value and mean square error of source parameters each earthquake were obtained. As the same time, the range of minor earthquakes is obtained and the relationship among source parameters, the relationship of ML and each source parameter were analyzed. The result shows that the relationship between magnitude and corner frequency could be fitted by cubic curved, and straight line, respectively, the minor earthquakes of ML 0.8～4.4 and ML 2.5～3.0 in East China, but the later is effective. And not only the relationship between the logarithm of zero spectrum and magnitude can be fitted by straight line but also quadratic curve, but the later is more effective. Beside, rupture radius of seismic source can be fitted by quadratic curve, by cubic curve and by straight line, but three of them have the close effect. Finally, there is no apparent relationship among stress drop and magnitude、seismic moment、rupture radius of seismic source.
引文
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郑治真.1979.波谱分析基础[M].北京:地震出版社,294~258
Atkinson G Mand Boore D M.1998.Evaluation of modeles for earthquake source spectra in eastern North America[J].BSSA,88,917~934
Beresnev I A.2001.What we can and cannot learn about earthquake sources fromthe spectra of seismic waves[J].BSSA,91(2):397~400
Bindi D,Daniele S,Paolo Aand Marco C.2001.Source Parameters Esti mated fromthe Aftershocks of the1997Umbria-Marche(Italy)Seismic Sequence[J].BSSA,91(3):448~455
Castro Raul R,Luca Trojani,Giancarlo Monachesi,Marco Mucciarelli and Marco Cattaneo.2000.The spectral decay parameterKinthe region of Umbria-Marche,Italy[J].JGR,105(B10):23811~23823
Jin A,Moya C Aand Ando M.2000.Si multaneous determination of site responses and source parameters of small earthquakes alongthe Atotsugawa Fault Zone,Central Japan[J].BSSA,90(6):1430~1445
Jones L Eand Hel mberger D V.1998.Earthquake source parameters and fault kinematics in the eastern California shear zone[J].BSSA,88(6):1337~1352
Moya A,Aguirre J and Irikura K.2000.Inversion of source parameters and site effects fromstrong ground-motion records usinggenetic algorithms[J].BSSA,90(4):977~992
康英,郑斯华等.2004.中小地震震源参数的求解及其相似关系[J].华南地震,24(2):11~21
刘杰,郑斯华等.2003.利用遗传算法反演弹性衰减系数、震源参数和场地响应[J].地震学报,25(2):211~218
刘瑞丰.2003.震级,地震参数——数字地震学在地震预报中的应用[M].见中国地震局监测预报司编,北京:地震出版社,7~13
沈小七,刘杰等.2005.安徽地区地震波衰减、场地响应及震源新参数的测定[J].地震地磁观测与研究,26(3):1~10
郑治真.1979.波谱分析基础[M].北京:地震出版社,294~258
Atkinson G Mand Boore D M.1998.Evaluation of modeles for earthquake source spectra in eastern North America[J].BSSA,88,917~934
Beresnev I A.2001.What we can and cannot learn about earthquake sources fromthe spectra of seismic waves[J].BSSA,91(2):397~400
Bindi D,Daniele S,Paolo Aand Marco C.2001.Source Parameters Esti mated fromthe Aftershocks of the1997Umbria-Marche(Italy)Seismic Sequence[J].BSSA,91(3):448~455
Castro Raul R,Luca Trojani,Giancarlo Monachesi,Marco Mucciarelli and Marco Cattaneo.2000.The spectral decay parameterKinthe region of Umbria-Marche,Italy[J].JGR,105(B10):23811~23823
Jin A,Moya C Aand Ando M.2000.Si multaneous determination of site responses and source parameters of small earthquakes alongthe Atotsugawa Fault Zone,Central Japan[J].BSSA,90(6):1430~1445
Jones L Eand Hel mberger D V.1998.Earthquake source parameters and fault kinematics in the eastern California shear zone[J].BSSA,88(6):1337~1352
Moya A,Aguirre J and Irikura K.2000.Inversion of source parameters and site effects fromstrong ground-motion records usinggenetic algorithms[J].BSSA,90(4):977~992
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