灵武地震尾波频率特性及介质参数的测定
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摘要: 本文提出了一种利用地方震尾波测定地壳介质相关长度和 Q 值的方法.该方法基于全面考虑了震源谱、介质散射特性和仪器响应诸因素对尾波优势频率的影响,得到公式t*=2/[1/f(1+12f2+1/f(1+22f2-1/f+1/2 d/df In I(f)] 其中t*=t/Q,f 为尾波优势频率,1,2分别为由介质相关长度和震源拐角频率确定的参数,I(f)为仪器响应.当给定震源参数(2)时,可通过对已测尾波 f-t 曲线反演计算求解相关长度和Q 值,应用这一方法,我们处理了灵武地区1982至1989年期间40余次地震的尾波资料.测定了相关长度和 Q 值,并对中强地震前后介质相关长度的时间变化作了初步研究.结果表明,震前介质相关长度表现出减小的迹象.
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[1] 杨明芝、董卫国, 1985利用地方震出格记录尾波测定宁夏北部及邻区Q值.西北地震学报,7. 2, 23——30.
[2] Aki, K.,1969. Analysis of the seismic coda oflocal earthquakes as scattered waves..J. Geophys. Res.74, 3332——3342.
[3] Aki. K., 1980. Scattering and attenuation of shear waves in the lithosphere. J. Geophys. Res. 85, 811, 6496——6502.
[4] Chen, P, S.,Nuttli, O. W.,Ye, W. H. and Qin, J. Z.,1984. Estimates of short——period Q values and seismic momenu from coda waves for earthquakes of the Beipng and Yunnan regions of China. Bull. Seism. Soc. Anger.74,44——53.
[5] Frankel, A. and Kanamori, H., 1983. Determination of rupture duration and strecs drop for earthquakes in southern California. Bull. Seism, Soc. Arraer. 73, 1527——1551.
[6] Herrmann. It. B.,1980. Q Estimates using the coda of local earthquakes. Bull. Seisrra. Soc. Amer.70, 447——468.
[7] Herrav, M. and Espionosa. A. F.,1987. Coda waves:A review. PAGEDPH, 125, 540——554.
[8] Wu, R. S. and Aki, K.,1985. Elastic waves scattering by a random medium and the small——scale inhomogeneities in the lithosphere. J., Geophys. Reo.,90, B 12,10261——10273.[1] 杨明芝、董卫国, 1985利用地方震出格记录尾波测定宁夏北部及邻区Q值.西北地震学报,7. 2, 23——30.
[2] Aki, K.,1969. Analysis of the seismic coda oflocal earthquakes as scattered waves..J. Geophys. Res.74, 3332——3342.
[3] Aki. K., 1980. Scattering and attenuation of shear waves in the lithosphere. J. Geophys. Res. 85, 811, 6496——6502.
[4] Chen, P, S.,Nuttli, O. W.,Ye, W. H. and Qin, J. Z.,1984. Estimates of short——period Q values and seismic momenu from coda waves for earthquakes of the Beipng and Yunnan regions of China. Bull. Seism. Soc. Anger.74,44——53.
[5] Frankel, A. and Kanamori, H., 1983. Determination of rupture duration and strecs drop for earthquakes in southern California. Bull. Seism, Soc. Arraer. 73, 1527——1551.
[6] Herrmann. It. B.,1980. Q Estimates using the coda of local earthquakes. Bull. Seisrra. Soc. Amer.70, 447——468.
[7] Herrav, M. and Espionosa. A. F.,1987. Coda waves:A review. PAGEDPH, 125, 540——554.
[8] Wu, R. S. and Aki, K.,1985. Elastic waves scattering by a random medium and the small——scale inhomogeneities in the lithosphere. J., Geophys. Reo.,90, B 12,10261——10273.
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