澜沧-耿马地震后尾波衰减的区域特征
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摘要: 本文在地方震尾波单次散射模式的基础上,用澜沧-耿马 Ms=7.6和7.2两次强震后,震中附近4个短周期台站记录的余震尾波观测资料,采用一种新的联合测定法估算了澜沧-耿马地区尾波振幅衰减率和Qc值.结果表明,在所划分的南区和北区内,尾波振幅衰减率发生了明显的区域差异,表现为南区衰减快(Qc=114),北区衰减慢(Qc=231),并讨论了这种空间差异的原因.本文的结果还给出,尾波源因子 A0(f)与地震矩和震级有较好的线性关系,用地震定标律导出:lgM0=lgA0(f)+17.6,MD+0.67lgA0(f)+1.21,lgM0+1.5MD+15.79.其次,用尾波单次散射模式和多重散射模式计算了振幅衰减率s 和m,结果给出两种模式结果之比m/s 在1.20-1.50之间.用区分固有 Q 和散射 Q 的关系求出了南区和北区的 S 波散射平均自由程 L 分别为54km和122km,由此证实了低 Q 地区对应强散射.
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[1] 高龙生、华正兴、李瑞喧, 1987.用尾波的强度和衰减估算北京地区S波的平均自由程.地震学报,9, 347——363.
[2] 秦嘉政、阚荣举,1986.用i波估算昆明及其周围地区的Q值和地震矩.地球物理学报,29, 145——156.
[3] 晏风桐、莫宏进,1984. 1982年剑川地震的尾波.地震研究,7, 505——510
[4] 秦嘉政、李宁、胡克坚,1987. 1985年云南禄劝地震余震尾波Q值的某些研究.地震学报,9, 239——252
[5] 秦嘉政,1989.云南地区短周期波区域Q值与地震烈度衰减的关系.云贵地区地震危险性研究文集, 253——260.云南科技出版社,昆明.
[6] Aki, K., 1969. Analysis of the seismic coda of local earthquakes as scattered waves. J. Ciropdryc, Res. 74, 61 615——631.
[7] Aki, K. and Chouet, B., 1975. Origin of coda waves: source, attenuation, and scattering edects.J. Geophhs.Res, 80,3322——3342.
[8] Biswas, N.N.and Aki, K.,1984. Characteristics of coda waves: central and southcentral Alaska. Bull. Seism. Soc.,Amer, 74, 493——507
[9] Chen, P. S.,Nuttli, O. W.,Yc,W.H.and Qin,J.Z.,1984. Estunates of short——period Q values and seismic moments from coda waves for eathquakes of the Beijng, and Yunnan regions of China. Bull. Seinn. Soc. Arner, 74, 1189——1207.
[10] Dainty, A, M.and Toksoz, M.N 1981. Seismic codas on the earth and the moon:a comparison.Phys.Eearth.Planet:Interiors, 26, 250——260.
[11] Hough, S. E. and Anderson, J, G.. 1988. High——frequency spectra observed at Anza, Califortnia: implications for Q structure. Bull. Seism. Soc.Amer.,78, 692——707.
[12] Hettmann, R. B.,1980. Qestimates using the coda oflocal earthquakes, Bull. Seism Soc.Amer.,70, 447——468.
[13] Peng, J. Y.,Aki, K.,Chouet, B.,et al. 1987. Temporal change in coda Q associated with the Round Valley, California, eathquakc of November 23,1984. J. Geo,J. Geophys. Res. 92, 3507——3526.
[14] Pulli, J. J.,1984.Attenuation of coda waves in New England. Bull. Seism. Soc. Anrer,74, 1149——1166.
[15] Sato, H, 1984. Attenuation and envelope formation of three——component seismograms of small local earthquakes in randomly inhomogeneous lithospere. J. Geophys,Res.,89, 1221——1241.
[16] Singh, S. and Herrniann, R. B.,1983. Regionalization of crustal coda Q in the continental United States. J. Geophys. Res, 88, 527——538.[1] 高龙生、华正兴、李瑞喧, 1987.用尾波的强度和衰减估算北京地区S波的平均自由程.地震学报,9, 347——363.
[2] 秦嘉政、阚荣举,1986.用i波估算昆明及其周围地区的Q值和地震矩.地球物理学报,29, 145——156.
[3] 晏风桐、莫宏进,1984. 1982年剑川地震的尾波.地震研究,7, 505——510
[4] 秦嘉政、李宁、胡克坚,1987. 1985年云南禄劝地震余震尾波Q值的某些研究.地震学报,9, 239——252
[5] 秦嘉政,1989.云南地区短周期波区域Q值与地震烈度衰减的关系.云贵地区地震危险性研究文集, 253——260.云南科技出版社,昆明.
[6] Aki, K., 1969. Analysis of the seismic coda of local earthquakes as scattered waves. J. Ciropdryc, Res. 74, 61 615——631.
[7] Aki, K. and Chouet, B., 1975. Origin of coda waves: source, attenuation, and scattering edects.J. Geophhs.Res, 80,3322——3342.
[8] Biswas, N.N.and Aki, K.,1984. Characteristics of coda waves: central and southcentral Alaska. Bull. Seism. Soc.,Amer, 74, 493——507
[9] Chen, P. S.,Nuttli, O. W.,Yc,W.H.and Qin,J.Z.,1984. Estunates of short——period Q values and seismic moments from coda waves for eathquakes of the Beijng, and Yunnan regions of China. Bull. Seinn. Soc. Arner, 74, 1189——1207.
[10] Dainty, A, M.and Toksoz, M.N 1981. Seismic codas on the earth and the moon:a comparison.Phys.Eearth.Planet:Interiors, 26, 250——260.
[11] Hough, S. E. and Anderson, J, G.. 1988. High——frequency spectra observed at Anza, Califortnia: implications for Q structure. Bull. Seism. Soc.Amer.,78, 692——707.
[12] Hettmann, R. B.,1980. Qestimates using the coda oflocal earthquakes, Bull. Seism Soc.Amer.,70, 447——468.
[13] Peng, J. Y.,Aki, K.,Chouet, B.,et al. 1987. Temporal change in coda Q associated with the Round Valley, California, eathquakc of November 23,1984. J. Geo,J. Geophys. Res. 92, 3507——3526.
[14] Pulli, J. J.,1984.Attenuation of coda waves in New England. Bull. Seism. Soc. Anrer,74, 1149——1166.
[15] Sato, H, 1984. Attenuation and envelope formation of three——component seismograms of small local earthquakes in randomly inhomogeneous lithospere. J. Geophys,Res.,89, 1221——1241.
[16] Singh, S. and Herrniann, R. B.,1983. Regionalization of crustal coda Q in the continental United States. J. Geophys. Res, 88, 527——538.
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