利用面波测定台间衰减系数
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摘要
使用相匹配滤波技术提取基阶面波振型的相位，然后再利用时变滤波进行 振幅谱校正，以此分离出基阶振型面波信号。对合成面波理论地震图的处理结果表 明，该方法可精确地从含高阶（最高阶数为５）的综合地震图中分离出基阶面波，与利 用同一模型合成的基阶面波相比，分离出的基阶面波的振幅谱畸变很小，根据中国数 字化地震台网（ＣＤＳＮ）记录的长周期面波资料，对与震源位于同一大圆弧上的北京。 海拉尔台观测的瑞雷波进行处理，分离出基阶振型信号，然后利用两台的基阶振型信 号进行反褶积得到台间格林函数，由格林函数计算得到台间周期为１３～１４２ ｓ的面 波衰减系数和群速度，所得结果也较为平稳。
A Phase-matched filter is applied to extract phase of fundamental surface wave, and then time-variable filter is used to correct amplitude spectrum in order to isolate fundamental mode signs . By processing of synthetic seismogram of surface wave, it is shown that the method can pre- cisely isolate fundamental surface wave from higher synthetic seismogram including the fifth mode, and deformation of amplitude spectrum is very small comparing with spectrum of funda- mental mode resulted from the same model. Based on long period surface wave recording of the Chinese Digital Seismological Network, the fundamental mode is isolated from Rayleigh wave recorded at Beijing and Hailaer stations which is posisioned on the same great circle path with epi- center, the interstation Green's function is estimated from deconvolution of the fundamental mode signs of the two stations. The interstation group velocity and attenuation in a period of from 13 seconds to 140 seconds are calculated from the Green's function, moreover, the results are signifi- cantly more stable .
A Phase-matched filter is applied to extract phase of fundamental surface wave, and then time-variable filter is used to correct amplitude spectrum in order to isolate fundamental mode signs . By processing of synthetic seismogram of surface wave, it is shown that the method can pre- cisely isolate fundamental surface wave from higher synthetic seismogram including the fifth mode, and deformation of amplitude spectrum is very small comparing with spectrum of funda- mental mode resulted from the same model. Based on long period surface wave recording of the Chinese Digital Seismological Network, the fundamental mode is isolated from Rayleigh wave recorded at Beijing and Hailaer stations which is posisioned on the same great circle path with epi- center, the interstation Green's function is estimated from deconvolution of the fundamental mode signs of the two stations. The interstation group velocity and attenuation in a period of from 13 seconds to 140 seconds are calculated from the Green's function, moreover, the results are signifi- cantly more stable .
引文
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[2] Dziewonski A,Bloch S,Landismar M. A technique for the analysis transient seismic signals[J] . Bull, Siesm. Soc Am. , 1969,59(1):427 ~ 444 .
[3] Dziewonski A, Mills J, Bloch S. Residual dispersion measurement-A new methord surface-wave analysis[J] Bull. Siesm.soc. Am. , 1972, 62(1): 129 - 139 .
[4] Feng C C, Teng T L. An error analysis of frequency-time analysis[J] . Bull. Siesm. Soc. Am., 1982, 73(1): 143~ 155.
[5] 何正勤,叶太兰,孙为国。中朝准地台东部的地壳上地幔QB结构[J]。地震学报,1996,18(1):97-102
[6] Herrin E, Goforth T. Phase-matched filter: application to the study of Rayleigh waves analysis[J] . Bull. Siesm. Soc. Am. ,1977, 67(5) : 427-444.
[7] Cara M. Filtering dispersed wavetrains[J] . Geophys. J ., 1973, 33(1): 65 ~ 80 .
[8] Taylor S R, Toksoz M N. Measurement of interstation phase and group velocities and Q using Wiener filtering[J] . Bull.Siesm. Soc. Am. , 1982 , 72( 1 ) : 73 ~ 91 .
[2] Dziewonski A,Bloch S,Landismar M. A technique for the analysis transient seismic signals[J] . Bull, Siesm. Soc Am. , 1969,59(1):427 ~ 444 .
[3] Dziewonski A, Mills J, Bloch S. Residual dispersion measurement-A new methord surface-wave analysis[J] Bull. Siesm.soc. Am. , 1972, 62(1): 129 - 139 .
[4] Feng C C, Teng T L. An error analysis of frequency-time analysis[J] . Bull. Siesm. Soc. Am., 1982, 73(1): 143~ 155.
[5] 何正勤,叶太兰,孙为国。中朝准地台东部的地壳上地幔QB结构[J]。地震学报,1996,18(1):97-102
[6] Herrin E, Goforth T. Phase-matched filter: application to the study of Rayleigh waves analysis[J] . Bull. Siesm. Soc. Am. ,1977, 67(5) : 427-444.
[7] Cara M. Filtering dispersed wavetrains[J] . Geophys. J ., 1973, 33(1): 65 ~ 80 .
[8] Taylor S R, Toksoz M N. Measurement of interstation phase and group velocities and Q using Wiener filtering[J] . Bull.Siesm. Soc. Am. , 1982 , 72( 1 ) : 73 ~ 91 .
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