利用多道信号测定短周期面波频散

使用适配滤波频时分析技术处理面波信号，获取滤波后的时域包络，并对具有相同群速度的各道信号包络的振幅进行叠加，取叠加所得极大值对应的走时为该频率的群延时，以此来提高群速度的测量精度对P-τ，（相慢度-时间）域的波场进行傅氏变换，然后在P-ω（相慢度-频率）平面叠加多道信号来测定相速度．利用这两种方法处理合成的短周期瑞利波地震图，结果表明：经过振型分离以后，利用基阶振型信号所求出的相速度、群速度曲线更加接近理论频散值．对地震勘探资料进行处理，取得了5-40Hz内的相速度、群速度频散，且曲线较为平滑

DETERMINE SHORT-PERIOD DISPERSION OF SURFACE WAVE FROM MULTICHANNEL SIGNALS

In this paper, the matched-filter frequency-time analysis（MF-FTAN） technique is applied tO analyse surface-wave signals to extract the filtered envelopes in time domain.Then, for each frequency, the amplitudes of signal envelopes for all the channels with same group velocity in turn are stacked, and the travel time corresponding to the maximum stacked-value is concerned as the group delay at the frequency. In this way the group velocity are measured more precisely. On the other hand, by a Fourier transform over wave field in P-τ（phase slowness-time） domain, followed a stack of multichannel signals in P-co （phase slowness-frequency） plane for determing phase velocity. The methods above are used to analyse synthetic Rayleigh seimogram of short Periods, it is concluded, after isolation of mode,that the resulted dispersion of group and phase velocity from the fundamental mode signals are also closer to theoretical ones than those from other methods. The phase and group velocity dispersions in a range of 5-40Hz by analysis of seismic exploration recording in the same way are smoother as well.