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用几何扩散函数rγ(r为震源距)中不同指数γ的扩展尾波归一化方法估计了布季地区地壳内P波和S波随频率的衰减。分析基于的是2001年布季(Bhuj)地震(MW7.6)的378个余震测量结果。台网的6个台站在1～24Hz的频率记录下这些余震。在γ固定为1时,对应于频谱衰减的QP-1和QS-1值显示出很强的频率依赖性,并分别用(0.052±0.019)f-(1.1±0.06)和(0.02±0.01)f-(1.0±0.04)表示。在整个频率范围内发现QP-1/QS-1比值大于1。用指数自相关函数表征的任意不均匀性模型,均方根百分比波动ε为6%～8%,相关长度a为0.4～1.2km,频率范围在1～24Hz之间函数ε2/a≈10-2～10-3km可以模拟观测到的衰减特征。这说明,散射模型很好再现了在布季地区获得的QP-1和QS-1与频率有关的特征。
The attenuation of P-wave and S-wave in the crust of the Buji region along the frequency is estimated by using extended coda normalization method with different exponential γ in the geometric diffusion function rγ (r is the source distance). The analysis is based on 378 aftershock measurements of the 2001 Bhuj (MW 7.6) earthquake. Six stations on the network recorded these aftershocks at a frequency of 1 to 24 Hz. The QP-1 and QS-1 values corresponding to the spectral attenuation showed a strong frequency dependence at a fixed γ of 1, with (0.052 ± 0.019) f- (1.1 ± 0.06) and (0.02 ± 0.01) f- (1.0 ± 0.04). The QP-1 / QS-1 ratio was found to be greater than 1 over the entire frequency range. The arbitrary heterogeneity model characterized by exponential autocorrelation function has a root mean square percentage fluctuation ε of 6% -8%, a correlation length a of 0.4-1.2km and a frequency range of 1-24 Hz. The function ε2 / a≈10- 2 ~ 10-3km can simulate the observed attenuation characteristics. This shows that the scattering model reproduces well the frequency-dependent characteristics of QP-1 and QS-1 obtained in the Buji region.