| 用尾波的强度和衰减估算北京地区 S 波的平均自由程h |
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| 引用本文： | 高龙生,华正兴,李瑞瑄.用尾波的强度和衰减估算北京地区 S 波的平均自由程h[J].地震学报,1987,9(4):347-363. |
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| 作者姓名： | 高龙生 华正兴 李瑞瑄 |
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| 作者单位： | 国家地震局地球物理研究所 |
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| 基金项目： | 地震学联合科学基金会的部分资助 |
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| 摘 要： | Aki 提出的单次散射模型由于它的简单而显得很实用.作为单次散射模型的改进,本文表明应用多次散射模型也可给出一个简单可行的办法来估算一定地区地下介质的不均匀性.本文分别用尾波的强度和衰减求出与散射有关的 Q 因子.可以看到,尽管单次散射模型和多次散射模型两者给出了十分接近的结果,但后者显得更加合理并有其自相一致性.本文认为,无论运用哪个简化了的模型,方程(InA=1——Int——b1t 或 InA=2——0.5lnt——b2t)中的对数项是不可忽略的.本文应用北京地区地震台网资料,求出了频率在1Hz 左右北京地区 S 波的平均自由程,结果见表2.
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| 关 键 词： | 地震波 尾波 衰减 Q 值 散射 |
ESTIMATION OF MEAN FREE PATH OF S-WAVES UNDER BEIJING AREA BY MEANS OF BOTH INTENSITY AND DECAY OF CODAS |
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| Affiliation: | Institute of Geophysics, State Seismological Bureau |
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| Abstract: | The single back scattering model proposed by Aki is convenient due to its simplicity. This paper shows that the multiple scattering model whtch is an imporovement upon .Aki's model also gives a very simple and successful approach to estimate the heterogeneities under a certain area. Both the intensity and the decay of codas were used to find the Q-tactor related to scattering. It is noted that although both the single scattering model and the multiple scattering model give quite close results, the results from the latter are more reasonable and self-consistent. This paper also suggests that whichever simplified model is used, the logarithmic term in its equation is not negligible. As an example, seismograms of local erthoquakes recorded at the Beijing Regional Seismological Network were used and the mean free path of S-vvave under the Beijing area was obtained at frequencies around 1 Hz, shown in Table 2. |
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