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本文讨论了四种估计地震烈度衰减的方法以及它们的优缺点。烈度按长轴和短轴方向分别求衰减系数的方法似已过时,不足以造用。Howell的方法缺乏明确的物理图象,并且不能把求得的烈度衰减系数和介质性质联系起来,它几乎是一个纯经验公式。Evernd-en的方法把震源等效成一个埋在地下的线轴射源,地震波以R~(-k)随距离衰减,物理图象比较明确,但仍然不能使每个地震的k值和一个地区的介质的Q值联系起来。Nuttli 的方法,假定不尽合理,但有其合理的内核,能求得一个地区的Q_0值和每个地震的体波震级。作者用Nuttli的方法,计算了106个中国地震的Q_0值和体波震级m_b。并把中国粗略地划分出九个地区,求出了每个地区的Q_0值。结果表明,西南地区和台湾Q_0值最低,为150;华北和华南Q_0值最高,约为500;其余地区居中。这个结果与Evernden,陈培善等人,以及赵晓敏等人对烈度资料用不同的分析方法得到的结果定性讲是一致的。陈培善用地壳尾波资料得到云南地区的Q_0≈180,北京地区的Q_0≈400,这与本文用地震烈度资料估计的Q_0值相当吻合。
This article discusses four methods for estimating seismic intensity attenuation and their advantages and disadvantages. Intensity according to the long axis and short axis direction of the attenuation coefficient of the method seems outdated, not enough to make. Howell’s method lacks a clear physical image and can not relate the calculated intensity attenuation coefficient to the nature of the medium, which is almost a pure empirical formula. In the method of Evernd-en, the source is equivalent to a buried axial source. The seismic wave attenuates with distance R ~ (-k) and the physical image is clear. However, it still can not make the k value of each earthquake and a region Of the media Q value linked. Nuttli’s method, assumed not to be reasonable, has its reasonable kernel to derive the Q_0 value for a region and the body-wave magnitude for each earthquake. Using the method of Nuttli, the authors calculated the Q_0 value of 106 earthquakes in China and the body-wave magnitude m_b. And China roughly divided nine regions, calculated the value of each region Q_0. The results showed that the value of Q_0 was the lowest in Southwest China and Taiwan, and the value of Q_0 was the highest in North China and South China, which was about 500; the rest were in the middle. This result is qualitatively consistent with the results obtained by Evernden, Chen Peishan et al., And Zhao Xiaomin et al. On the intensity data using different analytical methods. Chen Peishan obtained the Q_0≈180 in Yunnan and Q_0≈400 in Beijing using the crustal coda data, which is in good agreement with the Q_0 estimated by the seismic intensity data in this paper.