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本文以1985年4月18日云南禄劝地震为例,用不同拟合法探讨了地震波卓越频率衰减系数α值在大地震前后的特征变化。结果发现:单台单震拟合的α值有趋势变化,但误差范围较大。而单台三震拟合的α值有明显的特征变化,并且误差范围显著减小。同时单震双台拟合的α值的变化特征也相当突出。它们均在禄劝6.1级地震前约2年,α值开始下降并有持续低值阶段。平均下降幅度约为正常值的40％到60％,最大下降幅度约60％到80％。这表明,经过适当处理,是可以根据频率衰减系数的变化来预报地震的。
Taking the Luquan earthquake in Yunnan Province on April 18, 1985 as an example, this paper uses different fitting methods to investigate the characteristic changes of the excellent frequency attenuation coefficient α of seismic waves before and after a large earthquake. The results show that the α value of a single monopatch fitting has a trend change, but the error range is larger. However, the α value of a single three-shot fitting has obvious characteristic changes, and the error range is significantly reduced. At the same time, the changing characteristics of the α value of the single-and dual-station fitting are also quite prominent. Both of them were about 2 years before Luquan 6.1 earthquake, the α value began to decline and there was a sustained low value stage. The average decline of about 40% to 60% of normal, the maximum decline of about 60% to 80%. This shows that, after proper treatment, the earthquake can be predicted based on the change of the frequency attenuation coefficient.