用最大熵谱法分析玉门地震序列的频谱变化

Analysis on the Spectrum Variation of Yumen Earthquake Sequence by Using Maximum-entropy Method

采用Burg最大熵谱分析方法对玉门地震序列进行了频谱分析计算。结果显示：当主震发生时，频谱主频向高频方向变化，当整个序列接近尾声时，频率逐渐恢复。这个结果可解释为，随着应力的积累，孕震区介质部分裂隙闭合，挤出裂隙水，密度相对增大，品质因数提高，高频成分的衰减降低，使频谱的主频率移向高频。

In this paper the spectrum of Yumen earthquake sequence was calculated and analyzed by using the maximum-entropy method of Burg. The results showed that the dominant frequen- cies changed in direction to high frequencies with the coming of main shock, and the dominant frequencies gradually restored with the ending of sequence. This phenomenon could be under- stood as： with the accumulation of stress, some crannies across the earthquake-preparation zone were closed, then fluid in the crannies was pushed out, and density of the medium became rela- tively high, which made quality factor of the medium increase and attenuation of high-frequency components reduce so that dominant frequencies became higher.