Morlet变换在超宽频带地震仪记录的汶川震前数据处理中的应用

Application of Morlet Transform in Pre-Earthquake Data Processing of Wenchuan Earthquake Recorded by Ultra Broadband Seismograph

介绍了Morlet小波变换的基本原理和特点。以汶川地震为例,选取2008-05-01~05-12的地震计垂直向连续波形数据,使用Morlet小波变换得到时频谱。分析时频图发现,在汶川地震发生前的数十h中,0.1~0.2Hz频段的能量幅值出现明显的递增趋势,是非台风扰动引起的频率异常,与已有论文结论符合良好,证明Morlet小波变换是分析震前频率特征的有效方法。

This paper introduces the basic principles and characteristics of Morlet wavelet transform.As an example,we take the Wenchuan earthquake,using vertical continuous waveform seismometer data from May 1-12,2008.We then acquire the time-frequency spectrums by means of Morlet wavelet transform.According to the time-frequency spectrums,the energy amplitude of the 0.1~0.2 Hz band shows an obvious increasing trend several hours before the Wenchuan earthquake.This is a frequency anomaly caused by non-typhoon disturbances,which is well in line with existing conclusions.It is proven that Morlet wavelet transform is an effective method to analyze pre-earthquake frequency characteristics.