基于Daubechies小波分析的南京数字化钻孔形变震前变化特征研究

应用小波分析理论及其时频分析方法,阐述了高低频信息的识别和小波基的选取,并对南京地区2006—2012年数字化应变观测整点值资料进行了小波多分辨率分析。结果表明,六合台体应变小波分解7—9阶是频率最低的部分,异常信号的周期在24—30天左右,持续时间在1—2个月之间,具有明显的短期、临震异常特征;江宁台四分量应变的整点观测值的第9阶小波分解表明,在发生2次地震前,四分量中至少有3个方向的分量出现了明显的异常情况,这种异常周期通常在20—30天左右,其与高淳台的异常周期时间相当,它可能是地震的前兆信号。

Anomalies Characteristics of Digital Data of Borehole Deformation before the Earthquakes at the Nanjing Region Based on Daubechies Wavelet Analysis

The theory of wavelet analysis and the time-frequency analysis method are applied. The authors expound a method for extracting high or low-frequency information from original recording signals and selection of wavelet. And the authors applied the method to extract anomalies of the hourly digital data of deformation before earthquakes in the Nanjing region from 2006 to 2012. The study shows that digital signals of deformation anomalies appear for a period of 24-30 days before earthquakes at the Liuhe seismostations, with the duration for about 1 to 2 months. The 9th level wavelet decomposition of Jiangning seismostation shows that the multi-component borehole strainmenter appear anomalies in at least three-component and the cycle is usually 20 to 30 days. These signals may be earthquake precursors.