【摘要】 利用汶川8.0级大地震震中周围16个台站的四分量钻孔应变观测资料,对地震前驱波进行检验。用高通滤波消除周期>128分钟的固体潮汐影响,用回归分析方法消除气压干扰,用小波变换方法将2~128分钟的信号分解到6个不同频段进行分析,结果显示小波变换方法能提取出信号中的微弱变化信息。根据小波变换提取的类似前驱波基本特征,利用"超限率"分析方法检验小波分解的细节部分,并对所有细节部分的超限率时间序列的拟合直线斜率进行统计,得出平均值和标准差。两项统计数据显示,震前15天之内不能普遍检测到地震前驱波。更多还原

【Abstract】 The precursory waves before Wenchuan 8.0 earthquake are statistically tested by use of the observed strain data with the 4-component borehole strainmeters at 16 stations around the epicenter.In which,first of all,the influence of solid tide whose period is longer than 128 minutes is removed with high-pass filter,and the secondly,air-pressure influence is removed with linear regression method,and then the signals for 2～128 minutes are decomposed into 6 different kinds of frequency bands with wavelet transform method. The results indicat that wavelet transform can be used to identify small change existed in deformation signal.On the basis of the characteristics of precursory wave indentified by wavelet transform,and the overrun rate method will be used to test the details of wavelet decomposing,and then the regression line slope of the overrun rate time sequence of entire details will be statisticed,thus the average and standard deviation can be obtained.These data show that precursory waves can not be generally detected during 15 day before earthquake.更多还原