论文部分内容阅读
采用山东省泰安台观测精度达10-9量级的钻孔体应变仪观测资料,深入分析了2001—2005年MS≥7.5强远震前应变变化,对“前驱波”进行了客观、系统的检验.用高通滤波消除了周期大于128min的固体潮汐影响,然后用回归分析方法消除了气压的干扰.用小波变换方法将2—128min信号分解到6个不同频段进行分析.小波分析结果表明,该方法能提取出信号中微弱变化信息.根据小波变换提取的类似“前驱波”基本特征,提出了“超限率”方法,并对这种波形是否普遍存在进行了检验.该方法将单位时间内超过标准差的数据个数定义为单个超限率,类似“前驱波”波形存在时段内的超限率将高于正常时段.据此得出震前30天的超限率时间序列.用直线拟合该序列,最后对直线斜率进行统计分析.用超限率方法分析了所有小波分解的细节部分,得出了超限率时间序列的回归直线斜率的平均值和标准差,并分析其正负比.这3项统计数据显示,强远震前15天之内不能普遍检测到“前驱波”.
Based on the observation data of borehole strain gauges with the observation accuracy of 10-9 in Tai’ai station of Shandong province, the change of strain before MS≥7.5 strong earthquakes in 2001-2005 was analyzed in depth and the objective, System.The high-pass filter was used to eliminate the influence of solid tides with period of more than 128min and then the atmospheric pressure was eliminated by regression analysis.The signal of 2-128min was decomposed into six different frequency bands by wavelet transform.The wavelet analysis showed , This method can extract the weak information of the signal.According to the similar “precursor wave ” basic features extracted by the wavelet transform, the “overrun rate ” method is proposed and the existence of this waveform is tested. In this method, the number of data exceeding the standard deviation per unit time is defined as a single overrun rate, and the overrun rate in the period similar to the “precursor wave” waveform will be higher than the normal period. The rate of overrun time series.Finally, the sequence was fitted by straight line, and finally the slope of the line was statistically analyzed.The details of all the wavelet decompositions were analyzed by the overrun rate method, and the average of the regression line slope of the overrun rate time series was obtained with Level differences, and to analyze the positive and negative ratio. This 3 Statistics show that generally can not be detected before strong “precursor wave ” within 15 days of distant earthquakes.