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基于前人整理的“前驱波”特征和小波变换理论,应用小波方法分析了2001年11月14日昆仑山口西MS8.1和2004年12月26日苏门答腊MS8.7地震前30天山东泰安台体应变观测分钟值的高通滤波数据。研究表明,在昆仑山口西MS8.1地震前,高通滤波数据和小波分析结果比较正常。苏门答腊MS8.7地震前,高通滤波数据呈与气压相关变化,无明显异常,但小波分析结果细节部分第1、2层在12月5日左右有类似“前驱波”信号出现,波幅变化在±0.5×10-9之间,主要周期成分在2～4分钟之间,持续时间1天左右,与同时段气压变化形态不一致,对这种异常现象需要做进一步的分析。小波变换能够提取出体应变资料中的微弱变化信号,是检验强震“前驱波”的一种有效方法。
Based on the predecessor ’s “precursor wave ” characteristics and wavelet transform theory, wavelet analysis was used to analyze the Kunlun Mountain west MS8.1 on November 14, 2001 and the 30 days before Sumatra MS8.7 earthquake on December 26, 2004 Taian Taiwan body strain observation minute value of the high-pass filter data. Research shows that before the Kunlun Mountain Pass MS8.1 earthquake, the results of high-pass filtering and wavelet analysis are normal. Prior to the Sumatra MS8.7 earthquake, the HPT data showed a change related to barometric pressure with no significant anomalies. However, the first and second tiers of the wavelet analysis detail appeared similar to the “precursor wave” signal on Dec. 5, with fluctuations in amplitude Within ± 0.5 × 10-9, the main periodic components are between 2 and 4 minutes and the duration is about 1 day, which is different from the change of atmospheric pressure at the same time. This anomaly needs to be further analyzed. Wavelet transform can extract the weak change signal in the body strain data, which is an effective method to test strong earthquake “precursor wave ”.