基于小波变换方法的包头台形变分析

Deformation Analysis of Baotou Seismic Station Based on Wavelet Transform Method

采用小波变换方法相继对包头台洞体应变和水管倾斜进行处理,研究形变数据固体潮、同震响应和周期性特征等。采用db4作为母小波对包头台形变进行5阶小波分解,分解后的细节部分能清晰地显示出包括1/3日波、半日波、日波和半月波等在内的固体潮汐波。对于2008年以来全球发生的M≥8.0级地震,包头台水管倾斜NS分量均有显著的同震响应现象发生,且在小波分解后的不同阶曲线中同震响应后续波形表现各异,另外在部分地震之前能观测到异常变化。采用Morlet小波作为母小波对包头台水管倾斜NS分量进行小波变换分析,获得的小波变换系数分布图能清晰地显示出倾斜数据中存在的包括半日潮和日潮在内的周期特征及其随时间变化情况。

By using wavelet transform method to process the cave strain and water tube tilimeter at Baotou station, the paper studied the earth tide, co-seismic response and periodic characteristics of the deformation. The paper analyzed the 5-level wavelet decomposition for deformation at Baotou seismic station with mother wavelet db4 and got the result that 1/3 daily wave, semi diurnal tide wave, daily wave and half lunar wave existed in the detail decomposing signal of wavelet. The co-seismic responses of NS component tilt data at Baotou seismic station occurred during all earthquakes with M ≥8.0 in the world since 2008, which has different characteristics in various levels wavelet decomposition, and abnormal changes exist before some earthquakes. The paper did the wavelet transform analysis on NS component tilt data at Baotou seismic station by using the mother wavelet Morlet, and obtained the distribution map of wavelet transform coefficient, which shows the time evolution characteristics of periodic obviously.