摘要
以上海佘山实验地震台阵的测震记录为基础,研究了近震事件、远震事件及噪声不同的幅频特征.分析了影响台阵记录之间相关性质的一些主要因素:当子台间距增大时,记录之间相关性降低;当间距固定时,所记录事件的相关性质受信号的频率、震中距(波阵面的入射角)及噪声振动背景的影响.提出了一维时间序列滤波函数的优化结果并不是二维台阵的最佳频率窗.欲取得较好的聚束信噪比,滤波函数不仅考虑压制噪音振动,还要考虑压制信号的非相关频段.
On the base of the data of Sheshan seismic testing array in Shanghai,the features of frequency and amplitude of noise,near event and far event are studied.Some factors affecting correlation among the records of substations in the array are discussed.With the distance between substations getting longer,the correlation tend to be smaller;with the distance fixed,the correlation depends on single frequency,epicentral distance (angle of incidence),and the noise vibration.Wiener singlechannel frequency filters are not best to use in filtering original data for beamform.The filters would be designed not only to depress noise but also to keep the well correlated signals in order to beamform better.
引文
[1] 国家地震局科技监测司.地震观测技术[M].北京:地震出版社,1995.
[2] JohnPB.Theree dimensionalfilteringwithanarrayofseismimeters[J].Geophysics,1964,29(5):693—713.