摘要
精密主动地震监测为我们主动探测地下介质结构,并监视其动态变化提供了一条可能的技术途径。由于精密控制震源释放的能量强度小,随着传播距离的增加,信号的快速衰减,在离震源较远处有用的震源信号被掩盖在很强的噪声中,这对于震相的识别与走时的拾取精度有着很大的影响。本文设计了一种时变窄带滤波器进行更为精细的滤波,期望进一步提高观测数据信噪比,再结合匹配滤波方法实现主动震源信号的检测与波形变换。另外,由于不同震相有一定的到时差,使用时变窄带滤波器提取一个震相波形信息时,将压制其他震相的波形信号,从而实现了震相分离的技术。仿真计算与实际资料处理显示了该方法在提高观测资料质量、震相识别分辨率及震相分离方面具有一定的有效性与优越性。通过对广东省新丰江库区精密可控震源试验数据进行时变窄带滤波方法的处理,在震中距为200km左右处的台站记录中检测到主动源信号,体现了对远台弱信号的提取能力。
Precise and Active Seismic Monitoring （PASM） system introduced in this paper may provide an approach to explore crustal structures and monitor its temporal variation. With the increase of propagation distance, useful signal is masked in strong noise as the energy intensity radiated by it is quite small. Strong noise has a great impact on identifying phases and picking accuracy of travel time. In this study, we propse a new method for time-varying narrow band-pass filter design to achieve precise filtering effect, and retrieve CASS chrip signal by cross-correlation to identify the major seismic phases traveling through the crust. Besides, because of different travel time between different seismic pha- ses, we retrieve certain impulsive seismic waveforms by using time-varying narrow bandpass filter, which suppresses the other seismic phases. Finally, The effectiveness and prac- ticability of the new optimized algorithm in extracting chrip signal, raising the resolution phase and seismic phases separation is proved by applying it to model and actual seismic data. The retrieved impulsive seismic waveforms at station 200 km away reflectes the capacity of weaker signal detection.
出处
《地震》
CSCD
北大核心
2015年第3期44-56,共13页
Earthquake
基金
中国地震局地震预测研究所基本科研业务费专项(2014IES0202)资助
