地震工程学报2016，Vol.38Issue(1)：136-143,149,9.DOI:10.3969/j.issn.1000-0844.2016.01.0136
台站地震资料的时频域自适应极化分析和滤波
Adaptive Polarization Analysis and Filtering of Station Seismic Data in Time-Frequency Domain
摘要
Abstract
Polarization filtering methods based on a covariance matrix play an important role in the processing of multicomponent seismograms due to their explicit physical meaning,ease of imple-mentation,and high efficiency.Conventional polarization filtering methods that are realized in a time domain have major limitations in resolving seismic signals in which waveforms or frequencies overlap.Time-frequency analysis methods are especially suitable for resolving separate seismic signals that overlap in time but have different spectra for instantaneous signal analysis.These methods can describe frequency components of a signal that change over time.Owing to the advantages of the time-frequency analysis method,it can be used in polarization analysis.This study presents a polarization filtering method based on the generalized S-transform to suppress surface waves in a time-frequency domain.On one hand,we remold the window function of the S-transform and improve the frequency resolution of seismic signals by increasing regulatory factors to create a nonlinear change in the window function with the signal frequency.On the other,we structure the cross-energy matrix in the time-frequency domain using the generalized S-trans-form,compute instantaneous polarization attributes by eigenanalysis,and design a filtering algo-rithm in the time-frequency domain to achieve polarization filtering of multicomponent seismic signals.The specialties of this method are that the length of the time window of the covariance matrix is determined by the instantaneous frequency of the multicomponent seismic data and it can adapt to the dominant period of the desired signal.Moreover,it calculates polarization param-eters at each time-frequency point and no longer needs to perform interpolation.It is particularly accurate in processing signals with overlapping waveforms or frequencies in the time or frequency domain.The results of processing data from models and real three-component seismograms show that this method has very high clarity,high resolution,and practicability in the data analysis and processing of seismograms.This representation enables the detection of dispersion in polarization attributes,which can be further exploited to infer some physical characteristics of the medium under investigation.Moreover,this representation offers the ability to distinguish between attrib-utes that belong to different coherent events that may overlap in time but with different frequency contents separated by time-dependent frequency cutoffs.Identifying and separating different wave types are made possible by designing filters that operate in the time-frequency domain.Attributes such as azimuth,dip,and signed ellipticity can also be used to improve the filtering algorithms.关键词
极化滤波/时频分析/广义S变换/自适应协方差矩阵/多分量地震Key words
polarization filtering/time-frequency analysis/generalized S-transform/adaptive covariance matrix/multi-component seismogram分类
天文与地球科学引用本文复制引用
马见青,李庆春,王卫东,王美丁,李春兰..台站地震资料的时频域自适应极化分析和滤波[J].地震工程学报,2016,38(1):136-143,149,9.基金项目
国家自然科学基金项目(41374145) （41374145）
高等学校博士点基金项目(20120205130002) （20120205130002）
中央高校基金项目(310826161008) （310826161008）
