| Seismic wave recognition is an important basis for seismic data processing.Its recognition speed,accuracy and reliability directly affect the efficiency of research work such as earthquake early warning and focal mechanism analysis.However,with the development of social economy and the acceleration of industrialization,the background noise of seismic observation environment is becoming more and more complex.For example,vehicle driving,construction and other activities bring some challenges to seismic wave identification.How to effectively use limited stations or mobile stations to identify seismic waves in real time,accurately and reliably is of great significance for earthquake monitoring,earthquake trend judgment and emergency decision-making.Therefore,this thesis focuses on the study of seismic wave identification in complex noise environment.Based on the research of seismic wave identification technology at home and abroad,a comprehensive seismic wave identification method based on seismic wave identification at a few stations is proposed.The main research work includes:(1)The Short Term Average/Long Term Average(STA/LTA)method is subject to short-term strong noise interference and high false recognition rate.Based on the signal-to-noise ratio(SNR)characteristic function,this thesis proposes a STA/LTA method combining delay long window and cancellation time window,which enhances the anti-interference ability of the algorithm.(2)The application effects of STA/LTA method and polarization analysis method in actual seismic data processing are compared and analyzed.The analysis results show that the STA/LTA method has weak anti-noise interference ability and the polarization analysis method has high leakage recognition rate.In order to solve this problem,this thesis proposes a comprehensive seismic wave recognition method based on single station combined with STA/LTA,polarization analysis and AIC.The experimental results of 140 different types of seismic records show that the comprehensive seismic wave recognition method based on single station is more accurate than the traditional seismic wave recognition method based on single feature of seismic signal.(3)Aiming at the problem of low reliability of seismic wave identification results based on a single station,this thesis proposes a seismic wave identification method based on Delaunay(referred to as D)triangulation according to the characteristics of’homology’of seismic waves detected by multiple stations.On this basis,the compatibility between the peak displacement P_d of seismic ground motion and the characteristic periodτ_c is used as the basis for judging whether the trigger information is a real seismic wave,and a double parameter test method of seismic wave based on D triangulation is proposed.The experimental results of 96 natural seismic events show that the compatibility between the P_d andτ_c parameters of seismic waves calculated based on D triangulation is higher,and the proportion of seismic waves in the absolute compatibility and partial compatibility regions is increased from 90.7%of the traditional method to 96.88%.The seismic wave double parameter test method based on D triangulation can well eliminate noise interference and accurately identify seismic waves. |
