ICA-based Cross-correlation Spectrum Analysis Of Gravity Tide Signals And Anomaly Information Extraction

China is a country with frequent earthquakes,and because of the certain triggering relationship between solid tides and earthquakes,the study of solid tides is of great significance to earthquakes in China.However,the gravity tide signal contains a very rich tidal harmonic component.How to extract the earthquake precursor information that is physically related to the earthquake from the observation data has always been the subject of scholars' research.It is known from the mechanism of the generation of the gravity tide signal that it is composed of a relatively strong energy daily wave,a half-day wave component,and a long-period wave component such as an annual wave and a moon wave with relatively weak energy.Therefore,Among the harmonic components of larger energy differences,it is difficult to highlight the abnormal information with weaker energy.Therefore,in order to carry out effective analysis,it is necessary to first separate the strong and weak tidal harmonic components of the gravity solid tide signal.The research work of this paper is as follows:This paper is based on a gravity solid tide decomposition model.According to this model,this paper uses the independent component analysis to decompose the signal,successfully decomposes the signal into three paths,and the three independent components and the three-dimensional orthogonal decomposition model correspond one-to-one,which proves that the components are mutually orthogonally formed by gravity.Solid tide signal.In the spectral correlation analysis of the components of independent components,the autocorrelation operation will make the strong component stronger and the weaker component weaker.For this problem,this paper uses the cross-correlation spectrum between independent components to highlight the weak tidal harmonics.The component,which achieves higher-resolution spectral correlation analysis,reveals the modulation relationship between gravity solid tide and harmonic components,so that more abundant harmonic modulation information between harmonic components can be obtained,and weak earthquake precursor information is highlighted.By comparing with the calculated values of tidal harmonic frequency theory,it is found that there is a general relationship between direct or indirect multiplicative modulation between tidal harmonic components,which proves that the algorithm of this paper not only effectively separates gravity from the perspective of additive decomposition.The independent component with large difference in intensity among the solid tide signals,and based on the cross-correlation spectrum between the independent components,reveals the relationship of multiplicative modulation prevalent between tidal harmonics,thus successfully revealing the gravity tide signal.Superposition and modulation between various tidal harmonic components.On this basis,the actual earthquake cases in three time periods in Yunnan are selected for analysis,and compared with the calculated values of tidal harmonic theory,it is found that the long-period harmonic components are more compared with the daily and half-day waves,and the theoretical calculations exist.The obvious and common error indicates that the long-period harmonic component can more clearly reflect the earthquake precursor information existing in the gravity solid tide signal in the seismic scene compared with the daily wave and the half-day wave.