Earthquake Electromagnetic Signal Analysis And Research

The process of gestation and occurrence of an earthquake is extremely complicated.A large number of studies have shown that a seismic event is usually accompanied by an abnormal change in a number of physical quantities.Among these physical quantities,changes in the magnetotelluric field are more sensitive to the reflection of seismic events.This paper mainly focuses on how to extract and identify anomalous signals associated with seismic events from magnetotelluric observations.This will effectively deepen the understanding of the magnetotelluric effect as well as increase the role of seismic observation data in earthquake prevention and mitigation.This paper briefly describes the research background and significance of magnetotelluric signal analysis,and summarizes the research status at home and abroad.On this basis,the wavelet transform method,the fractal analysis method and the LoCo method were respectively used to extract the abnormal signals of geomagnetic signals in magnetotelluric signals from the following three angles,signal decomposition,signal geometry and nonlinear signal similarity.And also,the theoretical basis of the three algorithms has been introduced respectively,which has been applied to the anomaly extraction of actual seismic cases.First,the geomagnetic observation data of the MS 6.6 Minxian-Zhangxian earthquake which was in Gansu Province has been processed using wavelet transform algorithm and fractal analysis algorithm.Initially,fractal analysis has been used to analyze the original observation signal.It has been found that there were only 3 stations with abnormal signals in 15 stations.Therefore,the original observation signal has been subjected to multiresolution decomposition by wavelet transform.After statistical analysis,it has been found that 6 stations exhibited abnormal signals similar to the above three stations.All abnormalities have good synchronicity and obvious numerical abnormalities,which may be affected by the same source.Subsequently,this method has been applied to the effective signal value of the Baoying-Gaoyou earthquake case,which also achieved good results.Then,the LoCo algorithm has been used to process the geomagnetic observation data of the MS 6.6 Minxian-Zhangxian earthquake in Gansu Province..Because of the regional nature of the electromagnetic field,the LoCo score between the observations of electromagnetic stations in a certain area should be close to 1.According to this characteristic,this chapter divides 13 stations into 4 groups according to the distance between the stations and LoCo calculations are performed for each station in pairs.According to the statistical analysis results,this chapter mainly extracted two anomalies,which may be affected by the same source and have a certain correlation with the earthquake event.Finally,this paper develops a magnetotelluric signal analysis software based on Matlab GUI and integrates the three methods studied in the paper.The software supports the observation data collected by the FHD-2 instrument and the GM-4 instrument in the seismic system,providing the research of the analog signal and the measured signal.Besides,this software can be used to perform quick and convenient analysis of the magnetotelluric signal,which will have a better application value.