Analysis Of Ionospheric And Temperature Anomalies Before Strong Earthquakes

Earthquake early warning has always been a difficult problem in seismology.In recent years,many studies have shown that there will be abnormal phenomena before earthquakes,such as ionospheric anomalies and temperature anomalies.These abnormal phenomena are caused by the accumulation and release of energy before earthquakes.With the development of GNSS technology and remote sensing technology,there are more and more researches on seismic-ionospheric anomalies using GNSS technology and seismic-temperature anomalies using remote sensing technology.It is found that the ionospheric anomaly will appear near the epicenter about one week before the earthquake,and a large area of warming anomaly will appear over the seismogenic area several days or even months before the earthquake,and the abnormal changes have a good coupling with the crustal structure.In the study of pre-earthquake anomalies,the two kinds of anomalies are basically separated,and the combination of the two is rarely studied.Based on this,this paper,on the basis of previous studies,uses VTEC inversion of GNSS technology and existing anomaly detection technology to study ionospheric anomalies before earthquakes,uses temperature data and anomaly processing methods to detect temperature anomalies before earthquakes,and makes preliminary analysis and discussion of the two.Specific research results are as follows:1.The comparison of earthquake cases in New Zealand in 2016 shows that both of the two pre-earthquake ionospheric anomaly extraction methods can extract earthquake ionospheric anomaly information in the same earthquake case,but the sliding quartile distance method can extract more effective earthquake anomaly information.2.The high-precision VTEC calculated by GNSS data and the sliding quad distance method were used to detect the ionospheric anomalies before six strong earthquakes in New Zealand,Nepal,Chile and Japan,respectively,to exclude the influence of the solar space environment and screen out the anomaly information related to earthquakes.The results show that :(1)most ionospheric anomalies occur within one week before the earthquake,and most of them are positive anomalies.(2)The larger the magnitude is,the larger the magnitude of anomalies will be;(3)The magnitude of anomalies detected in the same direction over the seismogenic area decreases with the increase of epicentral distance.3.Combined with the temperature anomaly information of six strong earthquakes extracted from celestial tide-generating force,the following results are obtained :(1)earthquakes mostly occur at the peak or trough of celestial tide-generating force;(2)6earthquake short-term and impending temperature before the earthquake are the initial warming-strengthening of warming-the attenuation of warming-again-restore calm abnormal changes of warming,and the ionosphere anomaly occurred after the initial warming,two kinds of anomaly area has a high degree of overlap,so that the two are not exist in isolation,but has a certain time and space relevance.