基于地基GPS-TEC的中国区域地震电离层效应研究

Study on the Ionosphere Effect of Earthquakes in China Based on GPS-TEC

摘要:

基于中国陆态网络地基GPS-TEC观测，针对2008～2019年发生在中国区域的7个M_S≥6.0地震，采用滑动四分位距法分析了地震前后的电离层扰动时空分布特征。结果显示，5个地震的震前2～6天，GPS-TEC值出现负异常扰动，地震发生期间及震后电离层TEC出现正异常扰动，主要集中在震后2～7天；GPS观测站距离震中越近，垂直上空的TEC扰动越明显，扰动空间最大范围可达2000km。随着震级的增加，震前电离层TEC异常扰动的发生率有所增加，且异常覆盖的范围也有所扩大。因此，认为震前一周内的电离层TEC变化可能提供揭示电离层扰动与地震活动之间关系的线索。

Abstract:

By using data from CONOMOC ground-based GPS-TEC observations,we have applied the sliding interquartile range method to study the spatial-temporal distribution characteristics of ionospheric disturbances of seven M_S≥6.0 earthquakes occurred in continental China during 2008～2019. Our results show that the GPS-TEC values at observation stations show negative anomalies for five earthquake cases of seven events. TEC anomalies mainly appeared two to six days before the earthquakes. The ionospheric TEC positive abnormal disturbance during the earthquake,mainly concentrated two to seven days after the earthquake. The closer the station is to the epicenter,the larger the TEC anomalies becomes;during a few earthquakes TEC values increased significantly. Most of the earthquake cases show that and the closer the station is to the epicenter,the more obvious the TEC disturbance can be detected over the epicenter,with the maximum disturbance range of as much as 2000km away from the epicenter. With the increase of the magnitude of the earthquake,the occurrence rate of the ionospheric TEC anomaly before the earthquake is increased,and the coverage of the anomaly is also expanded. The results show that it is possible to identify ionospheric anomalies before earthquakes from continuous GPS observation data analysis. Therefore,we propose that monitoring ionospheric TEC changes within a week before the earthquake may be a clue to the relationship between ionospheric disturbances and seismic activities.