Analysis of ionospheric anomalies before the 2011 M_w 9.0 Japan earthquake  

作　　者：YAO YiBin CHEN Peng WU Han ZHANG Shun PENG WenFei 

机构地区：[1]School of Geodesy and Geomatics,Wuhan University,Wuhan 430079,China

出　　处：《Chinese Science Bulletin》2012年第5期500-510,共11页

基　　金：the Key Laboratory of Geospace Environment and Geodesy (Wuhan University), Ministry of Education;supported by the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (40721001);the Surveying and Mapping Foundation Research Fund Program, State Bureau of Surveying and Mapping (10-02-13)

摘　　要：On March 11, 2011, a large earthquake of Mw=9.0 occurred near the east coast of Honshu, Japan. This paper investigates preearthquake ionospheric anomalies during the earthquake period, using data from global navigation satellite systems and ionosonde stations near the epicenter. A clear anomaly that occurred on March 8 lasted 6 hours. Eliminating ionospheric anomalies that may have been caused by solar activities and magnetic storms, we believe that a positive anomaly on March 8 was very possibly an ionospheric precursor. The affected ionospheric area on March 8, which is evident on a vertical total electron content distribution map, extended to 50° in longitude and 20° in latitude, with length ratio approximately 3:1. The anomaly peak arose from 15:00-19:00 LT, and its location did not coincide with the vertical projection of the epicenter, but was instead to its south. Corresponding ionospheric anomalies are also observed in the magnetically conjugated region. There were no obvious ionospheric anomalies in other parts of the world. To analyze changes in the ionospheric anomaly, computerized ionospheric tomography technology was used to invert the spatial and temporal distribution of electron density in the ionosphere. The ionospheric anomaly on March 8, 2011 is suggested to be an ionospheric precursor of the March 11 earthquake in Japan.On March 11,2011, a large earthquake of Mw=9.0 occurred near the east coast of Honshu, Japan. This paper investigates pre- earthquake ionospheric anomalies during the earthquake period, using data from global navigation satellite systems and ionosonde stations near the epicenter. A clear anomaly that occurred on March 8 lasted 6 hours. Eliminating ionospheric anomalies that may have been caused by solar activities and magnetic storms, we believe that a positive anomaly on March 8 was very possibly an ionospheric precursor. The affected ionospheric area on March 8, which is evident on a vertical total electron content distribution map, extended to 50° in longitude and 20° in latitude, with length ratio approximately 3： 1. The anomaly peak arose from 15：00- 19：00 LT, and its location did not coincide with the vertical projection of the epicenter, but was instead to its south. Correspond- ing ionospheric anomalies are also observed in the magnetically conjugated region. There were no obvious ionospheric anomalies in other parts of the world. To analyze changes in the ionospheric anomaly, computerized ionospheric tomography technology was used to invert the spatial and temporal distribution of electron density in the ionosphere. The ionospheric anomaly on March 8, 2011 is suggested to be an ionospheric precursor of the March 11 earthquake in Japan.

关 键 词：电离层异常 地震前 日本 全球导航卫星系统 垂直投影 总电子含量 太阳活动 电子密度 

分 类 号：P352.5[天文地球—空间物理学] P315.7[天文地球—地球物理学]