2014年鲁甸6.5级地震震前TEC异常分析

Analysis of TEC anomalies before the 2014 MW 6.5 Ludian earthquake

2014年8月3日云南省鲁甸发生了6.5级地震。针对震前电离层异常问题,利用IGS提供的全球电离层数据,采用滑动四分位法对鲁甸地震震中及其周围格网点的TEC进行异常探测,发现震前3d、6d和13d电离层有明显的异常,其中震前3d、6d的异常最为显著。在进一步分析了太阳地磁活动及这几天的全球TEC异常分布后,认为这3d的电离层异常可能与震前的孕育地震有关。另外,这3d的TEC异常分布区域都满足在经度方向跨度和纬度方向跨度长度比约为3∶1,且异常的峰值点并不位于震中的正上方,而是位于震中偏向赤道方向,同时赤道共轭区域也存在异常,但范围和幅度都较小。

On August 3,2014,an earthquake of Mw 6.5occurred at Ludian of Yunnan Province,China.The ionospheric anomalies before the earthquake are studied using global ionospheric data from IGS.TEC time series over the epicenter and its surrounding areas are detected with the sliding inter quartile range method with the sliding window of 15 days.It can be found that there were obvious ionospheric anomalies in the 3th,6thand 13 th days before the earthquake,especially in the 3th,6th days before the earthquake.After the further analysis of the solar geomagnetic activities and the global TEC anomaly maps,it can be considered that the pre-earthquake anomalies in these days may have a large correlation with the earthquake preparation.In addition,the affected ionospheric area on these days before the earthquake extended to longitude and latitude with the length ratio of 3∶1roughly,and the location of anomaly peak didn′t coincide with the vertical projection of the epicenter,but was closer to the equator.Corresponding ionospheric anomalies are also observed in the magnetically conjugated region,but the scopes and amplitudes were smaller.