2012年4月11日苏门答腊M_S8.6地震前电离层TEC异常变化

Ionospheric TEC anomalies observed prior to the Sumatra M_s 8.6 earthquake on 11 April 2012

基于IGS提供的GPS TEC资料和中国地壳运动观测网络提供的GPS数据解算的单站VTEC数据,采用统计分析处理方法,对2012年4月11日苏门答腊北部M_S8.6地震震前电离层TEC资料进行处理分析,结果表明:在震前5—6天以及地震当天,震中上空附近出现显著的电离层TEC异常扰动,异常形态有正有负,表现为先异常减小后异常增大最后变小,异常增大主要发生在下午至黄昏时段,即12:00-16:00 LT,持续时间约4小时。排除太阳活动和地磁扰动的影响后,4月5日出现的电离层TEC异常增大及呈现出共轭结构以及地震当天出现的异常扰动,可能与此次地震有关。

A strong earthquake of magnitude 8.6 occurred near the west coast of Northern Sumatra, Indonesia, at 08：38： 36.5 UT on 11 April 2012 as a result of strike-slip faulting within the oceanic lithosphere of the Indo-Australia plate. Its epicenter was located at geographic lati- tude 02.31°N and longitude 93.06°E with depth of about 20.0 km. In this paper, on the basis of the Global Ionospheric Maps（GIMs） of Total Electron Content （TEC） provided by the International GNSS Service （IGS） network, we process and analyze the ionospheric TEC data prior to the Sumatra MsS. 6 earthquake by the method of the statical analysis, the results showed that ionospheric TEC anomalies include both anomalous increase and anoma- lous reduction a few days prior to the earthquake, the apparent anomalous increase of TEC occurred at 12：00-16：00 LT on April 5 which lasted for about four hours, due to the time was close to the moment when the earthquake occurred, it can be concluded the observed anomalous variations of the ionospheric TEC on April 5 is possibly related to the earthquake exclude the effect of solar activity and geomagnetic conditions.