Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake
Ionospheric disturbances detected by GPS total electron content observation after the 2011 off the Pacific coast of Tohoku Earthquake
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DOI：
10.5047/eps.2011.06.035
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发表时间：
2011-01-01
影响因子：
3
通讯作者：
Murata, K. T.
中科院分区：
文献类型：
--
作者：
Tsugawa, T.;Saito, A.;Murata, K. T.
2011年东北大地震后电离层扰动的所有细节都是由日本的高分辨率GPS总电子含量观测首次揭示的。最初的电离层扰动出现突然耗尽后，小脉冲TEC增强类似于7分钟后，地震发生，震中附近。然后，同心波似乎以138- 3，457 m/s的速度在径向方向上传播。日本西部也出现了TEC的纬向扩展增强。在震中附近，观测到了周期约为4分钟的短周期振荡。本文主要研究同心波。同心圆图案表明他们有一个点源。这些结构的中心，被称为“电离层震中”，位于东南方向距离震中约170公里。根据传播特性，这些同心波可能是由大气波引起的，分为三类：由传播的瑞利波产生的声波，来自电离层震中的声波和来自电离层震中的大气重力波。同心波的振幅是不均匀的，并依赖于其传播方向的方位角，这不能用先前提出的理论来解释。
All the details of ionospheric disturbances following the 2011 Tohoku Earthquake were first revealed by the high-resolution GPS total electron content observation in Japan. The initial ionospheric disturbance appeared as sudden depletions following small impulsive TEC enhancements similar to 7 minutes after the earthquake onset, near the epicenter. Then, concentric waves appeared to propagate in the radial direction with a velocity of 138-3,457 m/s. Zonally-extended enhancements of the TEC also appeared in the west of Japan. In the vicinity of the epicenter, short-period oscillations with a period of similar to 4 minutes were observed. This paper focuses on the concentric waves. The concentric pattern indicates that they had a point source. The center of these structures, termed the "ionospheric epicenter", was located about 170 km from the epicenter in the southeast direction. According to the propagation characteristics, these concentric waves could be caused by atmospheric waves classified into three types: acoustic waves generated from a propagating Rayleigh wave, acoustic waves from the ionospheric epicenter, and atmospheric gravity waves from the ionospheric epicenter. The amplitude of the concentric waves was not uniform and was dependent on the azimuth of their propagation direction, which could not be explained by previously-proposed theory.