[M-IS10] Interdisciplinary studies on pre-earthquake processes

[MIS10-10] Behavior of Ionosphere before 2011 Tohoku-Oki Earthquake

*Koichiro Oyama¹, Jia-Hong Chen² (1.International Center for Space Weather Study and Education, Kyushu University, 2.Departments of Earth Sciences, National Cheng Kung University, Tainan, Taiwan)

Keywords:Earthquake, Ionosphere, Ground motion

NmF2 before large earthquakes has been studied by many scientists by picking up the deviation of NmF2 from the normal behavior. However, this is not enough to study the precursor anomaly. We need to study the daily behavior of the NmF2 as well as h’F at several stations which are located at different longitudes and geomagnetic latitudes. To add space weather parameter, such as Kp index, Dst, and F10.7 might be essential. Depending on the geomagnetic latitude especially, the NmF2 shows different behavior; at one location daytime NmF2 shows the peak, while at other location, it shows the minimum. The night time NmF2 at high latitude exceeds almost two times from the normal daily values. These behaviors is explained by the intensity of the electric field which we is considered to be the driver modifying the ionosphere. In addition to the parameters including both ionosphere the space weather, the vertical ground motion which are measured with the slant gages distributed inside Japan needs to be carefully studied. We stress here that to study both the spontaneous variation of frequency spectrum and power spectrum density (PSD) might provide the possibility to identify the location of the epicenter and the day of the earthquake