[P-EM12] 大気圏ー電離圏結合

[PEM12-30] Enhanced Electric Field Before Large Earthquakes

*小山 孝一郎^1,2,3、柿並 義宏⁴、陳 佳宏⁵、魚住 禎司² (1.台湾国立成功プラズマ宇宙科学研究所 　、2.九州大学国際宇宙天気研究・教育センタ、3.アジア宇宙環境研究機構（株）、4.北海道情報大学、5.台湾国立成功大学地球科学科)

キーワード：電離圏、地震、電場、波動

Electric field seems to be a main driver which disturbs ionosphere prior to large earthquake. The problem is where and how the electric field is generated. We have proposed that electric field is originally dynamo field which appears ionosphere E and F region. It enhances around the epicenter region. That is, during daytime the eastward electric field is enhanced, while during nigh time, westward electric field is enhanced. This idea explains all ionosphere anomalies which we have found from the past studies (Oyama et al., 2008; Oyama et al., 2011 ;Oyama et al., 2019). Next question is the mechanism of enhanced dynamo E field. Most probably, Pedersen conductivity of E/F region reduced. The electric potential which exists between dawn and dusk is divided by the conductivity of the earthquake-disturbed region, resulting in the stronger E field in the disturbed region. Further question is the mechanism of reduced conductivity. The conductivity is reduced by irregularity of neutral particle density and by increase of neutral density. These two are generated by the breaking of gravity and/or acoustic waves.