[S-SS16] 地殻変動

[SSS16-P23] Post-seismic deformation of 2016 Kumamoto Earthquake by continuous GNSS network (3)

*中尾 茂¹、松島 健²、田部井 隆雄³、大久保 慎人³、山品 匡史⁴、大倉 敬宏⁵、西村 卓也^7,6、澁谷 拓郎⁶、寺石 眞弘⁶、伊藤 武男⁷、鷺谷 威⁸、松廣 健二郎⁷、加藤 照之⁹、福田 淳一⁹、渡邉 篤志⁹、三浦 哲¹⁰、太田 雄策¹⁰、出町 知嗣¹⁰、高橋 浩晃¹¹、大園 真子¹¹、山口 照寛¹¹、岡田 和見¹¹ (1.鹿児島大学大学院理工学研究科地球環境科学専攻、2.九州大学大学院理学研究院地震火山観測研究センター、3.高知大学自然科学系理学部門、4.高知大学理学部附属高知地震観測所、5.京都大学大学院理学研究科火山研究センター、6.京都大学防災研究所、7.名古屋大学大学院環境学研究科地震火山研究センター、8.名古屋大学減災連携研究センター、9.東京大学地震研究所、10.東北大学大学院理学研究科地震・噴火予知研究観測センター、11.北海道大学大学院理学研究院地震火山研究観測センター)

キーワード：GNSS、余効変動

GNSS observation is ongoing in Kumamoto district to observe post-seismic deformation of 2016 Kumamoto Earthquake. We set up newly twenty continuous GNSS sites until April 30, 2016. Kyushu Univ., Kyoto Univ. and Kagoshima Univ. operate fifteen continuous GNSS sites before the earthquake. Daily coordinates of these sites are estimated by Bernese GNSS Software Ver. 5.2 with CODE precise orbit. ITRF2014 coordinate system is used. In our daily analysis, GEONET data by GSI and data at continuous GNSS sites in active volcanoes by JMA are also used. A dense continuous GNSS network is constructed.

To emphasize post-seismic deformation, trend at each site is removed. Trend is estimated by least squared method by using between 2004 to 2015. For GNSS sites occupied after the earthquake trend is interpolated by using trend at three neighbor sites.

Post-seismic deformation with large deformation is observed at sites which is located in the eastern side of Hinagu faults. Especially amount of deformation in NS component is large. Largest deformation is 13.5cm in the period from April, 2016 to December 2018 at MIFN. In EW component change in deformation occurred in January 2017. Velocity becomes smaller. In these sites post-seismic deformation is continuous at the moment.