[S-SS09] Crustal Deformation

[SSS09-P04] Post-seismic deformation of 2016 Kumamoto Earthquake by continuous GNSS network (2)

*Shigeru Nakao¹, Takeshi Matsushima², Takao Tabei³, Makoto OKUBO⁴, Tadashi Yamashina⁴, Takahiro Ohkura⁵, Takuya NISHIMURA⁶, Takuo Shibutani⁶, Masahiro Teraishi⁶, Takeo Ito⁷, Takeshi Sagiya⁸, Kenjiro Matsuhiro⁷, Teruyuki Kato⁹, Jun'ichi Fukuda⁹, Atsushi Watanabe⁹, Satoshi Miura¹⁰, Yusaku Ohta¹⁰, Tomotsugu Demachi¹⁰, Hiroaki Takahashi¹¹, Mako Ohzono¹¹, Teruhiro Yamaguchi¹¹, Kazumi Okada¹¹ (1.Department of Earth and Environmental Sciences, Graduate School of Science and Engineering, Kagoshima University, 2.Institute of Seismology and Volcanology, Faculty of Sciences, Kyushu University, 3.Department of Global Environment and Disaster Prevenction, Faculty of Science and Technology, Kochi University, 4.Kochi Earthquake Observatory, Faculty of Science and Technology ,Kochi University, 5.Aso Volcanological Laboratory, Institute for Geothermal Sciences, Graduate School of Science, Kyoto University, 6.Disaster Prevention Research Institute, Kyoto University, 7.Earthquake and Volcano Research Center, Graduate School of Environmental Studies, Nagoya University, 8.Disaster Mitigation Research Center, Nagoya University, 9.Earthquake Research Institute, University of Tokyo, 10.Research Center for Prediction of Earthquakes and Volcanic Eruptions, Graduate School of Science, Tohoku University, 11.Institute of Seismology and Valcanology, Graduate School of Science, Hokkaido University)

Keywords:Continuous GNSS observation, post-seismic deformation, 2016 Kumamoto Earthquake

Post-seismic deformation has been observed since April 15, 2016 by extraordinary GNSS observations of 20 sites and cooperative GNSS observations of 15 sites by Kyushu University, Kyoto University and Kagoshima University. Extraordinary GNSS sites started observation in April, 2016 after occurrence of 2016 Kumamoto Earthquake. Cooperative GNSS observations have observed continuously before the earthquake. Bernese GNSS Software V. 5.2 are used for GNSS data analysis with GEONET data, which is operated by GSI and JMA GNSS continuous data in Kyushu. CODE precise ephemerides and Earth rotation pole data are used.
Plate motion in each site should be removed from post-seismic deformation data. Displacement velocities of GNSS sites are estimated by Least Squares method in the period from 2004 to 2013. Displacement velocities of extraordinary GNSS sites are interpolated by velocities around the sites. Post-seismic deformation is derived by extracting the displacement velocity of plate motion.
Post-seismic deformation is observed at sites which are located on the south-east side of Hinagu fault, especially on NS component until December 2017. It seems that clear post-seismic deformation continues until early part of June, 2016 at sites which are located on the north-west side of Hinagu faults. Change in NS component around May, 2017 and in EW component around August, 2017 occurred at sites which are located on both sides of Hinagu fault.