*Yuji Abe¹, Mamoru Nakamura² (1.Graduate School of Engineering and Science , University of the Ryukyus, 2.Faculty of Science, University of the Ryukyus)

*Mamoru Nakamura¹ (1.Faculty of Science, University of the Ryukyus)

*Mamoru Nakamura¹, Yuji Abe¹ (1.Faculty of Science, University of the Ryukyus)

*Sophie Debaecker¹, Nathalie Feuillet², Kenji Satake³, Kohki Sowa⁴, Masaki Yamada⁵, Tetsuro Sato⁶, Atsushi Watanabe³, Ayaka Saiki³, Jean-Marie Saurel², Mamoru Nakamura⁷, Giovanni Occhipinti², Tsai-Luen Yu^8,9, Chuan-Chou Shen^8,9 (1.Littoral Environnement et Societes (LIENSs), UMR 7266 CNRS, La Rochelle Université, La Rochelle, France, 2.Institut de Physique du Globe de Paris, Université de Paris, Paris, France, 3.Earthquake Research Institute, The University of Tokyo, Tokyo, Japan, 4.Ministry of the Environment, Japan, 5.Department of Geology, Faculty of Science, Shinshu University, Matsumoto, Japan, 6.Department of Earth Sciences, School of Education, Waseda University, Tokyo, Japan, 7.University of the Ryukyu, Okinawa, Japan, 8.National Taiwan University, High-Precision Mass Spectrometry and Environment Change Laboratory (HISPEC), Taipei, Taiwan ROC, 9.National Taiwan University, Research Center for Future Earth, Taipei, Taiwan ROC)