Tsukasa Kobayashi¹, Koji Kato², Ryohei Kawaguchi³, Yusuke Yoshigai⁴, Yasuo Ogawa⁵, Kenji Nogami⁵, Wataru Kanda⁵ and Akihiko Terada⁶, (1)Volcanological Division, Japan Meteorological Agency, Chiyoda-ku, Japan, (2)Volcanological Division, Japan Meteorological Agency, Tokyo, Japan, (3)Meteorological Research Institute, Japan Meteorological Agency, Tsukuba, Japan, (4)Japan Meteorological Agency, Tokyo, Japan, (5)Volcanic Fluid Research Center, Tokyo Institute of Technology, Tokyo, Japan, (6)Volcanic Fluid Research Center, Tokyo Institute of Technology, Gunma, Japan