*Vico Luthfi Ipmawan^1,2,4、Masato Iguchi²、Takahiro Ohkura³、Takeshi Tameguri¹ (1.Earth and Planetary Science Division, Graduate School of Science, Kyoto University、2.Sakurajima Volcano Research Center, Disaster Prevention Research Institute, Kyoto University、3.Aso Volcanological Laboratory, Institute for Geothermal Sciences, Graduate School of Science, Kyoto University、4.Physics Department, Institut Teknologi Sumatera)