[1] Tohoku Univ, Grad Sch Sci, Dept Geophys, Aoba Ku, 6-3 Aramaki Aza Aoba, Sendai, Miyagi 9808578, Japan
[2] Kyoto Univ, Disaster Prevent Res Inst, Sakurajima Volcano Res Ctr, Kagoshima, Japan
[3] Ctr Volcanol & Geol Hazard Mitigat, Bandung, Indonesia
[4] Hokkaido Univ, Inst Seismol & Volcanol, Grad Sch Sci, Sapporo, Hokkaido, Japan
[5] Univ Firenze, Dipartimento Sci Terra, Florence, Italy