[S-VC42] Hydrothermal systems of volcanoes

[SVC42-09] Some of the recent findings in shallow hydrothermal system beneath Ebino Highland adjacent to Iwo-Yama, Kirishima Volcanoes

*Yoshikazu Kikawada¹, Wei Deng¹, Kaishu Seki¹, Megumi Fukai¹ (1.Faculty of Science and Technology, Sophia University)

Keywords:Kirishima Volcanoes, Iwo-Yama, Ebino Highland, Hydrogen sulfide

Iwo-Yama volcano belonging to the Kirishima Volcanic Complex (the Kirishima Volcanoes) is one of the active volcanoes in Japan. Ebino Highland adjacent to the volcano had been known as a tourist destination with a fumarolic area. In December 2015, fumaroles were found at the crater of Iwo-Yama after twelve year’s absence, and an expansion of thermal and fumarolic activities have been observed around its summit area and Ebino Highland since then. Meanwhile, thermal springs were also found along a stream in the highland. The changes in the water chemistry of those thermal springs seem to be in good accordance with the seismic activity and deformation observed around Iwo-Yama. The fluctuation of the content of dissolved H₂S in the spring water and the atmospheric concentration of H₂S and CO₂ at the water vents suggest that the spring water is an efficient carrier of the volatiles do not dissolve readily in water originated from the hydrothermal reservoirs beneath Ebino Highland.