The nature and source of the volcanic ash during the 2015 small phreatic eruption at Hakone volcano, central Japan

摘要

On June 29, 2015, a small phreatic eruption occurred in the Owakudani geothermal area on Hakone volcano, central Japan. Ashfall was observed on June 29 and 30. In this study, constituent minerals, whole-rock composition, and watersoluble components of the ash sampled at the Owakudani geothermal area on June 30 were analyzed to determine the source depth and hydrothermal condition of this ash.