10:15 AM - 10:30 AM
[SVC39-06] The chemical composition of thermal waters from spring and hot pool at Mt. Iwoyama of Kirishima volcano
Keywords:Mt. Iwoyama of Kirishimayama volcano, Thermal water, Chemical composition
Between August 2016 to March 2018 (about a month before the eruption), the Cl/SO4 of the spring water increased from 0.07 to 0.9. About a month after the eruption, the ratio increased to 1.6 as of May 2018, and remain between 1.2 and 1.6 since then to January 2019.
Cl/SO4 molar ratio of hot water pool in one of the southern craters was 1.3 in May 2018 and 1.8-2.3 in January 2019. The ratio of hot water pool in the western crater was 1.3 in July 2018, 1.9 in October 2018 and 2.2 in January 2019. The increase of Cl/SO4 molar ratio may be caused by several reasons, for example, the ascent of volatile-rich magma or chemical composition change of volatiles along with the progress of degassing.