Fig. 9

Schematic diagram of the hydrothermal system associated with the 2018 MPCG eruption. HF clusters represent hypocenter distributions of high frequency volcanic–tectonic earthquakes. The depth of the self-sealed brittle–ductile transition zone is based on the hypocenter distribution (Figs. 5–7). 1 Matsunaga et al. (2020); 2 Tseng et al. (2020); 3 Yamada et al. (2021); 4 Ohba et al. (2019a, b); 5 Himematsu et al. (2020)