Fig. 9
![Fig. 9](http://media.springernature.com/full/springer-static/image/art%3A10.1186%2Fs40623-021-01475-4/MediaObjects/40623_2021_1475_Fig9_HTML.png)
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)