Fig. 5

Estimated sound velocity inside the conduit above the magma surface. a Sound velocity inside the conduit above the magma surface depends both on the air temperature and the gas mass fraction (Morrissey and Chouet 2001). In this study, we considered these values to be 400–1300 K and 0.65–0.95, respectively, resulting in a range of 320–700 m/s (area within the black dashed line). b Probability density function of estimated sound velocity for a temperature range and gas mass fraction range of 400–1300 K and 0.65–0.95, respectively