Do gas fluxes from numerical modeling and from field data match ?

Modeling magma ascent within volcanic conduits is not an easy task since it involves complex physical interactions between melt, crystals and gas. Since the evolution of gas content mainly controls the eruptive dynamics, we have to do our best to understand and quantify how and when this gas phase exsolves from the melt, expands and finds its way toward the surface, possibly independently from the melt. In order to follow these phenomena with time, we developed a new 1.5D two-phase system which takes, among others, effects of pressure, temperature, volatile exchanges (including diffusion and viscous relaxation) between the melt and gas phases into account. First tests with this numerical model have then been conduced in order to see if we manage to reproduce gas content and gas fluxes prior to the July 2013 vulcanian eruption at Tungurahua volcano in Ecuador.