Heat and fluid flow dynamics of a stratovolcano: The Tacaná Volcanic Complex, Mexico-Guatemala

Abstract

Mexico is the world's sixth-largest geothermal energy producer. To pursue its transition to renewable energy, other potential geothermal areas are under exploration. The Tacaná hydrothermal system is one of them. In this work, we developed a preliminary 2D numerical mass and heat flow model of the natural state of the Tacaná volcano in order to gain insight into fluid and rock properties at depth. A comprehensive set of simulations was performed involving various rock permeabilities, geometries, and upper and basal boundary conditions until the simulated data matched the measured data, including spring and fumarole temperatures at the surface and thermal spring discharge. Simulation results show that the temperature structure and the phase distribution at depth are partly controlled by the permeability distribution inside the volcano together with a low topography-driven downflow and the absence of elevated fluid pressures at shallow levels. The low topography-driven recharge may be related to a low-permeability layer, whereas low fluid pressures most probably related to a relatively deep water table. The deep thermal fluid source must be connected to the San Antonio fumarolic field by a high-permeability conduit to enhance the fluid upflow and the development of a boiling zone in the uppermost part of the cone. Furthermore, our results suggest that the (almost) total absence of hydrothermal manifestation in the NE part (Guatemala) of the volcano is controlled by the tilting of the basement rocks. Our model will be used as initial conditions for the modelling of several geothermal exploitation scenarios in future work.