Numerical Modelling of Temperature Field by Using Seismic Tomography at the Tinguiririca Magmatic-Hydrothermal System, Chile

Local earthquake tomography (LET) is a useful method for understanding physical properties of the sub-surface, and particularly for magmatic-hydrothermal systems. The 3D P- and S-wave velocity model obtained with LET allows interpreting seismic velocity anomalies generally observed at shallow depths below active volcanic areas as country rock or cooled magma bodies, and low velocity anomalies interpreted as magma chambers and associated hydrothermal fluids, generally in the range of 8-15 km depth. Seismic velocities are used to infer thermo-physical properties through the thermo-viscoelasticity theory. Considering constitutive and field equations for a locally isotropic medium, and an initial uniform temperature governed by the geothermal gradient, 3D velocity model is used to obtain the distribution of temperature, density and phase content. We present preliminary results of temperature distribution obtained for the Tinguiririca Volcanic Complex, in Central Chile, Southern Andes. This temperature field use as an input a new 3D body wave velocity model obtained for this area. Body wave arrival times are associated with the 2010 temporary deployment of 16 continuous recording, three component seismic stations. Both, temperature field and LET, are used for identify the zones with different density and phase content, and delineate magma bodies allowing identify geothermal reservoirs and estimate the volume of eruptable magma and the geothermal potential associated to this system.