Magmatic and Tectonic Domains of Central Costa Rica and the Irazú-Turrialba Volcanic Complex Revealed by Ambient Noise Tomography

Abstract

The Central America Volcanic Arc runs from Guatemala to Panama, locally interrupted in Costa Rica after the twin-system Irazú-Turrialba Volcanic Complex, at the onset of the Talamanca Cordillera. A marked geological discontinuity characterizes the transition between the volcanic arc and this continental mountain range. To shed light on the spatial and structural relationships between active tectonics and volcanism, we deployed a temporary network consisting of 20 broadband seismic stations around the Irazú-Turrialba Volcanic Complex that integrated the national seismic networks maintained by Costa Rican institutes. From the seismic records, we extract cross-correlation functions and Rayleigh wave group-velocity dispersion curves to perform two ambient noise tomographies at a regional and local scale. From this, we derive two models that point out the magmatic and tectonic features of the southern part of the Central American Volcanic Arc and of the Irazú-Turrialba Volcanic Complex. The regional-scale tomographic inversion suggests that such a volcanic complex shares a common reservoir at about 5–7 km depth that is fed by a sub-vertical region, departing from at least 12 km depth. From here magmas appear to be transported upwards and stored in separate reservoirs below each volcanic edifice. Our study establishes an improved understanding of the spatial relationship between tectonic features and distribution of magmatic reservoirs underpinning the plumbing system of the Irazú-Turrialba volcanic complex.