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

• Published in: Journal of geophysical research. Solid earth 2022-11, Vol.127 (11), p.n/a
• Main Authors: Jiwani‐Brown, Elliot Amir, Planès, Thomas, Pacheco, Javier Francisco, Mora, Mauricio M., Lupi, Matteo
• Format: Article
• Language: English
• Subjects: Ambient noise; Anthropogenic factors; Broadband; Correlation analysis; Costa Rica; Crustal deformation; Deformation; Dispersion curve analysis; Fractures; Geophysics; Ground motion; Image processing; Image resolution; Instruments; Lava; Magma; magmatic reservoir; Mountains; Rayleigh waves; Reservoirs; Rock; Rocks; seismic ambient noise; Seismograms; Tectonics; Tomography; Transition points; Volcanic activity; volcanic arc; Volcanism; Volcanoes; Wave dispersion; Wave groups
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2022JB024575

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. Plain Language Summary The line of volcanoes running from Guatemala to Panama are interrupted briefly in Costa Rica at the two volcanoes, Irazú and Turrialba. Here is a transition point between the volcanoes and the Talamanca mountain range. We installed a series of instruments that measure ground motion, around Irazú and Turrialba volcanoes. We supplemented this with other stations belonging to Costa Rican monitoring institutes. From the data, we observe how energy travels through the ground in the form of ambient noise, produced by natural and anthropogenic sources. This noise changes when traveling through subsurface features such as magma or fractures in the rock. We create images of the subsurface of Central Costa Rica and the Irazú and Turrialba volcanoes. We find large volumes of semi‐liquid rock, possibly magma, surrounded by solid rock, beneath the volcanoes. Using the installed instruments, we improve the image resolution of the Irazú and Turrialba