Spatiotemporal deformation and activity distribution of Irazú and Turrialba volcanoes, Costa Rica: Are these volcanoes interconnected?

Abstract

The spatiotemporal distribution of volcanic activity poses a significant challenge to risk mitigation measures, as it is still largely unexplored in most of the volcanic systems. In this study, we re-assess the deformation observed by leveling surveys covering the nationwide tragedy 1963–1965 Irazú eruption in Costa Rica with a state-of-the-art analytical source inversion model. We combine the analytical model results with recent geophysical, geochemical, and petrology data to build a geological model of Irazú and its 10 km-distant Turrialba volcano. Based on the leveling survey, the source inversion model finds a reservoir between 5 and 7 km below the Irazú crater which is deeper than previously published. We also confirm that the source location is on top of the mid-crustal reservoir that was feeding Turrialba between the 2010–2022 eruptions. Using previous seismic tomography, gravity, petrology, and geochemistry study of Turrialba and Irazú, as well as other studies conducted on nearby volcanoes worldwide, we find that Irazú and Turrialba volcanoes likely share a mid-crustal plumbing system which could suggesting that their plumbing systems are interconnected with each other. These findings have important implications on the spatiotemporal distribution of the volcanic activity and for the 2.8 million inhabitants settled within a 50 km radius. Observations during recent episodes indicates that inflation beneath Irazú has the potential to trigger eruptive activity at either Irazú or Turrialba. While further analysis is required to assess the tectonic control on volcanic activity, tectonic processes may shape both short- and long-term volcanic activity. These results have global implications for risk mitigation measures for nearby volcanoes.