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Degassing Mechanisms: Rincón de la Vieja volcano, Costa Rica

Jessica Salas-Navarro1 , Alejandro Rodríguez2, Henriette Bakkar2, Christoph Kern3, J. Maarten de Moor2,4, John Stix1.

  • Affiliations: 1Department of Earth and Planetary Sciences, McGill University, Montreal, Canada; 2Observatorio Volcanológico y Sismológico de Costa Rica, Universidad Nacional de Costa Rica, Heredia, Costa Rica; 3U.S. Geological Survey, Cascades Volcano Observatory, Vancouver, WA, USA; 4Department of Earth and Planetary Sciences,  University of New Mexico, Albuquerque, USA.

  • Presentation type: Talk

  • Presentation time: Thursday 11:00 - 11:15, Room S160

  • Programme No: 3.14.3

  • Theme 3 > Session 14

Abstract

Rincón de la Vieja is currently Costa Rica's most active volcano, with hundreds of explosive eruptions annually. The high frequency of eruptions is a unique opportunity to study their trigger mechanisms. We present the first semi-continuous SO2 degassing time series for Rincón de la Vieja from 2022 to 2024 using two new scanning DOAS stations. The dataset shows a significant increase in SO2 flux over the study period, reaching a peak in late 2023 when the volcano alert level was raised from yellow to orange. During the study period, 567 eruptions were detected seismically and by infrasound and were associated with short-lived peaks in the SO2 flux. By combining SO2 flux measurements with seismic data, we distinguished and quantified explosive degassing from passive emissions. Over the 2-year period, a cumulative ~15 ktons of SO2 were emitted during explosive eruptions, accounting for only ~9.4% of the total SO2 emissions (~160 ktons). The explosive/total ratio increased from 2022 to 2023. At the end of 2023, this ratio decreased while the passive SO2 emissions reached its highest. This change in the degassing behavior suggests an opening of conduits in late 2023. Our results demonstrate that explosive eruptions at this volcano are driven by magmatic degassing and increase in frequency in response to magma intrusion and displacement of the hydrothermal system. We estimate that 0.015 km3 of magma was intruded in 2022-2024. This study highlights the importance of continuous ground-based monitoring to capture the complex dynamics of persistently active volcanoes.