Analysis of short and long-term sulfur dioxide degassing and seismicity from active volcanoes in Guatemala

Abstract

During the last decade, volcanic activity in Guatemala has been intense, and the most significant eruptions have occurred in its most active volcanoes (e.g., Fuego 2012, 2015 to 2018; Santiaguito 2014; Pacaya 2014). Four field campaigns (2014-17) were conducted to obtain sulfur dioxide (SO2) gas emission data, using a mini-DOAS (2014-17) and a FLYSPEC (2015-17) system. These ground-based instruments take advantage of SO2's selective absorption of UV radiation, to produce SO2 column amounts in order to convert the product into emission rates. Additionally, seismic data were provided by the local monitoring institution, INSIVUMEH (National Institute of Seismology, Volcanology, Meteorology, and Hydrology), and other collaborators, with the purpose of correlating with SO2 gas emission data. Seismicity at volcanoes occurs during quiescent stages and explosive eruptions when, for example, magma and its volatile content interact with the rocks that surround it in the conduit. Throughout this research, SO2 gas data, from ground-based and satellite-based techniques, and seismic data were analyzed with the aim of making interpretations to understand the volcanic phenomena and eruptive activity changes. The results from the analysis of the ground-based data indicate that the highest SO2 emitter was Fuego with ~940 tonnes per day (t/d) in 2016. The highest daily fluxes measured at Pacaya were ~500 t/d in 2016, and at Santiaguito they were ~410 t/d in 2017. The available seismic data were processed and analyzed with respect to the period of study, looking at long-term relations with gas emissions and eruptive activity. Comparisons between short-term SO2 emissions and seismicity were made. The total annual contribution of SO2 to the atmosphere for Fuego, Pacaya, and Santiaguito during the study period was ~0.38 Tg/yr, which represents ~3% of the subaerial volcanic SO2 emissions.