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Anomalous Diffuse CO2 Emissions at the Masaya Volcano (Nicaragua) Related to Seismic-Volcanic Unrest |
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| Authors: | Germán D Padilla Pedro A Hernández Nemesio M Pérez Ernesto Pereda Eleazar Padrón Gladys Melián José Barrancos Fátima Rodríguez Samara Dionis David Calvo Martha Herrera Wilfried Strauch Angélica Muñoz |
| Institution: | 1. Environmental Research Division, ITER, Polígono Industrial de Granadilla, 38611 Granadilla de Abona, S/C de Tenerife, Canary Islands, Spain 2. Instituto Volcanológico de Canarias (INVOLCAN), 38400 Puerto de la Cruz, Tenerife, Canary Islands, Spain 3. Department of Basic Physics and Mathematics, Universidad de la Laguna, Avda. Astrofísico Fco. Sánchez s/n, 38205, La Laguna, Spain 4. Dirección General de Geofísica, Instituto Nicaragüense de Estudios Territoriales (INETER), 1761, Managua, Nicaragua 5. Scientific-technical Area, Coordination Centre for the Prevention of Natural Disaster in Central America (CEPREDENAC), Managua, Nicaragua |
| Abstract: | Anomalous changes in the diffuse emission of carbon dioxide within the Masaya caldera have been observed before two seismic events that occurred at 10 and 30 km from the observation site. Their epicenters are located, respectively, south of Managua in Las Colinas (4.3 magnitude) and the Xiloa caldera (3.6 magnitude), in 2002 and 2003, recorded by the geochemical station located at El Comalito, Masaya volcano (Nicaragua). Anomalous increases were observed, which occurred around 50 and 8 days before the main seismic event that took place in Las Colinas, and 4 days before the seismic swarm at the Xiloa caldera, with a maximum CO2 efflux of 9.3 and 10.7 kg m?2 day?1, respectively. The anomalous CO2 efflux increases remained after filtering with multiple regression analysis was applied to the CO2 efflux time series, which indicated that atmospheric variables, during the first 4 months, explained 23 % CO2 variability, whereas, during the rest of the time series, CO2 efflux values are poorly controlled with only 6 %. The observed anomalies of the diffuse CO2 emission rate might be related to pressure changes within the volcanic–hydrothermal system and/or to geostructural changes in the crust due to stress/strain changes caused before and during the earthquakes’ formation, and seem not to be related to the activity of the main crater of Masaya volcano. |
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