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CO2 diffuse degassing in volcanic lakes in Ecuador

Daniel Sierra1, Silvana Hidalgo 1, Marco Almeida1, Diego Narvaez2, Jean Battaglia3, Pablo Samaniego3

  • Affiliations:  1 Instituto Geofísico, Escuela Politécnica Nacional, Quito-Ecuador; 2 Departamento de Geología, Escuela Politécnica Nacional, Quito-Ecuador; 3 Université Clermont Auvergne, CNRS, IRD, OPGC, Laboratoire Magmas et Volcans, Clermont-Ferrand, France. 

  • Presentation type: Poster

  • Presentation time: Friday 16:30 - 18:00, Room Poster Hall

  • Poster Board Number: 88

  • Programme No: 6.8.14

  • Theme 6 > Session 8

Abstract

Active volcanic lakes pose the hazard of limnic eruptions as water can retain volcanic gases and suddenly release them during quiescent periods. Cuicocha and Quilotoa, Ecuador, are volcanic lakes whose last eruptions occurred 3000- and 800-years BP, respectively. Both are surrounded by inhabited areas and are important touristic sites in the country. At Quilotoa, a limnic eruption killing all the cattle grazing inside the crater is described in the historical chronicles. This event occurred in 1797 and is related to the Riobamba earthquake (Mic 7.6, about 100 km to the south). In order to identify seasonal patterns and to evaluate the potential hazard of occurrence of limnic eruptions, we perform periodic diffused CO2 surveys using the accumulation chamber method at both lakes. The diffused CO2 emissions at Cuicocha have been measured for more than a decade, revealing strong spatial and seasonal control in the degassing process. CO2 for Cuicocha is of 34 g/m2/d, with some values reaching up to 63 g/m2/d. For Quilotoa, CO2 emissions have been measured five times between 2014 and 2018, showing values ranging from 46 to 180 g/m2/d. Recent measurements, during 2024, reveal fluxes of up to 110 g/m2/d which are significantly higher than the average reported for Cuicocha. Interestingly, these values are also much higher than those measured at lake Nyos (~8 g/m2/d), where a catastrophic limnic eruption caused about 1500 casualties in1986. A better understanding of the CO2-degassing dynamics at both lakes, will enhance the ability to forecast these hazardous phenomena in the future.