Hazards of volcanic lakes: analysis of Lakes Quilotoa and Cuicocha, Ecuador

摘要

Volcanic lakes within calderas should be viewed as high-risk systems, and anintensive lake monitoring must be carried out to evaluate the hazard ofpotential limnic or phreatic-magmatic eruptions. In Ecuador, two calderalakes – Lakes Quilotoa and Cuicocha, located in the high Andean region>3000 a.s.l. – have been the focus of these investigations. Both volcanoesare geologically young or historically active, and have formed large anddeep calderas with lakes of 2 to 3 km in diameter, and 248 and 148 m indepth, respectively. In both lakes, visible gas emissions of CO₂ occur,and an accumulation of CO₂ in the deep water body must be taken intoaccount.Investigations were carried out to evaluate the hazards of these volcaniclakes, and in Lake Cuicocha intensive monitoring was carried out for theevaluation of possible renewed volcanic activities. At Lake Quilotoa, alimnic eruption and diffuse CO₂ degassing at the lake surface are to beexpected, while at Lake Cuicocha, an increased risk of a phreatic-magmaticeruption exists.