Detection and analysis of GLOF events at Alemania (Roncagli) Glacier, Cordillera Darwin

The rapid retreat of glaciers due to warmer temperatures has resulted in an increase in both number, size and volume of glacial lakes across the Andes. Indeed, a recent study found that Patagonian lakes have more than doubled in volume during the last three decades. These lakes, constrained by unstable moraine dams or ice walls, hold the potential for catastrophic outbursts, known as Glacial Lakes Outburst Flood (GLOF) events. Glacial inventories are available since 1986 for Central Andes, Northern Patagonia and Southern Patagonia and GLOF occurrence and distribution has been widely studied for Chilean and Argentinian Andes. However, very few information on glacial lakes and related GLOF events exists in the Cordillera Darwin. Although the sudden release of immense volumes of water, sediments, and debris in such a remote area does not have the potential of affecting communities and infrastructures downstream, as in more populated areas, it still poses severe threats to the fiords ecosystems. Here we present the detection and analysis of a GLOF event at Alemania (Roncagli) glacier, in the south-western flank of the Cordillera Darwin, occurred in April 2023. The GLOF event was initially identified through FerryBox data collected across the Beagle Channel and subsequently confirmed using satellite imagery, analysing changes in the area of Lake Martinic, where the secondary front of Alemania glacier terminates. Moreover, a detailed analysis of 35 satellite images reveals a regular occurrence of such events since 2018, emphasising the repetitive nature of GLOFs at Alemania Glacier and its potential of disrupting the Beagle Channel ecosystem.