Proglacial lake development and outburst flood hazard at Fjallsjökull glacier, southeast Iceland

A significant expansion of Fjallsárlón proglacial lake, fed by Fjallsjökull glacier in Vatnajökull National Park, is projected if current retreat rates persist. By 2110, the lake could more than double in surface area and triple in volume, occupying two overdeepened basins with a maximum depth of ~210 m. This expansion may accelerate glacier melting and calving, potentially floating the glacier tongue. The study also identifies three high-risk zones on valley walls where rockfalls or avalanches could trigger displacement waves or glacial lake outburst floods (GLOFs), posing hazards to visitors and infrastructure. Using multibeam sonar surveys, researchers mapped lake development from 1945 to 2021, providing critical data for risk assessment and mitigation strategies at this UNESCO World Heritage Site.

Wells, G. H., Sæmundsson, Þ., Pálsson, F., Aðalgeirsdóttir, G., Magnússon, E., Hermanns, R. L., & Guðmundsson, S. (2025). Proglacial lake development and outburst flood hazard at Fjallsjökull glacier, southeast Iceland. Natural Hazards and Earth System Sciences, 25(6), 1913–1936. https://doi.org/10.5194/nhess-25-1913-2025