This paper reports the outburst of Lago Greve, a large proglacial lake in Chilean Patagonia, between April and July 2020. The lake level dropped by 18.3 ± 1.2 m, and the area decreased by 14.5 ± 0.02 km², resulting in a total water discharge of 3.7 ± 0.2 km³. This is one of the largest glacial lake outbursts recorded during the satellite era. Satellite data suggest the collapse of a bump near the lake outlet triggered the event, initiating erosion of the outlet stream's bank and bed. Satellite gravimetry detected the event, though the mass change was inconsistent with the drained water mass. The study highlights the potential of satellite imagery, altimetry, photogrammetry, and gravimetry for observing lake outbursts.

Shuntaro Hata, Shin Sugiyama, Kosuke Heki