A Three-Pronged Approach to Understanding a 1950s Glacial Flood

Global warming is melting glaciers, creating lakes behind unstable dams. When these dams break, it causes Glacial Lake Outburst Floods (GLOFs), which can be devastating. Scientists often rely on satellite images and river gauges to track these floods, but older events might be missed. At Grosse Glacier in Chilean Patagonia, a massive GLOF happened in the 1950s, before such tracking methods existed.To learn more about this event, researchers combined tree-ring analysis with geomorphic and aerial photo analyses. Disturbed tree rings showed that the flood happened in 1957, matching eyewitness reports and rainfall records. The flood left behind a wide breach in the frontal moraine and caused a lateral lake to disappear. Drone images and object-based image analysis helped identify boulders and estimate the flow direction in the floodplain, indicating a high-energy event. This multi-method approach offers valuable insights into the timing and impacts of past extreme events, essential for predicting future GLOF hazards in high-mountain environments.