Earthquakes may not be primary driver of glacial lake outburst floods
Glacial lakes form when meltwater is trapped behind a dam, usually glacial ice, bedrock or a type of moraine (terminal types being an unconsolidated pile of debris at the maximum extent of the glacier). When a dam fails, the resulting sudden release of a large volume of water is known as an outburst flood, having catastrophic consequences on the environment and communities downstream.
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Dr. Joanne Wood, a Postdoctoral Research Fellow at the University of Exeter, and colleagues investigated glacial lakes in the tropical Peruvian and Bolivian Andes, South America, and the record of outburst events associated with earthquakes. They found that of 59 earthquakes occurring between 1900 and 2021 near glacial lakes, only one resulted in an outburst flood.
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Considering the 1970 anomaly once more, Dr. Wood and colleagues suggest that this earthquake triggered thousands of rockfalls, rockslides and soilslides into lakes across three valleys comprised of deeply weathered granitoids that had been destabilized by frost wedging. This is the process by which water flows into cracks, freezes and causes expansion, thus opening the crack further.
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