• Glacial lake outburst floods (GLOFs) occur from an unstable natural dam formed from a glacial retreat.
• Glaciers are large bodies of ice moving slowly. So, when a glacier retreats, it leaves behind a large impression in the ground,        filling it with water and a lake is formed.
• This is known as a moraine, which can be impounded by precarious pile of debris and buried ice
• The moraine dammed lakes weaken as the water level rises and the glacier retreats
• They might crumble under pressure from the swelling lake, leading to massive floods

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• Glacial lakes may vary in volume but may hold millions to hundreds of millions of cubic metre of water, say experts.
• The outburst of water can also happen due to erosion, an avalanche of snow or rock, an earthquake or volcanic eruptions under the ice.
• A moraine-dammed lake forms as a glacier retreats, and meltwater fills the space between the proglacial moraine (in front of the glacier) and the retreating glacier
• In the Hindu Kush Himalaya, moraine-dammed glacial lakes are common and numerous GLOF events have been traced back to the failure of moraine dams