Glacier Collapse Likely Triggered Nepal-Tibet Floods, Experts Say

A catastrophic glacier collapse in the mountains of Nepal, near the Tibetan border, is the likely cause of the devastating floods that have impacted both regions. Experts believe a massive chunk of ice, estimated to be between half a million and tens of millions of cubic meters, detached from an altitude of approximately 5,200 meters.

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A large chunk of glacier fell from about 5,200 metres... into a valley.

This colossal ice fall transformed into a "raging mass of debris" as it plunged into the valley below. Simon Cox, principal scientist at New Zealand's GNS Science, described how the debris flow "picks up rocks and sediment and trees and anything in the way and fires it on down through the canyon." The initial impact was documented on terrifying CCTV footage, showing mud and debris engulfing a border post as people fled.

The wall of water then surged downstream into Nepal, causing widespread destruction. Villages were flooded, and numerous bridges and buildings were swept away. The sheer scale of the glacier collapse was significant enough to register as a seismic event, initially leading to confusion and speculation that an earthquake had occurred. However, the U.S. Geological Survey later determined the seismic activity was caused by the glacial collapse and debris flow.

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It "transformed into this raging mass of debris... where it picks up rocks and sediment and trees and anything in the way and fires it on down through the canyon."

With the affected area largely inaccessible, scientists are employing advanced methods to understand the disaster. Glaciologists like Lauren Vargo from New Zealand's Victoria University of Wellington are analyzing satellite imagery taken before and after the event to identify changes and determine the extent of the missing ice. This detective work is crucial for reconstructing the sequence of events and assessing the risks associated with similar phenomena.

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that the seismic event was instead a glacial collapse and debris flow, and that no earthquake had occurred.

Early theories had suggested a glacial lake outburst flood (GLOF), a growing concern due to climate change-induced glacier melt. While water flow within and beneath glaciers is common, the sudden release of a large volume of water down a valley points towards a collapse event. Adrian McCallum, a glaciologist at the University of the Sunshine Coast, noted that such an event would require a release mechanism, reinforcing the glacier collapse theory.

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We can look at satellite imagery taken before and after the event, and try and see what has changed, essentially looking for what is missing from the mountains in the 'after' imagery.