A catastrophic event in Nepal, involving a collapsing glacier in Tibet, has resulted in significant loss of life and widespread destruction. The disaster, which sent a powerful surge of water and debris through a valley, is being studied by international experts to better understand the mechanics of such hazard cascades.
Stuart Dunning, a professor of applied geomorphology, describes the event as a rock-ice avalanche that originated at an elevation of approximately 4,800 meters. The mass fell over 1,200 meters, gaining momentum and volume as it eroded the valley floor and sides. Unlike a dry rock avalanche, the presence of ice allowed the material to liquefy, creating a long-runout debris flow that proved far more destructive.
While initial reports sometimes categorize such events as glacial lake outburst floods (GLOFs), experts note that no lake was involved in this specific instance. Instead, researchers are classifying it as a "hazard cascade" or "process chain." The exact trigger remains under investigation, with possibilities including a bedrock landslide that either carried the glacier with it or destabilized it shortly before failure.
Climate change is identified as a contributing factor, as thinning ice and thawing permafrost—which acts as a stabilizing "glue" for bedrock—increase the instability of Himalayan slopes. These environmental shifts, combined with the fact that more people now inhabit these high-mountain landscapes than in the past, have heightened the impact of such rare, extreme events.
Mitigating these risks remains a significant challenge. Unlike GLOFs, where the source and potential path can be modeled, landslides of this nature are difficult to predict or monitor across thousands of slopes. While local authorities utilized existing water-level gauges to issue alerts, experts emphasize that developing clear, actionable safety protocols for residents—such as determining when to seek shelter in concrete structures versus moving to higher ground—is essential for future disaster reduction.
Source: The Conversation
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