2021 Chamoli disaster triggered by massive rock and ice avalanche

An avalanche of rock and ice triggered the February 2021 Chamoli disaster, setting off a chain of events that severely damaged two hydropower plants and left more than 200 people dead or missing in Uttarakhand, India, according to a new study. The findings highlight the increasing risk in the Himalayas due to increased climate warming and development. Tall, steep slopes and deep valleys can make seismically active mountainous regions like the Indian Himalaya prone to destructive and deadly natural disasters. In addition, human activities that intersect with the natural hazards of these areas, such as the development of hydropower infrastructure, can substantially increase the risk for nearby populations. Here, Dan Shugar and colleagues present an analysis of satellite imagery, seismic records, numerical model results and eyewitness videos to better understand the cascade of events that led to the Chamoli disaster. According to Shugar

et al.

, just before dawn on 7 February 2021, a massive avalanche – containing nearly 27 million cubic meters of rock and ice – cascaded from the steep northern face of Ronti Peak. As the avalanche tumbled down the valley, frictional heating melted nearly all of the ice contained therein, transforming it into an extraordinarily large, swift and powerful debris flow, which swept up boulders more than 20 meters in diameter and scoured the valley walls up to 220 meters above valley floors. Based on their analysis, the authors identified three primary drivers for the disaster’s severity; the exceptional height from which the avalanche fell, the ratio of rock to ice in the initial cascade and the unfortunate location of downstream hydroelectric infrastructure. “The disaster indicates that the long-term sustainability of planned hydroelectric power projects must account for both current and future social and environmental conditions while mitigating risks to infrastructure, personnel and downstream communities,” Shugar

et al.

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This part of information is sourced from https://www.eurekalert.org/pub_releases/2021-06/aaft-2cd060721.php