The 7.8 magnitude Nepal earthquake on April 25, 2015 and subsequent aftershocks caused more than 8,500 fatalities, nearly 22,500 injured, and damaged thousands of buildings. The powerful quake also left potential secondary hazard risk from landslides and glacial lake outbursts threatening the lives and livelihood of people living the mountainous region. Langtang Valley was one of the worst hit by the earthquake, when a massive snow and ice avalanche triggered by the quake swept the entire valley leaving few survivors.

ICIMOD researchers visited Langtang Valley on 12 May and again 4-9 June to assess geo-hazards in the area and to determine the status of research stations located there. Seven out of eight meteorological stations operated by ICIMOD and its partners were found to be substantially damaged. A task force of ICIMOD researchers is working with NASA to assess landslide and river blockage in the earthquake affected area.

The task force found that in the aftermath of the earthquake, villages in the Langtang valley were destroyed by a combination of air blasts sweeping down the steep slopes of the valley, landslides, and avalanches. The avalanches made of snow and ice mixed with rock material accelerated on the way down the steep valley slopes, displacing the air to create a strong air blast. As a result the eight highest villages in the Langtang Valley — Thyangshyup, Tsarding, Chamki, Gumba, Langtang, Mundu, Singdum, and Kyangjing — were completely destroyed and buried under the avalanche debris. Early analysis of photographs and satellite imagery suggests the size of the avalanches was due in part to debris and ice accumulation above Langtang Village at 4500 meters through small ice avalanches and rock fall from Langtang-Lirung.

The Task Force continues to study and analyse the destruction in Langtang caused by the earthquake and the subsequent avalanches, landslides, and pressure waves to evaluate and map hazards in the future.

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