Massive ice avalanche likely triggered deadly Nepal-Tibet floods, scientists say

A catastrophic ice avalanche, involving a massive section of glacier breaking away and plummeting thousands of feet, is the leading preliminary cause of the devastating floods that struck the Nepal and Tibet border region, according to geologists and glaciologists. Satellite imagery reveals a glacier segment approximately 2,000 feet wide detaching at an altitude of around 17,000 feet and falling nearly 4,000 feet into the valley below.

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It looks like a glacier in the area basically snapped off in a clean break, allowing it to fall just over a vertical kilometer to the valley bottom.

Daniel Shugar, a geologist at the University of Calgary, described the event as a "clean break" of a glacier, resulting in an immense cascade of ice and water that surged through river valleys. This phenomenon, known as an ice avalanche, has left hundreds missing in both Nepal and Tibet. Simon Cook, a glaciologist at the University of Dundee, who analyzed the imagery with Shugar, noted the enormous potential energy released by the falling ice mass, which would have been pulverized into a dangerous, fast-moving slurry.

This event bears similarities to a 2021 glacier collapse in India's Uttarakhand state, which resulted in significant flooding and over 100 fatalities. The glacier break occurred roughly 40 miles north of Kathmandu, with the resulting flow moving northwest along the Bhote Koshi River, which forms part of the border between Nepal and Tibet.

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When it breaks off, the sheer force of the drop pounds the ice into a dangerous, fast-moving mix.

While the ice avalanche theory is strongly supported by initial evidence, scientists emphasize that it is premature to definitively pinpoint the cause. Other contributing factors may still be identified. Kristen Cook, a geomorphologist at Université Grenoble Alpes, analyzed local seismic data, observing a large signal indicating a sudden downhill movement followed by flooding. However, she stated that the signal did not resemble an earthquake, suggesting the landslide itself generated the seismic activity. The US Geological Survey initially registered a magnitude 4.4 earthquake but later revised its assessment, concluding the landslide was the source of the seismic signal.

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I see a signal that is quite large at the start of the event, but it does not look like an earthquake.