6 min learnNew DelhiUp to date: Aug 27, 2026 04:26 PM IST
Although scientists are nonetheless investigating the main points of Wednesday’s avalanche-induced flash floods in Nepal, it’s more and more wanting much like the 2021 occasion in Chamoli district of Uttarakhand, solely rather more highly effective.
“It appears to be similar to the Chamoli catastrophe, however when it comes to its affect downstream, and the destruction precipitated, it’s extra just like the Kedarnath occasion of 2013,” mentioned Farooq Azam, an affiliate professor at IIT Indore, at present heading the Cryosphere group on the Kathmandu-based The Worldwide Centre for Built-in Mountain Improvement (ICIMOD), a serious analysis organisation engaged on the Himalayas.
Chamoli and Kedarnath have been triggered by totally different mechanisms, each leading to largescale injury downstream. Kedarnath incident was initiated by what is called a GLOF occasion, a glacial lake outburst flood, through which lakes fashioned on the finish of a glacier overflow or breach their boundaries, resulting in a sudden launch of very giant volumes of water.
Chamoli, then again, was brought on by an ice and rock avalanche, a consequence of a giant ice-block of a glacier breaking away and falling downhill. Each occasions led to main surges in mountainous rivers and precipitated flash floods downstream.
“Wednesday’s incident within the Rasuwa district of Nepal appears to have been brought on by an ice and rock avalanche, probably triggered by an earthquake within the area. The ensuing injury is immense. A transparent evaluation of the extent of destruction will take a couple of days. However such occasions within the Himalayas do are inclined to develop into very damaging due to the cascading impacts downstream,” Azam, who’s at present in China attending a catastrophe threat discount convention, informed The Indian Specific.
The US Geological Survey had reported a 4.4 magnitude earthquake within the area, which was broadly believed to have triggered the landslide. Nevertheless, on Friday morning, the USGS up to date its report saying that the seismic power that was captured by its sensors was not generated by an earthquake however fairly by a glacial collapse and particles circulation.
“This occasion was initially reported as a magnitude 4.4 earthquake. Extra evaluation of close by seismic stations, lengthy interval seismic waves and satellite tv for pc imagery led to the dedication that the seismic occasion was as an alternative a glacial collapse and particles circulation, and that no earthquake had occurred,” USGS mentioned in its replace.
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That makes it much like the Chamoli catastrophe through which about 200 individuals have been believed to have been killed, lots of them staff at two hydroelectric energy tasks that got here in the way in which of the avalanche. The size of injury in Wednesday’s occasion in Nepal seems to be a lot greater, with a minimum of 1,500 individuals reported to be lacking as of Friday, aside from the 150 who’re identified to be killed. About 60-70 bridges have been swept away, and tons of of homes and different buildings have been destroyed.
Why the Nepal catastrophe could possibly be extra damaging than Chamoli
In a vital distinction, the Nepal catastrophe occurred throughout peak monsoon, when the rivers have already got a good quantity of water.
“Chamoli had occurred in February. However this one has come within the core monsoon season. The soil is already saturated, and many of the rivers are carrying waters close to their capability. Then there’s an occasion like this through which a big chunk of ice and snow and rocks fall off. It will create havoc,” Azam mentioned.
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“The Himalayan area could be very fragile. Such occasions result in a series response. A surging river with giant rocks and ice blocks would erode the banks and slopes, and extra soil, mud and rocks would develop into a part of the raging river. It turns into a cascading catastrophe as a result of the waters don’t have another option to unfold out. That’s the reason any such occasion within the Himalayan ecosystem turns into extraordinarily harmful,” he mentioned.
What the 2023 Sikkim floods reveal about cascading disasters
A research revealed in Science final yr a couple of 2023 occasion in Sikkim captured the cascading affect of such flash flood occasions within the mountains. This occasion was triggered by the collapse of a giant chunk of glacier into the South Lhonak lake, located over 5,000 meters above sea degree, in northern Sikkim. This led to a GLOF occasion, the sudden launch of a really giant quantity of water that took the form of flash floods downstream.
The research discovered {that a} landslide precipitated the collapse of practically 14.7 million cubic metres of rocks, soil and snow deposited round a glacier into the South Lhonak lake, which triggered a collection of cascading occasions. The amount of the flowing sediment downstream had grown to about 270 million cubic metres.
“The collapse of roughly 14.7 million cubic metres of frozen lateral moraine into the South Lhonak Lake … on 3 October 2023 generated a 20-m-high displacement wave. The wave overtopped and breached the frontal frozen moraine, inflicting the sudden drainage of roughly 50 million cubic metres of water… The GLOF eroded roughly 270 million cubic metres of sediment and triggered 45 secondary landslides. A lot of the erosion occurred inside about 67.5 km of the lake,” the research had discovered.
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The Nationwide Catastrophe Administration Authority has now initiated a complete train to review these glacial lakes with the target of strengthening their boundaries and putting in sensors that may warn of leakages and accumulation of water.
Azam mentioned your complete Himalayan area was “out of stability completely” due to inhabitants stress and local weather change.
“The entire ecosystem is susceptible. Due to local weather change and rising cases of utmost climate occasions, newer areas are getting uncovered. Earthquakes or heavy rainfall occasions are fairly widespread, and any of them can set off these sorts of disasters,” he mentioned.
