The causes behind the massive floods and landslides in Nepal and the Tibet Autonomous Region of China are gradually coming to light.

Based on satellite imagery, scientists believe that a collapse of rock formations in the mountains of the affected region, which sent massive amounts of rock and glaciers cascading down, likely triggered this disaster.

According to AP and Bloomberg on the 28th (local time), geologists analyzing satellite imagery confirmed that bedrock beneath a glacier near the Langtang Lirung peak in the border area between Nepal's Bagmati Province and China's Tibet collapsed, sweeping away massive blocks of ice and dumping rocks and ice into the valley.

Dan Shugar, an associate professor of geoscience at the University of Calgary in Canada, stated, "The images gave us an unvarnished view of the entire area, showing that it wasn't just a glacier collapse, but a much larger part of the mountainside bedrock that failed. It was a massive rock avalanche accompanied by parts of a glacier."

He explained that as a result, a massive amount of ice from an altitude of about 5,200 meters broke off and began a steep descent toward the valley floor, during which the ice melted and swept sediment along with it.

This ice and falling rock blocked the Lende Khola River, a tributary of the Bhotekoshi River, causing water levels to rise rapidly before ultimately rushing downstream.

"When a massive amount of rock falls from a high elevation, a lot of heat is generated, which can melt a large volume of ice," Shugar said. "Therefore, some of the water visible in those horrifying videos can be accounted for by this phenomenon."

Simon Allen, a researcher of glacier-related hazards at the University of Zurich in Switzerland, also stated that preliminary analysis of satellite and field images indicated a collapse of the bedrock beneath the glacier.

"What we can confirm for sure is that a massive ice avalanche occurred," Allen said. "It seems a mixture of ice and rock broke off, became fluid, and ultimately transformed into a destructive flood."

Christine Cook, a geologist at Université Grenoble Alpes in France, said satellite images of the lower reaches of the Lende Khola River show that the river water became choked with sediment such as mud, causing the river to widen significantly and its color to shift from green initially to brown and black.

Consequently, villages situated along the lower riverbanks, such as Betrawati and Kolpurtar, appear as brown zones covered in mud in satellite images, with only the roofs of some houses barely visible, Cook reported.

Alton Byers, a senior research associate at the University of Colorado Boulder in the United States, explained that climate change is melting glaciers and permafrost, destabilizing slopes and triggering massive collapses of snow and ice from high altitudes.

"All indicators point to the influence of global warming trends," he noted. "In this case, the permafrost that had firmly held together rock, ice, soil, and glaciers at high altitudes for thousands of years is now weakening and destabilizing."

Byers, a Nepal glacier disaster expert, stated that this flood is by far the largest glacier-related flood he has witnessed, and expressed concern that it will take years for the devastated region to recover.

According to the governments of Nepal and China, the total death toll from the disaster that occurred on the 26th stands at 392 across both countries, with the number of missing totaling 1,468.

(Photo: AP, Yonhap News)