"We didn't even have time to evacuate."
It took a mere 7 minutes for debris flows and other hazards triggered by a glacier collapse in the Himalayas of Nepal—estimated to have originated at an altitude of about 5,200 to 5,540 meters—to pour down to a border port in the southern part of China's Xizang (Tibet) Autonomous Region.
According to China Central Television (CCTV) and local media outlets on the 28th, the Chengdu Institute of Mountain Hazards and Environment under the Chinese Academy of Sciences and the Ministry of Water Resources reached this conclusion after comprehensively analyzing satellite data, on-site footage, and meteorological data.
Nie Yong, a researcher at the institute, told the local media outlet Cover News, "This disaster was caused by the collapse of glaciers and rocks in the high-altitude glacial region of Nepal." He explained, "The collapsed glacier fell at an extremely high speed, melting into water from friction, which swept away glacial moraines as well as mud and sand from the river, forming a massive amount of debris flow."
China's Ministry of Natural Resources also explained that the landslide in Tibet, which left hundreds of people missing, was a "cascading disaster" triggered when a glacier collapsed in the highlands of Nepal and scraped away moraines and sediments in the valley, unleashing a debris flow.
With a massive volume of mud and rock sweeping in an instant, much like a tsunami hitting from the sea, heavy human casualties were inevitable.
As of the morning of the 27th, the death toll on the Tibet side stood at 3, with 558 people reported missing.
Nearly half of the missing persons, numbering 260, were classified as foreign nationals.
Guo Zhaocheng, director of the Geological Disaster Investigation and Monitoring Center at the China Aero Geophysical Survey and Remote Sensing Center for Land Resources, said, "According to calculations, the movement speed of the collapsed glacial debris flow that caused the debris flow reached 50 meters per second." He added, "Because the speed was so fast, people had no time to respond, and the affected range reached about 20 kilometers, making the disaster damage extremely severe."
This amounts to a staggering speed of 180 kilometers per hour, whereas debris flows from landslides typically caused by heavy rain are known to move at speeds of several tens of kilometers per hour.
In this case, the landslide occurred in the high-altitude Himalayas—often called the "Roof of the World"—resulting in an altitude difference of about 3,000 meters between the disaster site and the downstream area, which appears to have given it immense destructive power.
The area that took the direct hit is the Gyirong Port (Jilong Port), a China-Nepal border checkpoint located in Gyirong County, Xigaze, Tibet.
Although administratively part of the Tibet Autonomous Region, it is about 830 kilometers away from Lhasa, the center of Tibet, and is relatively close to Kathmandu, Nepal, at a distance of about 130 kilometers.
In the past, the Zhangmu Port was one of the main land trade routes connecting China and Nepal, but it had long been closed due to the impact of the 2015 Nepal earthquake.
Under these circumstances, the Gyirong Port grew in importance.
Over the past decade, logistics parks, freight yards, and parking lots have been built in the Gyirong Port area.
Naturally, the floating population also increased.
However, the Gyirong Port, developed as a gateway to South Asia under China's Belt and Road Initiative (connecting China, Central Asia, and Europe through land and maritime Silk Roads), has also been severely impacted by this natural disaster.
It is projected that complete recovery will take a considerable amount of time.
To travel from China to South Asia via Nepal, one must cross the Himalayas, and the terrain suitable for building transportation routes is known to be extremely limited.
Furthermore, the valleys and river basins where transportation routes can be constructed pose the problem of being vulnerable to glaciers and landslides.
Satellite photos released before and after the landslide by China's Ministry of Water Resources show buildings completely covered in mud and stripped of any visible trace.
In addition, a "barrier lake" formed as sediments blocked the waterway already holds 2 million cubic meters of water, and an additional 3 million cubic meters of water are expected to flow in due to weather forecasts predicting rain over the next three days.
Amid concerns over secondary damage such as additional collapses and downstream flooding, the issuance of travel permits for the border regions of Xigaze has been suspended as of 0:00 on the 28th.
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