A Beijing-backed geological study has raised fresh concerns about the structural safety of China's under-construction mega hydropower project on the Yarlung Tsangpo River in Tibet, identifying an active fault line beneath the site that could pose risks to the dam's long-term stability.
The project, located around 50 kilometres from the Indian border, is set to become the world's largest hydroelectric dam.
It has already drawn concerns from India and Bangladesh over its potential impact on downstream water flow and the environment, as the Yarlung Tsangpo flows into India as the Brahmaputra River before entering Bangladesh as the Jamuna.
According to the study, published last month in the Chinese-language journal Sedimentary Geology and Tethyan Geology and supervised by the state-owned China Geological Survey, the Paizhen Fault passes directly beneath the reservoir area of the project.
Researchers said the fault has remained active since the Pleistocene, or Ice Age, and could threaten the structural integrity of dams, bridges, tunnels, roads and other infrastructure in the region. They noted that the fault has fractured surrounding rock formations, weakening their mechanical properties and reducing the stability of foundations.
The study also warned that the reservoir area consists of loose geological formations with weak cohesion. Combined with fault movement, earthquakes, and prolonged water exposure, these conditions could increase the risk of landslides and slope failures around the reservoir.
Construction of the Yarlung Tsangpo hydropower project began last year. Once completed, it is expected to generate around 300 billion kilowatt-hours of electricity annually, nearly three times the generating capacity of China's Three Gorges Dam.
The researchers cited geological evidence showing that the Paizhen Fault remained active into the Holocene period, with movement recorded as recently as 9,500 years ago. They also pointed to the magnitude 6.9 Milin earthquake that struck Tibet in 2017 near the northern end of the fault as evidence of the region's continuing seismic activity.
Warning that future earthquakes could trigger landslides and endanger both infrastructure and personnel, the study recommends engineering measures such as slope reinforcement and retaining barriers to improve the stability of the project during construction and operation.