Even as China races to build the world’s largest hydropower project on the Yarlung Tsangpo River in Tibet, its own government-backed geologists have warned that the mega dam sits above an active fault line capable of triggering landslides, earthquakes and structural instability. The findings have renewed concerns not only over the safety of the project itself but also over its wider implications for India, where the river flows as the Brahmaputra and sustains millions of people before entering Bangladesh.The warning comes at a time when Beijing’s massive dam project has already become a geopolitical flashpoint. India has repeatedly expressed concerns over China’s upstream activities on the Brahmaputra, citing potential risks to water security, ecology and downstream communities. The latest study now raises fresh questions over whether the project also carries significant geological risks acknowledged by Chinese scientists themselves.According to a paper published last month in the Chinese-language journal Sedimentary Geology and Tethyan Geology, supervised by the state-owned China Geological Survey, the Paizhen Fault runs directly through the area where the hydropower project is being constructed.The study was carried out by researchers from Chengdu University of Technology, the Civil-Military Integration Centre of the China Geological Survey and the Middle Yarlung Zangbo River Natural Resources Observation and Research Station.“The Paizhen Fault, which has been highly active since the Pleistocene [also known as the Ice Age], will have a major impact on the structural stability and construction of nearby structures, including dams, roads, bridges and tunnels, as well as the reservoir area,” the researchers wrote.They said the fault has fractured surrounding rocks and weakened their mechanical properties, making engineering structures more vulnerable.“This makes the foundation bearing capacity and structural stability of nearby engineering projects more susceptible to damage.”The researchers further warned that the terrain surrounding the reservoir has a “loose structure and weak cohesion”, increasing the likelihood of major slope failures.“After long-term immersion and under the influence of fault activity and earthquakes, instability of the slopes on both sides of the reservoir area can be extremely easily triggered.”The dam, construction of which began last year, is designed to generate around 300 billion kilowatt-hours of electricity annually, roughly three times the capacity of the Three Gorges Dam. It is located on the Yarlung Tsangpo, which becomes the Brahmaputra after entering India’s Arunachal Pradesh before flowing through Assam and eventually Bangladesh.For India, the significance extends well beyond engineering concerns. The Brahmaputra is among the country’s most important river systems, supporting agriculture, drinking water supplies, fisheries, hydropower generation and livelihoods across the Northeast. Any disruption to its flow or a major structural failure upstream could have serious downstream consequences.The study noted that the Paizhen region lies within one of the most seismically active belts in the Himalayas, where the Indian and Eurasian tectonic plates continue to collide.“Since the Pai village area is located within the construction zone of the Yarlung Tsangpo downstream hydropower project, its records of Quaternary tectonic activity provide an important basis for exploring the structural stability of nearby projects.”The researchers said geological evidence shows the fault has remained active from the Early Pleistocene through the present Holocene epoch, with sediment analysis indicating activity as recently as 9,500 years ago. They also cited the magnitude 6.9 earthquake that struck Milin in Tibet in 2017 as evidence that the fault continues to pose a real seismic threat.“Under regional seismic action, landslides and collapses can easily be induced, threatening the safety of engineering facilities and personnel,” they said.“During construction, structural stability safeguards must be strengthened. Implementing strategies such as slope reinforcement and retaining barriers is essential to mitigate the risks of landslides and collapse to construction and operation.”The findings are likely to strengthen India’s long-standing call for greater transparency and consultation over projects on transboundary rivers. While Beijing has maintained that the dam is intended primarily for hydropower generation, the admission by its own geologists that the project sits atop an active fault line adds a new layer of concern to a development that is as strategically significant as it is geologically sensitive.
