Active fault under China's Brahmaputra dam raises new safety concerns

Beijing,UPDATED: Jul 12, 2026 20:32 IST

A study by Chinese geologists has found that an active fault line beneath China’s massive hydropower project on the Brahmaputra River in Tibet could affect the dam’s structural stability, raising fresh questions over Beijing’s repeated claims that the project would be safe and help prevent disasters in the region. The project is close to the Indian border in Arunachal Pradesh.

China formally began construction of the USD 167.8-billion dam on the Brahmaputra, which it calls the Yarlung Tsangpo, in Tibet last July. The project is expected to generate more than 300 billion kWh of electricity every year and meet the annual power needs of more than 300 million people. It is being built in a massive Himalayan gorge where the river makes a sharp U-turn before flowing into Arunachal Pradesh and later Bangladesh, despite major engineering challenges as the site lies on a tectonic plate boundary that sees frequent earthquakes.

According to the Hong Kong-based South China Morning Post, which reported on the findings on Thursday, the researchers said a fracture in the Earth’s crust in the eastern Himalayan region could significantly affect the structural integrity of the hydropower project’s infrastructure. In a paper published last month in the Chinese-language journal Sedimentary Geology and Tethyan Geology, and supervised by the state-owned China Geological Survey, the researchers said the Paizhen Fault, which has been highly active since the Pleistocene or 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." They said prolonged fault activity had fractured and weakened nearby rock formations, making the foundations and structural stability of engineering projects more vulnerable to damage. "The Paizhen area is located within the reservoir area of the Yarlung Tsangpo downstream hydropower station," the paper said.

The study was conducted by geologists from the 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, according to the South China Morning Post. The researchers said Pai, also called Paizhen, village in Tibet, where construction is under way, lies in the Himalayan seismic belt, one of the most earthquake-prone regions in China and nearby areas, where strong seismic activity has developed along the Yarlung Tsangpo. They cited the magnitude 6.9 earthquake that struck Milin in Tibet in 2017 near the northern end of the fault as evidence that the fault remains seismically active. "Under regional seismic action, landslides and collapses can easily be induced, threatening the safety of engineering facilities and personnel," they said. The researchers urged engineers to reinforce vulnerable slopes and install retaining structures to reduce the risk of landslides and collapses. They also said, "Its records of Quaternary tectonic activity provide an important basis for exploring the structural stability of nearby projects." The paper said the Paizhen Fault is part of a network of faults in the eastern Himalayan region created by the collision of the Indian and Eurasian tectonic plates, and has remained active since the Early Pleistocene. It continues to show strong activity in the present Holocene epoch, with dating of ancient lake sediments suggesting it was active as recently as 9,500 years ago.

China has consistently tried to allay concerns over the project’s safety. An official statement issued in December 2024 said the hydropower project was safe and gave priority to ecological protection. "Through extensive geological explorations and technical advancements, a solid foundation has been laid for the science-based, secure, and high-quality development of the project," it said. In July last year, a Chinese Foreign Ministry spokesperson said China was highly responsible in developing cross-border rivers and had rich experience in building hydropower projects. The spokesperson said China had strictly followed the highest industry standards in planning, designing and constructing the project in the lower reaches of the river while protecting the ecological environment in an all-round way. He also said the project would help prevent disasters along the river and would not have a negative impact on downstream regions.

The Brahmaputra flows across the Tibetan Plateau, often described as the "roof of the world", carving out the world’s deepest canyon before entering India. While China has maintained that the project meets the highest standards and will not harm downstream areas, the new study says the active Paizhen Fault could affect the structural stability of the dam and other nearby infrastructure.

With PTI Inputs

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