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The Himalayan Collision Zone
Where India drives into Asia, raising the world's highest mountains and its deadliest continental quakes
Mount Everest is made partly of seafloor. Limestone near its summit holds the fossils of marine creatures, lifted more than eight kilometers by the slow collision of India with Asia. That collision, under way for about 50 million years, is still pushing the Indian Plate north at several centimeters a year, crumpling the edge of Asia into the Himalayas and the Tibetan Plateau. It is the planet's grandest example of two continents meeting, and also among its most dangerous. Along a 2,400-kilometer front, the strain that builds mountains is released in great earthquakes that have killed tens of thousands of people in Nepal, India, Pakistan, and China within living memory.
The zone arcs about 2,400 kilometers from the Nanga Parbat massif in northern Pakistan to the Namcha Barwa massif in southeastern Tibet, where the Yarlung Tsangpo bends around the eastern end. India and Eurasia converge at roughly 40 to 50 millimeters a year, and about 20 millimeters of that is absorbed across the Himalaya itself. Most of it is taken up on the Main Himalayan Thrust, a gently dipping fault beneath the range that surfaces at its southern foot as the Main Frontal Thrust, where the mountains meet the Indo-Gangetic Plain. Behind the front, the Tibetan Plateau averages more than 4,500 meters and is stretching east to west, cut by north-south rifts and normal faults. Kathmandu, Thimphu, and Himalayan towns sit directly above the locked fault.
The largest earthquake recorded here, the magnitude 8.6 Assam–Tibet quake of August 15, 1950, struck the eastern end and killed thousands. The 1934 Nepal–Bihar earthquake, about magnitude 8, and the 2005 Kashmir earthquake, magnitude 7.6, which killed more than 80,000 people, show the hazard at both ends. The magnitude 7.8 Gorkha earthquake of April 25, 2015, killed nearly 9,000 people in Nepal and triggered avalanches on Everest, yet it released only part of the strain stored beneath central Nepal. On January 7, 2025, a magnitude 7.1 quake on a north-south normal fault near Tingri, north of Everest, killed at least 126 people by China's official count, with other reports higher. Geologists warn that long segments of the frontal thrust have not ruptured in centuries.