The earthquake's epicenter struck the Mishmi Hills in northeastern India, just northeast of the Mishmi Thrust Fault. Calculated magnitudes range from 8.6 to 8.8, making it the most powerful onshore earthquake in recorded history and the largest not associated with subduction. The rupture area covered approximately 30,000 square kilometers across the Abor and Mishmi Hills, an extent confirmed by satellite imagery of landslide scars. Aftershocks were numerous and severe, with many exceeding magnitude 6. The shaking triggered rockfalls across the forested Mishmi Hills, destroyed 70 villages in the Abor Hills with 156 casualties from landslides alone, and blocked tributaries of the Brahmaputra with debris dams that would prove lethal.

The earthquake's deadliest aftermath came not from shaking but from water. Landslides dammed the tributaries of the Brahmaputra, creating unstable lakes behind walls of debris. In the Dibang Valley, one landslide dam burst without causing damage. But eight days later, a dam on the Subansiri River gave way, unleashing a wall of water that submerged several villages and killed 532 people. Across Assam, rivers rose suddenly after the earthquake, carrying sand, mud, trees, and debris. Pilots flying over the epicentral area reported that the topography itself had changed, with enormous landslides visible from the air. The property damage in Assam exceeded even the devastating earthquake of 1897, a tremor that had remained the benchmark for seismic destruction in the region for half a century.

What made the 1950 earthquake distinctive beyond its magnitude was the sound. Kingdon-Ward, Harrer, Morse, and countless others described extraordinary noises emanating from the ground, as if the earth were cracking apart from within. These sounds were later investigated by seismologists as a notable phenomenon. Seiches, standing waves in enclosed bodies of water triggered by distant seismic energy, were observed as far away as Norway and England. One of the more westerly aftershocks, occurring days later, was actually felt more widely in Assam than the main shock, leading journalists to declare it the greatest earthquake of all time. Scientists noted this as a classic confusion between magnitude, which measures energy released, and intensity, which measures shaking at a particular location.

The 1950 earthquake was not an anomaly but a reminder. Field studies in the Burhi Dihing River Valley later uncovered signs of soil liquefaction, sand volcanoes, and other seismic artifacts roughly 500 years old, corresponding to a recorded earthquake in 1548. The Himalayas sit atop one of the most active tectonic boundaries on Earth, where the Indian plate grinds beneath the Eurasian plate at a rate that guarantees future ruptures. A 2001 study published in Science calculated that 70 percent of the Himalayas could experience an extremely powerful earthquake, based on the accumulated strain since 1950. In 2015, a magnitude 7.8 earthquake struck Nepal, far to the west. The eastern Himalayas, where the 1950 rupture occurred, continue to accumulate stress. Nearly 4,800 people died in 1950. The next great earthquake in this region is not a question of whether but when.