The third-largest earthquake ever recorded ruptured the seafloor off Sumatra, unleashing waves up to 30 meters high that struck coastlines from Indonesia to Somalia within hours. Entire villages in Aceh vanished; resort beaches in Thailand and Sri Lanka were scoured clean. The disaster exposed the absence of any Indian Ocean tsunami warning system and prompted a global overhaul of early-detection networks.
At 7:58 a.m. local time, the seabed off the coast of Sumatra lurched violently, releasing energy equivalent to thousands of atomic bombs. The rupture, nearly 1,600 kilometers long, generated a series of tsunamis that raced across the Indian Ocean at jetliner speed, giving coastal residents almost no warning before walls of water arrived.
Aceh province in Indonesia bore the worst of it, with entire towns swept away and roughly 170,000 people killed there alone. The waves crossed the ocean to strike Sri Lanka, India, and Thailand within two to seven hours, and reached as far as Somalia on the African coast, eight hours and 5,000 kilometers away. Tourists filming the water's strange retreat from beaches, unaware it signaled a coming wave, later provided some of the disaster's most haunting footage.
The catastrophe, which killed an estimated 230,000 people, became one of the deadliest natural disasters in recorded history. It also spurred the creation of the Indian Ocean Tsunami Warning System, launched in 2006, a direct response to the lack of any mechanism that might have saved tens of thousands of lives.