WhereIsAtlas · Natural disaster

2004 Indian Ocean Tsunami

The deadliest tsunami in recorded history

Concluded — An undersea earthquake off Sumatra triggered a tsunami that killed around 228,000 people across 14 countries.

On 26 December 2004, a magnitude 9.1-9.3 undersea earthquake struck off the west coast of Sumatra, Indonesia, displacing a huge volume of water and generating a tsunami that raced across the Indian Ocean.

Within hours, walls of water hit the coastlines of 14 countries - Indonesia, Sri Lanka, India, Thailand and Somalia among them. The earthquake's epicentre was near densely populated Banda Aceh, which was devastated. The global death toll is generally put at around 228,000, making it one of the deadliest natural disasters in recorded history.

The disaster spurred an enormous international relief effort and, importantly, the creation of the Indian Ocean Tsunami Warning System - a network intended to ensure that so many lives are never again lost to an unwarned wave.

Timeline

Dec 26, 2004 — The earthquake: A huge undersea earthquake ruptures off the west coast of Sumatra.
Dec 26, 2004 — The tsunami: Waves sweep across the Indian Ocean, hitting 14 countries within hours.
2004-05 — The recovery: An enormous global relief effort and reconstruction follow.
2005+ — The warning system: The Indian Ocean Tsunami Warning System is built to prevent a repeat.

Quick facts

Date: Dec 26, 2004
Magnitude: 9.1-9.3
Deaths: ≈ 228,000 (estimates vary)
Countries hit: 14
Epicentre: Off Sumatra, Indonesia

Sources

2004 Indian Ocean earthquake and tsunami - Wikipedia — Wikipedia (2026-02-10)
The 2004 Indian Ocean tsunami — USGS (2026-02-10)