Tsunami of 2004, Indian Ocean

A major tsunami took place on December 26, 2004, which was the deadliest tsunami in recent history. On that fateful day, the tsunami left more than 225,000 people dead or missing, with many millions made homeless in a total of 11 countries. Indonesia, Sri Lanka, India, and Thailand were the hardest hit.

Figure 1 A regional map of those countries most affected by the tsunami. This map also illustrates the approximate land coverage under 20 m in elevation as a zone of potential tsunami damage.

Source: Courtesy of UNOSAT, the UN Institute for Training and Research (UNITAR) Operational Satellite Applications Programme, implemented in cooperation with the European Organization for Nuclear Research (CERN). Map based on data provided by International Charter Space and Major Disasters.

The tsunami was caused by an offshore (undersea) earthquake of magnitude 9.2 that was triggered along an area of plate collision where the India Plate, an oceanic plate, is being subducted beneath the Burma-Sunda plate across a subduction zone in the area of the Sunda Trench. The epicenter of the 9.0-magnitude quake was under the Indian Ocean off the western coast of Sumatra, Indonesia. The earthquake was associated with the rupture of the seafloor along a length of 1,000 km (kilometers; 620 mi. [miles]). Along this zone, the land surface was displaced both laterally and vertically by several meters. This event led to the sudden displacement of the overlying ocean water and the production of the tsunami.

Along the coast of Northern Sumatra, tsunami waves up to 30 m (meters; 100 ft. [feet]) in height destroyed everything in their path. The tsunami traveled across the Indian Ocean, causing devastation along coastlines as far as away as Somalia, Kenya, and the Maldives. Some of the most destructive flooding took place along the coasts of Thailand, Sri Lanka, and India, where many thousands of people lost their lives and many more lost their livelihoods.