Tsunamis kill thousands in South, Southeast Asia, some in east Africa

The world's most powerful earthquake in 40 years erupted underwater off the northwest coast of the Indonesian island of Sumatra on Sunday, 26 December 2004, sending walls of water barreling thousands of miles, killing more than 250,000 people in half a dozen countries across South and Southeast Asia as well as parts of east Africa, with thousands more missing or unreachable.

The earthquake, which measured 9.0 in magnitude, set off tsunamis that built up speeds of as much as 500 miles per hour, then battered the coasts of Sri Lanka, India, Thailand, Indonesia, the Maldives, Myanmar and Malaysia as 40-foot-high walls of water, devouring everything and everyone in their paths.

Huge waves swept some 7,000 kilometres as far as east Africa, crashing on to the shores of Kenya and Somalia, affecting the islands of Mauritius, Reunion and the Seychelles on the way, and leaving several people missing there.

On this page are links to news stories on the catastrophe as well as information and resources on tsunamis and natural disasters.

What is a tsunami?

Tsunami is a series of large waves of extremely long wavelength and period usually generated by a violent, impulsive undersea disturbance or activity near the coast or in the ocean. When a sudden displacement of a large volume of water occurs, or if the sea floor is suddenly raised or dropped by an earthquake, big tsunami waves can be formed by forces of gravity. The waves travel out of the area of origin and can be extremely dangerous and damaging when they reach the shore. The word tsunami (pronounced tsoo-nah'-mee) is composed of the Japanese words "tsu" (which means harbour) and "nami" (which means "wave"). Often the term, "seismic or tidal sea wave" is used to describe the same phenomenon, however the terms are misleading, because tsunami waves can be generated by other, non seismic disturbances such as volcanic eruptions or underwater landslides, and have physical characteristics different of tidal waves. The tsunami waves are completely unrelated to the astronomical tides - which are caused by the extraterrestrial, gravitational influences of the moon, sun, and the planets. Thus, the Japanese word "tsunami", meaning "harbour wave" is the correct, official and all-inclusive term. It has been internationally adopted because it covers all forms of impulsive wave generation.