On December 26 2004, an undersea earthquake occurred  with an epicenter off the west coast of Sumatra, Indonesia. The earthquake triggered a series of devastating tsunamis that spread throughout the Indian Ocean, killing large numbers of people and inundating coastal communities across South and Southeast Asia, including parts of Indonesia, Sri Lanka, India, and Thailand. 

The tsunamis claimed the lives of approximately 230,000 people. The death toll in Indonesia alone is over 160,000.  The catastrophe is one of the deadliest disasters in modern history.

The magnitude of the earthquake was originally recorded as 9.0 on the Richter scale, but has been upgraded to between 9.1 and 9.3. At this magnitude, it is the second largest earthquake ever recorded on a seismograph. This earthquake was also reported to be the longest duration of faulting ever observed, lasting between 500 and 600 seconds, and it was large enough that it caused the entire planet to vibrate at least half an inch, or over a centimetre. It also triggered earthquakes in other locations as far away as Alaska.

The earthquake originated in the Indian Ocean just north of Simeulue island, off the western coast of northern Sumatra. The resulting tsunami devastated the shores of Indonesia, Sri Lanka, India, Thailand and other countries with waves up to 30 meters.  It caused serious damage and deaths as far as the east coast of Africa, with the furthest recorded death due to the tsunami occurring at Port Elizabeth in South Africa, 8,000 km away from the epicentre.

The plight of the many affected people and countries prompted a widespread humanitarian response. 

(See more photos of the effects of the tsunami in Aceh)