Indian Ocean tsunami 10 years on

On December 26, 2004, a devastating tsunami hit Southeast Asia leaving hundreds of thousands dead in countries bordering the Indian Ocean. Ten years later, we take a look back at the events surrounding the disaster and the system designed to warn people of the next incident.

Indian Ocean tsunami
10 years on

On December 26, 2004, a devastating tsunami hit Southeast Asia leaving hundreds of thousands dead in countries bordering the Indian Ocean. Ten years later, we take a look back at the events surrounding the disaster and the system designed to warn people of the next incident.

Updated: 24 December 2014

The wave

The earthquake

The sudden rupture of a huge fault beneath the Indian Ocean unleashed the devastating tsunami. This record-setting rupture was around 1,300km in length. Stretching from the epicentre up to the Andaman Islands and lasting almost 10 minutes, this earthquake was one of the largest in the last century.

Devastation

The tsunami resulted in the loss of at least 226,000 lives and the displacement of over 1.8 million people around the Indian Ocean.

Warning system

The last 10 years have seen the development of a sophisticated early warning system, costing over $400 million across 28 countries. Comprising 101 sea level gauges, 148 seismometers and nine buoys, the Indian Ocean Tsunami Warning System (IOTSW) can send alerts to countries' tsunami warning centres within 10 minutes of a quake.

Tsunameters

A device on the sea floor measures water pressure, calculating the height of the water column above.

Sending the warning

Communicating warnings to at-risk coastal communities, and making sure people get to safety in time remains the main concern. In some of the countries worst affected in 2004 - Thailand, Indonesia and India - much progress has been made, officials claim. But some serious concerns remain about this final, crucial stage.

Historical wave heights

Coastal runup waves generated by the 2004 tsunami were the highest recorded, purely by an earthquake, in centuries. The chart below looks at all recorded tsunami runup heights since a 100m wave hit Ambon Island, Indonesia in 1674.

Year

Sources: NOAA Pacific Marine Environmental Laboratory; NOAA Centre for Tsunami Research; Harvard Seismology Group, Miaki Ishii; AlertNet; UN; Disasterwatch; BNPB - Indonesia National Disaster Management-Coordination Board; Tsunami Evaluation Coalition; Ministry of Nation Building (Sri Lanka); Intergovernmental Oceanographic Commission, Tsunami Programme

East Africa includes Kenya, Seychelles, Somalia, Tanzania and Madagascar. Chart does not include Malaysia, Bngladesh and Myanmar, also affected.

Graphics by Simon Scarr, Jane Pong, Wen Foo, Gustavo Cabrera