The first of a planned series of tsunami early warning buoys is being put down in the Indian Ocean. The buoy, provided by the US, (who already operate a similar system in the Pacific Ocean) is being placed between Thailand and Sri Lanka, two of the countries worst-hit by the 2004 tsunami which killed more than 200,000 people. The buoy can detect sudden increases in pressure deep under the sea and send signals to a buoy floating on the surface. Using satellite communication the buoy passes the gathered information to tsunami warning centres around the Indian Ocean to give coastal communities early warning of a tsunami.

The plan is to create a network of 24 buoys that will extend to Indonesia and Australia, along the deep and unstable fault-line that caused the 2004 earthquake.

The BBC’s South-East Asia correspondent said that system will only be effective if proper warning sirens are installed in coastal communities – so far only a few have them.