Reliable early warning systems vital for tsunami preparedness

The 2004 Indian Ocean tsunami was one of the worst natural disasters in recorded history. More than 220,000 people across a dozen countries were killed. Before 2004, the Indian Ocean had no dedicated tsunami warning system, leaving the region largely unprepared for such disasters. Just one month after the disaster, world leaders gathered at a UN conference to establish the Indian Ocean Tsunami Warning System. It uses a network of sensors and buoys to detect changes in water pressure caused by seismic activity. Grace Shin explains.