'Everybody did exactly what they should have and the system worked very well.' That was the reaction to the response by Patricio Bernal, executive secretary of Unesco's Intergovernmental Oceanographic Commission. The UN's heritage body took the lead in developing an early-warning system after the 2004 tsunami, and it began operating 18 months later. A total of 25 seismographic stations, three deep-ocean sensors, and a series of sea-level gauges instantly pick up signs of an earthquake. The information is relayed in real time to the Japanese Meteorological Agency and the Pacific Tsunami Warning Centre in Hawaii. They relay their analyses within minutes to focal points in the system's member countries, which then transmit the data to the national and local authorities responsible for emergency-response action. Unesco spokeswoman Sue Williams said many of the technological glitches experienced early on had been ironed out, making for a process that 'happens very, very quickly - literally within minutes of an earthquake'. She acknowledged, though, that the system was still not perfect. 'The experts are continuing to improve it,' Ms Williams said from her Paris office. 'Education to teach local populations how to react, especially those living in coastal zones close to earthquake-prone areas, remains important. These communities may not have the time to wait for an official alert and need to know what to do as soon as they feel the earth start to shake.'