Indian Ocean Tsunami Warning System performed well, detailed assessment underway
The Indian Ocean Tsunami Warning System was activated 11 April 2012 following a strong earthquake off the west coast of Sumatra in Indonesia that triggered waves of an amplitude of up to about one metre. Overall, the system performed well during this first ocean-wide test for the Regional Tsunami Service Providers. UNESCO’s Intergovernmental Oceanographic Commission will conduct a full survey and prepare an assessment report to identify potential improvements of the system.
UNESCO-IOC took the lead in coordinating activities and immediate action to establish a Tsunami Warning System (TWS) in the Indian Ocean following the undersea earthquake on 26 December 2004 and the subsequent strongest tsunami in living memory
Such warning systems are comprised of three components:
- Hazard assessment, detection and forecasting,
- Threat evaluation and dissemination, and
- Community preparedness and response, where education is key.
The system involves actors at the regional, national and local levels to gather, analyse and disseminate information. Minutes after the earthquake, Indian Ocean Regional Tsunami Service Providers of Australia, India and Indonesia issued bulletins with detailed information and threat evaluations. The Indonesian Tsunami Early Warning System issued its first national bulletin 5 minutes after the event, and the RTSP India issued its first bulletin 8 minutes after the event, well within the system’s performance standard of 10 minutes.
A preliminary assessment indicates that National Tsunami Warning Centres received timely bulletins and reacted accordingly. Preventive evacuations were ordered in some areas. Given the magnitude of the earthquakes, the immediate concern was that a large tsunami would be generated. Subsequent bulletins were issued as more information became available and the threat was revaluated.
The sea level monitoring network comprising deep sea tsunami monitoring buoys and coastal sea level gauges operated well and were crucial in confirming that a large tsunami wave had not been generated. RTSP wave forecasts and threat assessments were subsequently downgraded.
‘The education of the public is absolutely critical’, stressed Wendy Watson Wright, UNESCO-IOC Executive Secretary, when interviewed. She believes that the self-evacuations that took place in some areas are an indication that community preparedness and response efforts are paying off.
The latest full-scale test of the Indian Ocean Tsunami Warning and Mitigation System had taken place on 12 October 2011. Each activation of the system, whether real or simulated, is an opportunity to identify weaknesses and revise procedures. In this case, some problems did emerge; a full analysis will be conducted and further improvements will be made.
- Regional Tsunami Service Providers:
- Intergovernmental Coordination Group for the Indian Ocean Tsunami Warning and Mitigation System
- International Tsunami Information Center
- CNN interview
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