Three days after the devastating M8.9 earthquake off the Pacific coast of Tohoku, a grim picture is emerging of the death and destruction wreaked by the tsunami and once again the world is reminded of the deadly force of the ocean. The scenes transmitted around the world have shocked us all, and the IOC sends it condolences to the people of Japan and pledges to continue its efforts to coordinate the implementation and improvement of tsunami warning systems globally.
The earthquake struck at 0546Z on 11 March with its epicenter some 130km east of the coast of Miyagi prefecture. The magnitude of the earthquake is now estimated by the Japan Meteorological Agency (JMA) as M9.0, making it the 4th largest recorded earthquake since 1900. There have been hundreds of aftershocks since the main earthquake, many greater than magnitude 6. The first tsunami wave arrived at the coastline nearest to the epicenter within about 15 minutes of the earthquake and in the hours that followed more waves arrived, in places 10m or even higher. Whole communities were washed away and much infrastructure was destroyed.
The tsunami propagated east into the Pacific Ocean and the first regional tsunami bulletins were issued by the North West Pacific Tsunami Advisory Centre (NWPTAC) operated by JMA and the Pacific Tsunami Warning Centre (PTWC) at 0555Z. Deep-ocean Assessment and Reporting of Tsunami (DART) buoys close to Japan were triggered and a wave of 1.08m amplitude (mean level to peak) was recorded at DART21418 at 0619Z, confirming that a large tsunami had been generated and was propagating eastward. The tsunami travel time and energy maps generated by the West Coast/Alaska Tsunami Warning Centre (WC/ATWC) shows the initial estimate of travel time across the ocean and the directionality of the wave energy.
PTWC initially issued wide spread tsunami warning bulletins for most Pacific Ocean countries and later reduced the number of countries on the basis of updated model results. In total, PTWC issued 27 bulletins during the event and NWPTAC issued 9 bulletins. The WC/ATWC issued its first bulletin at 0600Z and issued a total of 34 bulletins during the event. For a complete inventory of factual information about the event and the warning bulletins issued please see this link
Across the Pacific Ocean, countries were prepared well in advance for the arrival of the tsunami waves. Hawaii ordered statewide evacuations as waves of over 2m (trough to peak) passed the islands. The west coast of the USA experienced waves of over 4m (trough to peak) at Crescent City. Waves of over 4m (trough to peak) were also measured down the coast of Chile.
The role of the IOC in tsunami warning is to coordinate the regional tsunami warning systems through its Tsunami Unit. Since the Indian Ocean Tsunami of 2004, the UN has mandated the IOC to lead the coordination of Indian Ocean Tsunami Warning and Mitigation System (IOTWS), based on its more than 45 years of coordinating the Pacific Tsunami Warning and Mitigation System (PTWS). Similar systems in the Caribbean (CARIBE-EWS) and the North-Eastern Atlantic and Mediterranean (NEAMTWS) are also coordinated by the IOC. Each system is governed by an Intergovernmental Coordination Group (ICG) which reports directly to the IOC Assembly. The ICGs therefore operate at a high-level, allowing the Member States to collaborate for the collective benefit of all the countries in each ocean basin.
During this event, the PTWS operated well and according to expectations. The seismic detection systems were able to identify the location and magnitude of the earthquake within minutes allowing for timely regional warnings to be issued to the Pacific Ocean countries. The DART buoys and sea level monitoring stations worked well and the communications systems allowed for near real-time monitoring of the event. The Regional Tsunami Warning Centres issued timely bulletins and kept the National Tsunami Warning Centres of the PTWS well informed and updated on the progress of the tsunami.
However, it seems inappropriate to talk of any "success" in an event that has caused so much loss of life and extensive damage to infrastructure and livelihoods. Since 2004, there have been a number of deadly tsunamis: south Java in 2006; Solomons and Chile in 2007, Samoa/American Samoa/Tonga in 2009; Haiti, Chile and Mentawai (Indonesia) in 2010; and now the Tohoku tsunami in Japan. What each of these has in common is that they were local, rapid onset events, where tsunami waves arrived on the shore quickly, and in some places before warnings were issued or before people could evacuate to safety. The horrific scenes of destruction that we have witnessed through the media over the last three days should act as another reminder for countries with communities living close to potentially tsunamigenic zones to step up their efforts to develop awareness, preparedness and mitigation measures. Communities must learn to recognize the natural warning signs and act immediately to save their lives. Focused research is also required to continue updating our knowledge about subduction zones capable of generating great earthquakes and tsunamis. The IOC stands ready to support these activities in collaboration with partners and is more than ever committed to the goal of developing effective end-to-end tsunami warning systems at the regional, national and local level.