Tsunami Warning Centers

The IOC is coordinating the implementation of the global tsunami warning system, building upon its exper iences in the Pacific to establish warning centers for the Indian Ocean, Caribbean Sea, and the Mediterranean Sea. The Pacific Tsunami Warning Center (PTWC) serves as the international warning center for the Pacific. This international warning effort became a formal arrangement in 1965 when PTWC assumed responsibility as the operational center for the Tsunami Warning System in the Pacific (TWSP). The ICG/ITSU, presently comprised of 26 international Member States, oversees warning system operations and facilitates coordination and cooperation in all international tsunami mitigation activities. Until a regional warning center is permanently established in the Indian Ocean, the PTWC and Japan Meteorological Agency (JMA) will cooperatively provide interim warning services.

The initial objective of PTWC is to detect, locate and determine the seismic parameters of potentially tsunamigenic earthquakes occurring in the Pacific Basin or its immediate margins. To accomplish this, it continuously receives seismographic data from more than 150 stations around the Pacific through cooperative data exchanges with the U.S. Geological Survey, Incorporated Research Institutions for Seismology, International Deployment of Accelerometers, GEOSCOPE, the U.S. National Tsunami Warning Center (US NTWC), and other national and international agencies running seismic networks.

If an earthquake has the potential to generate a destructive tsunami based on its location, depth, and magnitude, a tsunami warning is issued to warn of an imminent tsunami hazard. Initial warnings apply only to areas the tsunami could reach within a few hours and bulletins include the predicted tsunami arrival times at selected coastal communities within those areas. Communities located outside those areas are put into either a tsunami watch or advisory status.

Warning center scientists then monitor incoming sea level  data to determine whether a tsunami has occurred. If a significant tsunami with long-range destructive potential is detected, the tsunami warning is extended to the entire Pacific Basin. PTWC receives sea level data from more than 100 stations through cooperative data exchanges with the U.S. National Ocean Service, US NTWC, the University of Hawaii Sea Level Center, Chile, Australia, Japan, Russia, French Polynesia, and other international sources. Tsunami warnings, watches, and information bulletins are disseminated to appropriate emergency officials and the general public by a variety of communication methods.

In addition, individual countries may operate National or Regional Warning Centers to provide more rapid or detailed warning information regarding regional or local tsunami threats. The JMA provides tsunami warnings to Japan, and additionally through its Northwest Pacific Tsunami Information Center, provides earthquake and tsunami wave forecasts to Russia, Korea, China, the Philippines, Papua New Guinea and island nations in the North Pacific for events in the Japan or East Sea, and in the northwest Pacific. The Centre Polynesien de Prevention des Tsunamis provides regional warnings in French Polynesia. Australia, Chile, New Zealand, Peru, and Russia operate national warning systems. 

In the United States, US NTWC provides tsunami warnings to the U.S. West Coast and Canada, and PTWC provides tsunami warnings to Hawaii and to all other U.S. interests in the Pacific. PTWC is the interim warning center to countries in the Coastal Hazards Warning System for the Caribbean and Adjacent Regions (CARIBE). From 2005-2007, PTWC was the interim warning center to U.S. Interests (Puerto Rico, Virgin Islands) in the Caribbean Sea. The US NTWC now provides this service to U.S. interets in the Caribbean. Through the open and timely sharing of data, Warning Centers can provide backup and supplemental analyses of events should a Center become disabled. The Centers can also serve as focal points for regional tsunami awareness, education, and other mitigation activities.