Under the auspices of the Intergovernmental Oceanographic Commission (IOC), the Intergovernmental Coordination Group for the Pacific Tsunami Warning and Mitigation System met for the first time in 1968. This Pacific Tsunami Warning System (PTWS) was created by 26 member states and covers the Pacific Basin. Its activities are carried out by the Pacific Tsunami Warning Center (PTWC) in Hawaii. PTWC is operated by the National Weather Service (NWS) of the National Oceanic and Atmospheric Administration (NOAA). NWS also maintains the Alaska Tsunami Warning Center (ATWC) that covers Alaska, British Columbia, Washington, Oregon and California. PTWS monitors seismic stations of PTWC, but also of USGS and ATWC, to detect potentially tsunamigenic earthquakes. PTWS releases information bulletins or tsunami warnings that are extended to the Pacific basin. These products contain information about estimated tsunami arrival times, areas potentially most affected, possible tsunami impact as well as the earthquake magnitude, time, location and depth.

Main users are thus the 26 PTWS member states and other countries in the Pacific as well as the general public.

References:
PTWC Website (http://ptwc.weather.gov/, accessed on February 08, 2012)
V. Grasso and A. Singh, UNEP (Dec 2011, forthcoming): Early Warning Systems: State-of-Art Analysis and Future Directions.