Pacific Tsunami Warning


The US NOAA Pacific Tsunami Warning Center (PTWC) serves as the operational center for the Pacific TWS and the PTWS.  Sub-regional centres in Japan (JMA Northwest Pacific Tsunami Adviosry Center, NWPTAC) and Alaska (US NOAA National Tsunami Warning Center, US NTWC), work with PTWC to provide international warnings and advisories for the Pacific and its marginal seas.  The international Tsunami Warning Centres (TWC) collect and evaluate data provided by participating countries, and issue appropriate bulletins to both participants and other nations, states or dependencies within or bordering the Pacific Ocean basin regarding the occurrence of a major earthquake and possible or confirmed tsunami generation. The messages are advisories to national authorities, as each country is individually responsible for issuing warnings and public safety information to its own population.  

The three international centres work closely together to ensure the timely and consistent delivering of tsunami advisories.  The first advisories that are issued are usually based only on seismic information.  As sea level data are received on coastal or deep-ocean gauges, the generation of a tsunami and its severity can be confirmed, and appropriate advisories issued. 
The analyses and evaluations provided by the Centres, while performed using slightly different methods and data networks, generally report identical or closely similar results.  It is recommended that when discrepancies do occur, national agencies receiving the information assume the conservative or worst case scenario in making their decisions regarding life safety.

The Operational Users Guide for the Pacific Tsunami Warning and Mitigation System (PTWS) gives a summary of the Pacific’s international alert services.  The Guide is intended for use by the National Tsunami Warning Focal Points as customers receiving the advisories from the international centres.   Topics include operational tsunami warning centre procedures, seismographic and sea level networks used by the warning centres, criteria for the reporting and issuing of tsunami information messages, recipients of the information, and the methods by which the messages are sent.  Annexes provide additional background on tsunamis, earthquake source characterizations, guidance on message interpretation and emergency responses, sea level measurements, travel time calculation and wave forecasting.

Pacific Tsunami
Warning - Summary

PDF icon  408 KB

PTWC Pacific Tsunami Bulletins

PDF icon  135 KB

JMA Pacific Tsunami Bulletins (NWPTAC)

PDF icon  208 KB

US NTWC Pacific Statements

PDF icon  176 KB

PTWS Message Issuance General Summary

PDF icon  51.6KB

Global Tsunami
Warning and Advisory
Message Products

PDF icon  81.9 KB




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DVD copies for PC and Macintosh computers are available free of charge from the ITIC, Hawaii (

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