Tsunami Warning Centers
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Tsunami Warning Centers




A tsunami warning center is an entity established by a government agency to warn citizenry of the approach of any potentially life-threatening seismic sea wave, or tsunami. The effectiveness of a tsunami warning center is directly tied to the resources at its disposal, including personnel, equipment, monitoring and modeling capabilities; education, training and procedures in place to respond to an event; effectiveness of communications conduits, both internal (hierarchical and interagency) and external (government, military, civil defense, educational and mass media); and the willingness of individuals and communities likely to be impacted by a tsunami to devote their own time and resources to education and preparation for such an event.

The Pacific Tsunami Warning Center (PTWC) is responsible for providing tsunami warnings and tsunami alerts to most Pacific Rim nations. Alaska and the U.S. West Coast are served by the West Coast & Alaska Tsunami Warning Center. The Pacific Tsunami Warning Center serves as the operational center for the Tsunami Warning System of the Pacific (TWS). The PTWC collects and evaluates data provided by participating countries and issues appropriate bulletins to participants and to 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 2004 tsunami that devastated the coastlines of many Indian Ocean nations and resulted in over a quarter million lives lost or presumed lost dramatized the gross inadequacy of global tsunami warning procedures. In point of fact, no tsunami warning procedures existed for the Indian Ocean basin. Whether through simple government inaction, unwillingness to allocate funding for an event having a perceived low probability of occurrence within the foreseeable future, inability of governments to coordinate their efforts (Where was the United Nations with regard to the tsunami threat?), or merely ignorance of the problem, nothing had been done.

Further exascerbating the severity of the 2004 Indian Ocean tsunami was the inability of the Pacific Tsunami Warning Center (PTWC), whose personnel were aware of the potential (with the recording of the 9.1+ Richter magnitude Sumatra-Andaman earthquake), then the actuality (initial reports of the seismic sea wave), for a cataclysmic event, to alert Indian Ocean nations to the danger their citizens were facing. Debate rages over responsibility for this lack of action.

While many place blame squarely upon the PTWC for the lack of warning, I do not believe there was any orchestrated attempt at inaction, as some have claimed. Rather, I prefer to think of this as one more example of an emergency situation in which lack of foresight and the resultant failure to properly train and formulate a plan of action created a “deer in the headlights” response. While some actions were taken, what was achieved in comparison to the magnitude of the unfolding disaster was woefully inadequate.

Another factor that contributed appreciably to the high death toll, as is true of all natural disasters, was the inability of individuals in the danger zone to comprehend what was happening and take appropriate action due to a lack of education. This tended to be more true with regard to the tourists who had flocked to the numerous vacation spots dotting the Indian Ocean Rim. Many of the residents of the region, who might be considered by some Westerners to be less educated, had inherited stories of big waves from their grandparents and warned tourists to flee to higher ground. Like a cat drawn by curiosity toward a large spider, children and others unaware of the imminent danger moved directly into the path of the wave front as they sought to investigate a rapidly receding shoreline and the fish that had been stranded by its retreat.

An Indian Ocean Tsunami Warning System (IOTWS) is now undergoing active development and testing under the auspices of the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO). While it is tragic that this system is the result of a catastrophy unrivaled in recent history (other than wars), it will go a long way toward preventing a recurrence. Still to be addressed are other tsunami hazard zones such as the Atlantic Ocean and Mediterranean Sea.

References:
Authored by Kenneth L. Anderson.  Original article published 14 February 2007.


See our Tsunami (Tidal Wave) Hazard page for facts about tsunamis and tsunami articles and websites.

The following information about Tsunami Bulletins has been provided courtesy of the International Tsunami Information Centre (ITIC), which is operated by the National Weather Service in association with the Intergovernmental Oceanographic Commission (IOC) of the United Nations Educational, Scientific and Cultural Organization (UNESCO). This information is in the public domain and is not subject to copyright protection but, if you reference it, please acknowledge its source.


Tsunami Bulletins

Tsunami Warning / Watch / Advisory bulletins issued by the National Weather Service’s tsunami warning centers are alphanumeric products providing tsunami warning, watch and advisory information for potentially damaging tsunamis. The centers’ operational objectives are to:
  • locate and size major earthquakes in the Pacific basin;
  • determine their tsunamigenic potential;
  • predict tsunami wave arrival times and, when possible, run-up on the coast;
  • provide timely and effective tsunami information and warnings to the population of the Pacific to reduce the hazards of tsunamis, especially to human life.
Tsunami bulletins are prepared by each of two Tsunami Warning Centers. The West Coast & Alaska Tsunami Warning Center (WCATWC), located in Palmer, Alaska, issues tsunami bulletins to its Area of Responsibility (AOR) — Alaska, British Columbia, Washington, Oregon, and California. It also has the primary responsibility for the detection, location, and magnitude determination for potentially tsunamigenic earthquakes occurring in its AOR. The Pacific Tsunami Warning Center (PTWC), located at Ewa Beach, Oahu, Hawaii, has the responsibility for issuing tsunami bulletins to its AOR — Hawaii, all other U.S. interests in the Pacific, and most other countries within the Pacific and around its rim. It has the primary responsibility for the detection, location, and magnitude determination for potentially tsunamigenic earthquakes occurring anywhere in the Pacific Basin outside the WCATWC AOR.


Pacific-Wide Tsunami Warning

A Pacific-wide Tsunami Warning bulletin is issued by the PTWC after confirmation has been received that a tsunami has been generated in the Pacific that has caused damage, or has the potential to cause damage, at distances greater than 1,000 kilometers from the epicenter, thus posing a widespread threat to any populated coastal area within the Pacific Basin. Subsequent bulletins are issued at least hourly or as conditions warrant to reiterate the threat and to provide sea level gauge readings and other reports of tsunami wave activity. When significant wave activity has subsided, a warning cancellation is issued.


Regional Tsunami Warning

A Regional Tsunami Warning bulletin is a tsunami warning issued initially to coastal areas near the earthquake epicenter. It is usually based only on seismic information without tsunami confirmation, and is initially issued as a means of providing the earliest possible alert of a potentially destructive tsunami to the population near the epicentral area of a potentially tsunamigenic earthquake. Areas in a Regional Tsunami Warning are generally less than three hours from the estimated tsunami arrival time. A list of estimated arrival times for warning areas is provided in the bulletin. This condition implies that all coastal areas in the region should be prepared for imminent flooding. Subsequent bulletins are issued at least hourly or as conditions warrant to continue the warning, to expand or restrict the warning area, or to end the warning. A Regional Tsunami Watch and Advisory may also be issued in the same bulletin.


Urgent Local Tsunami Warning

An Urgent Local Tsunami Warning is a tsunami warning issued by the PTWC to Hawaii for tsunamis generated in Hawaiian coastal waters. It may be based only on seismic information without tsunami confirmation, or on a combination of seismic and sea level data, and is issued as a means of providing the earliest possible alert of a potentially destructive local tsunami. Areas in an Urgent Local Tsunami Warning may have only minutes or seconds before tsunami waves arrive, so urgent action is required to save lives. Subsequent bulletins are issued as conditions warrant to continue the warning, to expand or restrict the warning area, or to end the warning.


Final Warning Supplement

A Final Warning Supplement bulletin is issued following a damaging or potentially damaging tsunami within a center’s AOR that may pose a continuing threat. A Final Warning Supplement bulletin provides guidance to local officials on when they can consider the threat to have passed based on their local tsunami conditions. The cancellation or all clear decision must be made locally.


Warning Cancellation

A Warning Cancellation is issued as the final bulletin indicating when there is no longer the threat of a damaging tsunami to a center’s AOR. A Warning Cancellation is usually issued after an evaluation of sea level data confirms that a destructive tsunami will not impact the AOR. It may also be issued following a destructive tsunami when data indicate that the threat has largely subsided to non-destructive levels. In that case, it provides guidance to local officials regarding when they can consider the threat to have passed based on their local tsunami conditions. The all clear decision must be made locally.


Regional Tsunami Watch

A Regional Tsunami Watch is a tsunami watch issued in conjunction with a Regional Tsunami Warning to coastal areas near the earthquake epicenter, but outside the warning area. It is usually based only on seismic information without tsunami confirmation, and is issued as a means of providing the earliest possible alert of a potentially destructive tsunami. Areas in a Regional Tsunami Watch are generally less than six hours from the estimated tsunami arrival time, and a list of estimated arrival times for watch areas is provided in the bulletin. Subsequent bulletins are issued at least hourly or as conditions warrant to continue the warning and watch, to expand or restrict the warning and watch areas, to upgrade the watch to a warning, or to end the warning and watch. A Regional Tsunami Warning and advisory may also be issued in the same bulletin. The bulletin, usually based only on seismic information without tsunami confirmation, is issued as a means of alerting the population within one to three hours travel time beyond the tsunami warning area of an earthquake with the potential to have generated a tsunami that may affect that area. Subsequent bulletins are issued at least hourly or as conditions warrant to expand the watch area, upgrade it to a warning, or end the watch and warning. A Regional Tsunami Watch may be included in the text of the message that disseminates a Regional Tsunami Warning.


Tsunami Advisory Bulletin

A Tsunami Advisory bulletin is issued to areas not currently in either warning or watch status when a tsunami warning has been issued for another region of the Pacific. A Tsunami Advisory indicates that an area is either outside the current warning and watch regions or that the tsunami poses no danger to that area. The center(s) issuing the Tsunami Advisory will continue to monitor the event, issuing updates at least hourly. As conditions warrant, the Tsunami Advisory will either be continued, upgraded to a watch or warning, or ended.


Tsunami Information Bulletin

A Tsunami Information Bulletin (TIB) is issued for informational purposes for events that will not cause a destructive tsunami but were large enough in size to have been detected by the tsunami warning center’s seismic monitoring networks. Some of these earthquakes may have been large enough, however, to cause earthquake-related damage.


Follow links to the right to learn more about tsunami warning centers, how they function, and how tsunami warnings are generated. At the left margin, Related Links address topics of interest pertaining to geologic hazards and other security issues. View the Security & Consumer Protection SiteMap for a complete list of security and consumer protection topics.


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