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Pacific Tsunami Warning Center

Pacific Tsunami Warning Center

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The Pacific Tsunami Warning Center (PTWC) is one of two tsunami
Tsunami
A tsunami is a series of water waves caused by the displacement of a large volume of a body of water, typically an ocean or a large lake...

 warning centers that are operated by NOAA in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...

. Headquartered in Ewa Beach, Hawaii, the PTWC is part of an international tsunami warning system
Tsunami warning system
A Tsunami warning system is used to detect tsunamis in advance and issue warnings to prevent loss of life and damage. It consists of two equally important components: a network of sensors to detect tsunamis and a communications infrastructure to issue timely alarms to permit evacuation of coastal...

 (TWS) program and serves as the operational center for TWS of the Pacific issuing bulletins and warnings to participating members and other nations in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

 area of responsibility . It is also the regional (local) warning center for the State of Hawaii
Hawaii
Hawaii is the newest of the 50 U.S. states , and is the only U.S. state made up entirely of islands. It is the northernmost island group in Polynesia, occupying most of an archipelago in the central Pacific Ocean, southwest of the continental United States, southeast of Japan, and northeast of...

. The other tsunami warning center is the West Coast and Alaska Tsunami Warning Center
West Coast and Alaska Tsunami Warning Center
The West Coast and Alaska Tsunami Warning Center is one of two tsunami warning centers that are operated by NOAA in the United States. Headquartered in Palmer, Alaska, the WCATWC is part of an international tsunami warning system program and serves as the operational center for TWS of all coastal...

 (WCATWC) in Palmer, Alaska
Palmer, Alaska
Palmer is the borough seat of the Matanuska-Susitna Borough in the state of Alaska, USA. It is part of the Anchorage Metropolitan Statistical Area. As of the 2010 census, the population of the city is 5,937....

, serving all coastal regions of Canada and the United States except Hawaii.

The PTWC was established in 1949, following the 1946 Aleutian Island earthquake
Aleutian Island earthquake
The 1946 Aleutian Islands earthquake was an earthquake near the Aleutian Islands on April 1, 1946. It was followed by a Pacific-wide tsunami. The earthquake was a magnitude 7.8, with its epicenter at 52.8°N, 163.5°W, and focal depth of 25 km. It resulted in 165 casualties and over $26...

 and a tsunami that resulted in 165 casualties in Hawaii and Alaska
Alaska
Alaska is the largest state in the United States by area. It is situated in the northwest extremity of the North American continent, with Canada to the east, the Arctic Ocean to the north, and the Pacific Ocean to the west and south, with Russia further west across the Bering Strait...

. After the 2004 Indian Ocean earthquake and tsunami, PTWC has extended its warning guidance to include the Indian Ocean, Caribbean and adjacent regions until regional capability is in place for these areas. These regional systems will form a global tsunami warning system once they are in operation.

The PTWC uses seismic data as its starting point, but then takes into account oceanographic data when calculating possible threats. Tide
Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the moon and the sun and the rotation of the Earth....

 gauges in the area of the earthquake are checked to establish if a tsunami has formed. The center then forecasts the future of the tsunami, issuing warnings to at-risk areas all around the Pacific basin if needed. There are never false alarms—if the PTWC issues a tsunami warning for a particular area, the tsunami is already on its way and will hit. As it takes more time for tsunamis to travel trans-oceanic
Teletsunami
A teletsunami is a tsunami that originates from a distant source, which is more than 1,000 km away from the area of interest . A teletsunami can travel across an entire ocean...

 distances, the PTWC can afford to take the time to make sure of its forecasts.

Bulletins


Depending on the seismic data, PTWC will issue the following types of bulletins:
Tsunami Information Bulletin
At this time, though a threat exists, there is no evidence that a tsunami is making its way across the Pacific.

Tsunami Watch
PTWC has determined the earthquake may very likely have created a tsunami and is advising parties to be alert as PTWC awaits tide data to support tsunami generation.

Tsunami Warning
PTWC finds conditions serious enough to issue immediate concern to parts of the Pacific. The message will include approximate arrival times for various parts of the Pacific.

Deep-ocean tsunami detection


In 1995, NOAA began developing the Deep-ocean Assessment and Reporting of Tsunamis
Deep-ocean Assessment and Reporting of Tsunamis
The Deep-ocean Assessment and Reporting of Tsunamis system is a component of an enhanced tsunami warning system.- Stations :...

 (DART) system. By 2001, an array of six stations had been deployed in the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

.

Beginning in 2005, as a result of the tsunami caused by the 2004 Indian Ocean earthquake
2004 Indian Ocean earthquake
The 2004 Indian Ocean earthquake was an undersea megathrust earthquake that occurred at 00:58:53 UTC on Sunday, December 26, 2004, with an epicentre off the west coast of Sumatra, Indonesia. The quake itself is known by the scientific community as the Sumatra-Andaman earthquake...

, plans were announced to add 32 more DART buoys to be operational by mid-2007.

These stations give detailed information about tsunamis while they are still far off shore. Each station consists of a sea-bed bottom pressure recorder (at a depth of 1000–6000 m) which detects the passage of a tsunami and transmits the data to a surface buoy
Buoy
A buoy is a floating device that can have many different purposes. It can be anchored or allowed to drift. The word, of Old French or Middle Dutch origin, is now most commonly in UK English, although some orthoepists have traditionally prescribed the pronunciation...

 via acoustic modem. The surface buoy then radios the information to the PTWC via the GOES
Goes
Goes is a municipality and a city in the southwestern Netherlands in Zuid-Beveland, in the province Zeeland. The city of Goes has approximately 27,000 residents.-History of Goes:...

 satellite
Satellite
In the context of spaceflight, a satellite is an object which has been placed into orbit by human endeavour. Such objects are sometimes called artificial satellites to distinguish them from natural satellites such as the Moon....

 system. The bottom pressure recorder lasts for two years while the surface buoy is replaced every year. The system has considerably improved the forecasting and warning of tsunamis in the Pacific Ocean.

Final transmission


Local populations in the United States of America receive tsunami information through radio and television receivers connected to the Emergency Alert System
Emergency Alert System
The Emergency Alert System is a national warning system in the United States put into place on January 1, 1997, when it superseded the Emergency Broadcast System , which itself had superseded the CONELRAD System...

, and in some places (such as Hawaii) civil defense siren
Civil defense siren
A civil defense siren is a mechanical or electronic device for generating sound to...

s and roving loudspeaker broadcasts from police vehicles. The public can subscribe to the RSS feed or email alerts from the PTWC web site, and the UNESCO site. Email and text messages are also available from the USGS Earthquake Notification Service which includes tsunami alerts.

External links