National Tsunami Warning Center

The National Tsunami Warning Center (NTWC) is one of two tsunami warning centers in the United States, covering all coastal regions of the United States and Canada, except Hawaii, Guam, the Northern Mariana Islands, Puerto Rico and the U.S. Virgin Islands.

The NTWC, operated by the National Oceanic and Atmospheric Administration (NOAA), detects and analyzes earthquakes worldwide, issuing warnings to local officials in the hazard zones about the advisability of evacuating low-lying coastal areas and moving ships to deep water.

The City of Palmer, in the Matanuska Valley 42 miles northeast of Anchorage, was selected as the site for the primary observatory due to its proximity to bedrock for instrumentation and to communications facilities.

On 1 October 2013, the name was changed to the National Tsunami Warning Center (NTWC) to reflect this expanded geographical zone of responsibility.

To accomplish its mission of providing accurate and timely tsunami bulletins to its area-of-responsibility (AOR) – which includes Canadian coastal regions, Puerto Rico and the Virgin Islands, and the ocean coasts of all U.S. States except Hawaii – the NTWC detects, locates, sizes, and analyzes earthquakes worldwide.

Earthquakes large enough to be felt near the coast, but below the tsunami warning/watch/advisory threshold size, prompt informational statements to the same recipients as warnings to help prevent needless evacuations.

[3] Beginning in 2005, as a result of the tsunami caused by the 2004 Indian Ocean earthquake, plans were announced to add 32 more DART buoys to be operational by mid-2007.

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 via acoustic modem.