It’s been nearly three years since the magnitude 9.0 earthquake off the coast of Sumatra Island caused a massive tsunami across Indian Ocean coastlines. An estimated 300,000 people perished in eight countries, focusing world attention on the reality and destruction of tsunamis.
After the December 2004 tragedy, NOAA led the U.S. effort to build a more comprehensive tsunami warning system. The agency developed tsunami models for at-risk communities, staffed its warning centers around the clock, deployed additional Deep-ocean Assessment and Report of Tsunami (DART) buoy stations, installed sea level gauges, and expanded community education to help ensure a TsunamiReady America.
The Deep-ocean Assessment and Reporting of Tsunamis network has been expanded from six to 35 DART buoy stations, including the Atlantic. Developed by NOAA's Pacific Marine Environmental Laboratory and operated by NOAA's National Data Buoy Center, the stations provide real-time tsunami detection as the waves travel across the open ocean. The original six were all located in the Pacific Ocean. In April 2006, NOAA launched the first DART buoys in the Atlantic Ocean. The current network consists of 35 DART stations (28 in the Pacific and seven in the Atlantic/Caribbean).
All newly installed stations are a more robust DART II with advanced two-way satellite communication. NOAA expects the network to total 39 DART II buoy stations by the end of March 2008 (32 in the Pacific and seven in the Atlantic Basin).
A network of 49 sea-level stations is complete. NOAA’s Ocean Service upgraded 33 and installed 16 new stations. These automated stations record water level in one-minute intervals, then transmit that data via satellite to the tsunami warning centers. These data become more critical as a tsunami nears the shore.
NOAA’s Satellite and Information Service improved the quality and accuracy of the long-term archive of tsunami events. This global database includes information on nearly 2,000 tsunamis from 2000 B.C. to present and is used to identify regions at risk, validate the models, help position detection sensors, and prepare for future events. NOAA has quality assured/quality controlled data for 75 percent of the tsunamis that have impacted U.S. coasts and 50 percent of the most deadly global tsunamis. This work entails identifying and documenting the source of past tsunamis; date, time and magnitude of earthquakes; maximum water heights; deaths; and damage.
NOAA Recognizes the Nation’s 50th TsunamiReady Community. On December 20, 2007, NOAA recognized the city of Samoa on California’s northern coast as the nation’s 50th TsunamiReady community. Other TsunamiReady recognitions of note include:
December 24, 2004, Sumatra tsunami in Sri Lanka.
High resolution (Credit: Chris Chapman, Schlumberger Cambridge Research, Cambridge, U.K.)
New tsunami impact forecast models have been developed for 26 major U.S. coastal communities at high risk for tsunamis. The models are used to create inundation and evacuation maps for emergency managers and to help NOAA’s warning centers forecast tsunamis. Models for additional areas are underway, with the goal of expanding the geographical coverage of NOAA’s Forecast Modeling System to cover a total of 75 U.S. coastal areas and continue improvements to existing forecast models.
NOAA’s two tsunami warning centers are staffed 24 hours a day, seven days. The Pacific Tsunami Warning Center, in Ewa Beach, Hawaii, and the West Coast/Alaska Tsunami Warning Center, in Palmer, Alaska, hired 15 employees to staff the centers day and night.
The centers are responsible for issuing tsunami advisories, watches, warnings and information messages to emergency management officials and the public. Warnings are broadcast through NOAA Weather Radio-All Hazards, NOAA Weather Wire, the Emergency Alert System, and the Emergency Managers Weather Information Network.
Information on tsunami threats are provided beyond the Pacific Ocean. With an enhanced communications network, NOAA’s warning centers can now alert the U.S. Atlantic Coast, Gulf of Mexico, Puerto Rico, the U.S. Virgin Islands, and Eastern Canada.
The West Coast/Alaska Tsunami Warning Center provides warnings for the U.S. Atlantic, Gulf of Mexico, Alaska, U.S. West Coast, Puerto Rico, the Virgin Islands, as well as the British Columbia and Atlantic coasts in Canada. The Pacific Tsunami Warning Center provides warnings all to other U.S. interests in the Pacific, including Hawaii. It also provides alerts for teletsunamis (tsunamis originating more than 1,000 km from the affected area) to most countries in the Pacific Basin.
In addition, the Pacific Tsunami Warning Center, in partnership with the Japan Meteorological Agency, is providing tsunami advisory and watch alerts to 20 Indian Ocean countries on an interim basis until regional warning centers can be established.
An effective tsunami warning system includes hazard detection, risk assessment, warning dissemination, and a public that understands what to do when a warning is sounded. NOAA has built a comprehensive tsunami warning system that includes all of these elements. The result is a nation better equipped to detect tsunamis and alert communities of the impending danger.