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News Releases 2003
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NOAA’s DART system hit the bull’s-eye Nov. 17 when it detected a small tsunami generated by an earthquake near Adak, Alaska. DART is the Deep Ocean Assessment and Reporting of Tsunamis. The National Oceanic and Atmospheric Administration (NOAA) is an agency of the U.S. Department of Commerce.
“This was the first time since it went operational in October that we had a chance to put it through its paces and it worked as planned,” said Eddie N. Bernard, director of NOAA’s Pacific Marine Environmental Laboratory in Seattle, Wash., where the warning system was developed, designed and built. “This is the first time we were able to capture tsunami data in real-time in an operational mode.”
Bernard will talk about the DART system during a special session on tsunami research and mitigation at 8 a.m., Tuesday, Dec. 9 at the fall meeting of the American Geophysical Union in San Francisco, Calif.
As part of the U.S. National Tsunami Hazard Mitigation Program (NTHMP), the DART project is an ongoing effort to maintain and improve the capability for the early detection and real-time reporting of tsunamis in the open ocean.
A tsunami is a series of ocean waves generated by any rapid large-scale disturbance of the sea water. Most tsunamis are generated by earthquakes, but they may also be caused by volcanic eruptions, landslides, undersea slumps or meteor impacts.
While the buoys worked well during the research phase, Mother Nature on Nov. 17 offered up a 7.5 earthquake in the Aleutian Islands, the first such test of the system in operational mode. The data can be viewed by clicking on “46401 event” at: http://www.ndbc.noaa.gov/dart.shtml.
Bernard noted DART works as designed. The trigger from the earthquake waves can be seen around 0645 and the tsunami arrival around 0750.
The Nov. 17 event was similar in magnitude to an event from the same region in 1986, which triggered a tsunami warning that resulted in the evacuation of Hawaii coastal areas. The tsunami that ultimately struck the Hawaii coastline, however, was less than a foot in height and caused no damage. The average cost of lost business and productivity because of the evacuation was estimated by the State of Hawaii’s Department of Business, Economic Development and Tourism to be $40 million.
The State of Hawaii’s response to this most recent earthquake/tsunami cost about $68 million less (adjusted for inflation) because, for the first time, real-time data were available, and no evacuation was ordered.
In October, DART moved from research to operations and is now operated by the NOAA’s National Weather Service’s National Data Buoy Center.
There are now six DART systems along the Pacific coast of the United States and the equator. A DART system is being installed off of the coast of Chile, and Bernard says that other nations are interested in the technology.
The DART systems consist of an anchored seafloor bottom pressure recorder (BPR) and a companion moored surface buoy for real-time communications. An acoustic link transmits data from the bottom pressure recorder on the seafloor to the surface buoy. The data are then relayed via a GOES satellite link to ground stations, which demodulate the signals for immediate dissemination to NOAA's Tsunami Warning Centers, the National Data Buoy Center, and PMEL.
Bernard said DART is consistent with the other in situ earth observing technology and is essential to fulfilling NOAA's national responsibility for tsunami hazard mitigation and warnings.
About 18 years ago, the idea for DART was formed and steps were taken to prove that the sensors could measure a tsunami as a way for an early-warning device in the deep ocean. In 1997, the National Tsunami Hazard Mitigation Program provided funding for DART development. Following successful tests, the system made the move to operations in October.
Bernard said that the Nov. 17 information from the DART system was run against a tsunami model of the same situation. The model was off by less than one centimeter in water height. “What we will do now is use the real-time data in the forecast model and refine the model.”
NOAA is dedicated to protecting and preserving our nation’s living marine resources through scientific research, management, enforcement, and the conservation of marine mammals and other protected marine species and their habitat.
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