Dec. 8, 2003 — 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. “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 the NOAA 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.” (Click NOAA image for larger view of buoy at the D-157 site just after being set in the water and riding high with no mooring load. Typical October seas in the North Pacific. Please credit “NOAA.”)

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, 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. (Click NOAA image for larger view of crew aboard the NOAA ship RONALD H. BROWN taken in October 1999 during deployment cruise of DART buoy in the North Pacific. Please credit “NOAA.”)

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.”

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 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 the NOAA Tsunami Warning Centers, the National Data Buoy Center, and Pacific Marine Environmental Lab. (Click NOAA image for larger view of bottom pressure reorder or BPR ready for deployment at D-165 site. The silver titanium case holds all electronics for the pressure gauge and acoustic modem, the white tubes hold batteries, the acoustic modem transducer is on the left housed in a yellow foam baffle and the acoustic release is mounted in the middle with attachment to the steel anchor below. Please credit “NOAA.”)

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 enhancing economic security and national safety through the prediction and research of weather and climate-related events and providing environmental stewardship of the nation’s coastal and marine resources. NOAA is part of the U.S. Department of Commerce.

Relevant Web Sites
DART — Deep Ocean Assessment and Reporting of Tsunamis

U.S. National Tsunami Hazard Mitigation Program

NOAA Pacific Marine Environmental Laboratory

DART Animation

Media Contact:
Jana Goldman, NOAA Research, (301) 713-2483