System development and performance of the Deep-ocean Assessment and Reporting of Tsunamis (DART) system from 1997-2001

As part of the U.S. National Tsunami Hazard Mitigation Program, the Deep Ocean As- sessment and Reporting of Tsunamis (DART) Project is an ongoing effort by the Pacific Marine En- vironmental Laboratory (PMEL) to develop and implement a capability for the early detection and near real-time reporting of tsunamis in the open ocean. A DART system consists of a seafloor system, capable of detecting tsunamis as small as 1 cm, and a surface buoy for near real-time communica- tions. An acoustic link is used to transmit the data from the seafloor system to the surface buoy. The data are then relayed via a NOAA Geostationary Operational Environmental Satellite (GOES) satel- lite link to ground stations, which demodulate the signals for immediate dissemination to Tsunami Warning Centers and PMEL. A DART quality control page is made available to the public in near real time via the World Wide Web (http://tsunami.pmel.noaa.gov/dartqc/WaveWatcher). The general system design is fundamentally as envisioned in 1996, but many technical challenges had to be overcome during the development process. The surface buoys now incorporate redundant electronic packages to improve reliability and data return, and the seafloor system design now al- lows for 2-year deployments, to reduce the cost and effort of maintaining the oceanic network. The end-to-end DART system concept has been proven through numerous deployments, starting in July 1997 and continuing up to the present configuration of five operating DART stations. Performance measures such as cumulative data return, scheduled test transmissions, triggered transmissions, data dropouts, and system failures will be discussed. The results will show that during the past 5 years, the DART Project has successfully developed and tested a prototype system, which will lead directly to an operational Pacific DART Network.