U.S. deep-sea tsunameter network fully operational

Abstract

In March 2008, the National Oceanic and Atmospheric Administration's (NOAA) National Data Buoy Center (NDBC) completed the deployment of the last of the 39-station network of deep-sea tsunameters. This effort was an integral part of the National Tsunami Hazard Mitigation Program. The Tsunami Program is part of a cooperative effort to save lives and protect property through hazard assessment, warning guidance, mitigation, research capabilities, and international coordination. NOAA's National Weather Service (NWS) is responsible for the overall execution of the Tsunami Program. This includes operation of the U.S. Tsunami Warning Centers (TWC) as well as leadership of the National Tsunami Hazard Mitigation Program. It also includes the acquisition, operations and maintenance of observation systems required in support of tsunami warning, such as NOAA's Deep-ocean Assessment and Reporting of Tsunamis (DARTreg), local seismic networks, coastal, and coastal flooding detectors. NWS also supports observations and data management through the National Data Buoy Center (NDBC). As part of NOAA's effort to strengthen tsunami warning capabilities, NDBC expanded the network from the original six stations to 39 stations and upgraded all stations from first-generation DARTreg I technology to second-generation DARTreg II technology. Consisting of bottom pressure recorder and a surface buoy, the tsunameters deliver sea-level data from the sea bottom to tsunami warning centers in less than three minutes. A significant capability of DART II is the two-way communications between the bottom pressure recorder and the Tsunami Warning Centers/NDBC using the Iridium Satellite LLC's commercial satellite communications system. The two-way communications allow the Tsunami Warning Centers to set stations in event mode in anticipation of possible tsunamis or retrieve the high-resolution (15-s intervals) data in one-hour blocks for detailed analysis. DART II systems transmit standard mode data, containing 24 estimated sea-level height observations at 15-minute intervals, once very six hours. The two-way communications allow for real-time troubleshooting and diagnostics of the systems. NDBC receives the data from the DART II systems, formats the data into messages and then delivers them to the National Weather Service Telecommunications Gateway (NWSTG) that then distributes the data in real-time to the Tsunami Warning Centers via NWS communications and nationally and internationally via the Global Telecommunications Systems. NDBC positioned the tsunameters between Hawaii and every seismic zone that could generate a tsunami that would impact the state and beyond, including the U.S. west coast. The effort in expanding the tsunameter network in the Pacific and to the western Atlantic, Gulf of Mexico and Caribbean required hundreds of thousands of kilometers of ship deployments. NDBC assumed operational responsibility for the tsunameter network in 2004 and the network became operational in 2005. In addition to the expansion, NDBC and its technical services contractor, SAIC, have (1) Completed the transition of the DART II technology from research to operations (2) Planned and executed 16 deployment missions needed to expand the array (3) Assisted four international partners with deployment and operation of DART II systems (4) Conducted DART II technology test procedures to facilitate and validate the commercial application of the DART II technology (5) Developed and maintain a DART observation ingest and dissemination (6) Maintained data availability in excess of the network goal of 80% (7) Introduced innovations and efficiencies in the logistics and operations that reduced the costs of maintaining the array (8) Increased the reliability of the network.