Deep-ocean Assessment and Reporting of Tsunamis

The Deep-ocean Assessment and Reporting of Tsunamis (officially abbreviated and trademarked as DART) system is a component of an enhanced tsunami warning system.

Each DART station consists of a surface buoy and a seafloor bottom pressure recording (BPR) package that detects pressure changes caused by tsunamis. The surface buoy receives transmitted information from the BPR via an acoustic link and then transmits data to a satellite, which retransmits the data to ground stations for immediate dissemination to NOAA's Tsunami Warning Centers, NOAA's National Data Buoy Center, and NOAA's Pacific Marine Environmental Laboratory (PMEL). The Iridium commercial satellite phone network is used for communication between 31 of the buoys.

When on-board software identifies a possible tsunami, the station leaves standard mode and begins transmitting in event mode. In standard mode, the station reports water temperature and pressure (which are converted to sea-surface height) every 15 minutes. At the start of event mode, the buoy reports measurements every 15 seconds for several minutes, followed by 1-minute averages for 4 hours.

The first-generation DART I stations had one-way communication ability, and relied solely on the software's ability to detect a tsunami to trigger event mode and rapid data transmission. In order to avoid false positives, the detection threshold was set relatively high, presenting the possibility that a tsunami with a low amplitude could fail to trigger the station.

The second-generation DART II is equipped for two-way communication, allowing tsunami forecasters to place the station in event mode in anticipation of a tsunami's arrival.

National Oceanic and Atmospheric Administration’s NOAA have placed Deep-ocean Assessment and Reporting of Tsunami stations in particular areas, areas with a history of generating large tsunamis, to be completely positive that the detection of tsunamis are to be as fast as possible. The year of 2001 was the completion of the first six tsunami detection buoys placed along the northern Pacific Ocean coast. In 2005 the United States president George W. Bush announced a two-year, $3.5 million, plan to install tsunami detecting buoys in the Atlantic and the Caribbean ocean in order to expand the nation’s capabilities to detect tsunamis. With the Pacific Ocean creating 85 percent of the world’s tsunamis , the majority of new tsunami detecting buoy equipment will be installed around the pacific rim, while only seven buoys will be placed along the Atlantic and Caribbean coast because even though tsunamis are rare in the Atlantic, there have been records of deadly tsunamis being reported in the Atlantic. Roughly $13.8 million of the governments funding was used to procure and install exactly 32 pressure sensors on the ocean bottom to detect tsunamis and collect data such as the height and speed of the approaching tsunami. This proposed system, stated by the John H. Marburger the White House’s Office of Science and Technology Policy, should provide the United States’ Tsunami Warning Centers with nearly one hundred percent coverage for any approaching tsunamis as well as decline all false alarms to just about zero. During all these improvements and upgrades of the current system, roughly three fourths of the tsunami warnings were discovered to be unnecessary and a waste of money. A few years later in 2008 there are now roughly 40 tsunami detection buoys placed in the Pacific Ocean by NOAA. The upgraded DART buoys were originally developed to maintain but to mostly improve the timing of detection of a tsunami. With an improved detection time for tsunamis, that is more time to save lives, warning guidance and international coordination.

...
Wikipedia