DART is the acronym for the Deep-ocean Assessment and Reporting of Tsunamis buoy system. Developed for tsunami warning networks, DART stations detect tiny changes in water pressure on the seafloor and transmit the measurements to warning centres.
Each station combines a bottom pressure recorder anchored on the ocean floor with a moored surface buoy. The recorder senses pressure changes caused by a passing tsunami. An acoustic link sends the information to the buoy, which relays it by satellite to ground stations and tsunami forecasters.
In normal operation, a DART station sends data at regular intervals. If unusual pressure changes are detected—or if forecasters activate the station—it switches into a faster event-reporting mode. This provides detailed information that can help confirm whether an earthquake has generated a tsunami and improve forecasts of its arrival and size.
DART is sometimes confused with GPS, radar, or sonar because all are technologies used for observation or communication. DART is the name of the tsunami-monitoring system itself; it is not simply a type of satellite, radar instrument, or general-purpose ocean buoy.