The Pacific Marine Environmental Laboratory (PMEL) has developed and installed a prototype Deep Ocean Assessment and Reporting of Tsunamis (DART) buoy array for the near real-time reporting of tsunamis in the open
ocean. DART is a component of the larger U.S. National Tsunami Hazard Mitigation Program and addresses one of the four issues identified in the Plan: Quickly Confirm Potentially Destructive Tsunamis and Reduce False
Alarms (Tsunami Hazard Mitigation Federal/State Working Group, 1996). The DART system (Fig. 1) consists of a bottom pressure recorder (BPR) that resides on the ocean floor and uses an acoustic modem to transmit data
to a moored surface buoy, which then relays the information to shore via a NOAA GOES satellite link. A DART system operates “tide” and “tsunami” mode. Tide mode sends four 15-min data points every hour to verify the
system is properly functioning. The system is tripped into tsunami mode if two 15-s water level values exceed the predicted value by a threshold limit
(usually >3 cm).