National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 1997

Real-time tsunami reporting from the deep ocean

Milburn, H.B., A.I. Nakamura, and F.I. González

In Proceedings of the Oceans 96 MTS/IEEE Conference, Fort Lauderdale, FL, 23–26 September 1996, 390–394 (1996)

A 100-year historical database indicates that an average of five tsunamis per year occur in the Pacific and that during this period tsunamis have killed more than 50,000 people [1]. At present, U.S. coastal communities receive warnings based on shore-based seismic data and information from coastal sea level stations. An unacceptable 75% false alarm rate has prevailed. Direct measurement of tsunamis in the open ocean, followed by real-time reports to warning centers, could improve the assessment of the tsunami hazard. Tsunamis have been observed in the deep ocean as part of a research program; furthermore, a recent successful demonstration of a near real-time system has been completed. A surface mooring was deployed with an acoustic modem and a bottom pressure recorder in 2600 m of water. Pressure data was remotely collected from the seafloor via the acoustic modem and telemetered to shore via satellite. The deployment of an array of these moorings in the Pacific is under consideration.

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