National Oceanic and
Atmospheric Administration
United States Department of Commerce


FY 1988

A tsunami early warning system—Summary

Bernard, E.N., R.R. Behn, and H.B. Milburn

In Proceedings of the International Tsunami Symposium, International Union of Geodesy and Geophysics, Vancouver, B.C., Canada, 18–19 August 1987, 276–290 (1988)

A pilot local (100 km) tsunami warning system has been developed to deliver tsunami warning information within 2 minutes of earthquake origin time. Tsunami Hazards Reduction Utilizing Systems Technology (THRUST) system was installed in Valparaiso, Chile to evaluate its value in mitigating tsunami hazards in countries without regional warning systems. The satellite-linked system consists of a pre-tsunami preparedness program and real-time data collection and information dissemination instruments. To develop the preparedness program, an examination of past tsunami wave heights supplemented by numerical simulations of potential tsunamis provided the basis for evacuation areas in Valparaiso's emergency operations plan. Instruments used to collect geophysical data include an accelerometer to measure earthquake intensity and a water pressure gauge to measure tsunami activity. Once the acceleration threshold has been exceeded, a signal is transmitted that prompts the GOES satellite to automatically broadcast an alert message. Receivers in Valparaiso and other warning locations under the GOES communications coverage (Honolulu, Hawaii; Seattle, Washington; and Boulder, Colorado) continuously monitor the satellite for this alert message and take predetermined action once received. Cost for the essential THRUST equipment is about $15,000, exclusive of installation. Evaluation of the real-time equipment over a 1-year test revealed an average communications time of 1.6 minutes from accelerometer signal to printed message at the receiver site and an equipment reliability factor in excess of 90%. THRUST is an example of a systems approach to natural hazards mitigation management that blends new technologies with existing operations for the benefit of affected populations.

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