Warning Dissemination Research Activities

Warning Dissemination

• Tsunami watch, warning and information bulletins issued by PTWC and WCATWC are disseminated to local, state, national and international users as well as the media. These users, in turn, disseminate the tsunami information to the public, generally over commercial radio and television channels.
• The NOAA Weather Radio system, based on a large number of VHF transmitter sites, provides direct broadcast of tsunami information to the public.
• The U.S. Coast Guard also broadcasts urgent marine warnings and related tsunami information to coastal users equipped with medium frequency (MF) and very high frequency (VHF) marine radios.
• Local authorities and emergency managers are responsible for formulating and executing evacuation plans for areas under a tsunami warning. The public should stay-tuned to the local media for evacuation orders should tsunami warning be issued. And, the public should NOT RETURN to low lying areas until the tsunami threat has passed and the "all clear" is announced by the local authorities.

Tsunami Research Activities

With the broad availability of relatively inexpensive yet powerful computers and desk-top workstations, there is growing interest and activity in tsunami research. Using the latest in computer technology, scientists are able to numerically model tsunami generation, open ocean propagation and coastal runup. Recent advances in the technology have led to improved propagation and runup models.

Sub-surface pressure sensors, able to measure tsunamis in the open ocean, are providing important data on the propagation of tsunamis in deep water. Unfortunately, the mechanism of tsunami generation is not well understood.

Seismologists, studying the dynamics of earthquakes, are formulating new methods to analyze earthquake motion and the amount of energy released. Where the traditional Richter (surface wave) magnitude of earthquakes is not accurate above 7.5, the seismic moment is designed to better define the amount of energy released and the potential for tsunami generation. It is hoped that this relationship between seismic moment and the potential for tsunami generation can be refined so that the near-real time analysis of earthquakes can be performed for tsunami warning purposes.

Tsunami inundation models, defining the extent of coastal flooding, are an integral aspect of tsunami hazard and preparedness planning. Using worst case inundation scenarios, these models are critical to defining evacuation zones and routes so that coastal communities can be evacuated quickly when a tsunami warning has been issued. NOAA's Pacific Marine Environmental Laboratory is taking a lead role in developing tsunami inundation maps for coastal communities in Alaska, California, Hawaii, Oregon and Washington states.

In the area of improved tsunami wave detection instrumentation, recording systems comprised of sub-surface pressure sensors have been tested over the last decade off the Alaska and Oregon coasts. These pressure sensors, located on the sea floor, have successfully measured tsunami wave amplitudes in the open ocean. The final step in developing a deep water tsunami wave detection system for warning purposes brings together the collection of the pressure data and its subsequent rapid, reliable telemetry to the shore-based warning center. Open ocean tsunami wave detection systems using satellite or radio telemetry are being tested off the California coast.

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