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Tsunami Warning and Preparedness: An Assessment of the U.S. Tsunami Program
wave amplitude listed, which confirmed the generation of a tsunami. Nevertheless, the official evaluation stated that “Based on available data a tsunami may have been generated….”2
After the second message, 86 minutes later, Tsunami Message Number 3 was issued at 10:23 AM HST. The tsunami watch was officially canceled in this announcement for the entire state of Hawaii, and was replaced with a tsunami advisory. This message was updated with a significant amount of information available from additional gauge stations. It was determined, as listed in the evaluation, that a major tsunami would not strike the state of Hawaii, but that a sea level change and stronger currents were possible, which could be hazardous to people along the coastlines. The estimated time that the effects from the sea level change and stronger currents could be expected to begin was 1:00 PM HST. Based on these hazards, it was stated that the tsunami advisory would remain in effect until 7:00 PM HST.2 Due to the timely delivery of this message, an evacuation was avoided.
An announcement issued by Civil Defense was delivered by police, fire, and lifeguards to the public warning it of potential risks on beaches and suggesting that people remain out of the water.3,4 Despite Civil Defense’s announcement that beach goers should remain out of the water during the time of the possible arrival of the first wave, from 1:11 p.m. and onward, it was reported that Waikiki Beaches were still packed with people during this time.3 Because Civil Defense knew and communicated that a widespread evacuation was not necessary, people were unresponsive to suggestions that they remain out of the water.
The fourth and final tsunami message, issued at 4:12 PM HST, announced the continuation of the tsunami advisory for the state of Hawaii. This message provided more detail from additional gauge stations with latitude, longitude, time, amplitude, and the wave period for tsunami wave activity. The evaluation in this message declared that “Small tsunami waves from this earthquake are now crossing the Hawaiian Islands. While these waves are not expected to cause any significant coastal flooding they can produce small changes of sea level at the coast and strong or unusual currents that can be hazardous to swimmers.”2
1. National Oceanic and Atmospheric Administration. 2009. Pacific Tsunami Warning Center Tsunami Bulletins to IOC listserv. Pacific Tsunami Warning Center, National Oceanic and Atmospheric Administration, Ewa Beach, Hawaii.
2. National Oceanic and Atmospheric Administration. 2009. Pacific Tsunami Warning Center Tsunami Messages to CivilDefense. Pacific Tsunami Warning Center, National Oceanic and Atmospheric Administration, Ewa Beach, Hawaii.