Inquiries are sent to tide stations near the earthquake epicenter to 

 determine if tsunami waves have been generated. If there is reasonable 

 cause to assume that a tsunami may have been generated (based on seismic 

 records or observations at tide stations), an advisory bulletin is issued 

 giving estimated times of arrival (ETA's) of the tsunami at various 

 coastal points. 



The Honolulu Observatory continues to receive reports and issue 

 bulletins to Civil Defense agencies as information becomes available. 

 Various agencies are kept advised of the status of the tsunami until an 

 all-clear bulletin is issued. If a tsunami was generated, various report- 

 ing stations continue to report water levels to the Honolulu Observatory 

 until all information has been obtained from the tide stations of the 

 Tsunami Warning System in the Pacific. 



Cox (1964) indicates that tsunami warnings, as distinct from advisory 

 bulletins, are issued only under the following circumstances: 



(a) Unusual sea level disturbances having tsunami character- 

 istics are recorded at one or more of the warning system tide 

 stations scattered about the Pacific. 



(b) No reply is received from a tide station in a critical 

 recording position in response to a query from the Honolulu 

 Observatory after the occurrence of an earthquake large enough 

 to trigger the seismograph alarm. 



(c) An earthquake occurs whose epicenter is in or on the 

 borders of the Pacific Ocean in such a location that a tsunami 

 generated there would not arrive at any tide stations sufficiently 

 in advance of its arrival at a particular shoreline to allow warn- 

 ing that shoreline. 



It is the responsibility of agencies receiving tsunami warnings to 

 disseminate information to the civilian population. This may be done 

 through broadcasting news media (radio and television), by police and 

 civil defense personnel, or by sounding signals on sirens. Schank (1978) 

 discusses the public warning system in the State of Hawaii. Broadcasters 

 in the State are linked together in a system called "Civ -Alert." If it 

 is considered probable that a tsunami will cause property damage and loss 

 of life, a tsunami alert is given. The first alert is given 2 hours 

 before the estimated ETA by sounding an alert on all of the sirens in 

 the State. Civ-Alert broadcasts information and instructions. The alert 

 is repeated at 1 hour and then a half hour before the estimated ETA. The 

 alert is extended by police, fire, forestry, and Civil Air Patrol person- 

 nel. Maps of potential tsunami hazard areas are included in the county 

 telephone directories in Hawaii to define areas which should be evacuated, 



Cox (1978) considered the cost of false alarms, i.e., tsunami alerts 

 when no significant tsunami occurs, giving the cost of false alarms at 

 $264,000 per year (1977) in Hawaii alone. The cost of false alarms must 



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