50. Can "tidal" waves be forecast? 



Yes, "tidal" waves (tsunamis) can be forecast, because the earth- 

 quake waves causing them cross the ocean in only a few minutes and 

 can be picked up by seismograph stations hours before the sea wave 

 arrives. 



After the destructive tsunami that struck the Hawaiian Islands in 

 1946, killing 173 people and destroying 25 million dollars worth of 

 property, a warning system was set up in the Pacific. Seismograph sta- 

 tions provide information on the time and location of the quake. If the 

 epicenter of the quake is under the sea, a tsunami may result. When a 

 quake is noted, tide stations are alerted to watch for indications of a 

 wave. 



A travel time chart centered on the Hawaiian Islands is used to esti- 

 mate time of arrival of the waves. Warnings of estimated time of arrival 

 are transmitted through an international Pacific-wide communication 

 system. The U. S. Coast and Geodetic Survey operates the warning 

 service, which has its headquarters in Honolulu, Hawaii. 



Bowdltch, Nathaniel 



American Practical Navigator, U. S. Naval Oceanographic Office, 



1958. 

 Gaskell, T. F. 



World Berjeath the Oceans, American Museum of Natural History, 



1964. 

 U. S. Coast and Geodetic Survey 



Tsunami, The Story of the Seismic Sea-Wave Warning System, 1 965. 



58 



