slopes, the wave length shortens and the height of the wave 

 increases. In general it is noted on the shore as a series 

 of rapid changes in sea level with the troughs exposing large 

 areas offshore and the crests inundating coastal areas. 



Ships have been carried well inland and left high and 

 dry, structures have been lifted off their foundations and 

 swept to sea, and people have been carried to sea or struck 

 by floating debris. Thus tsunamis have caused significant 

 loss of life and property damage. 



Figures 13, 14, and 15 are copies of tide gauge records 

 for Crescent City (California), Caldera (Chile) and Acapulco 

 (Mexico) for the same tsunami. The period and shape of the 

 tsunami records at these stations are quite different. A 

 study of spectra for several tsunamis at different locations 

 demonstrated that certain frequencies at each location appear 

 to be augmented for all tsunamis. Figures l6 and 17, spectra 

 for Honolulu and Santa Monica tsunami records for the same 

 two tsunamis, indicate that the spectra of energy for differ- 

 ent tsunamis at the same location tend to be parallel where- 

 as the spectra for the same tsunami at different locations 

 tend to be quite different. This supports the suggestion 

 that the wave is severely distorted by the response char- 

 acteristics of local bathymetry. 



Considerable priority in tsunami research has been 

 assigned to developing a system for measuring a tsunami in 



26-23 



