

Figure 49. 



1964 tsunami runup, Kodiak City, Alaska (contours in feet); 

 heavy line is maximum flood level (from Wilson and Torum, 1968), 



An added complication, which is an important consideration in comput- 

 ing runup heights, is the possibility of storm waves occurring simultane- 

 ously with the tsunami. The prediction of maximum runup heights would 

 require the consideration of joint probabilities of tsunamis and storm 

 waves, as well as the probability of a high tidal stage. The probability 

 of a high tide, tsunami, and storm waves occurring simultaneously may 

 appear to be small; however, such an event did occur in Newfoundland in 

 1929 (Hodgson and Doxsee, 1930). 



Because a tsunami has a very long period relative to storm waves, it 

 causes an apparent variation in water depth over a long distance. Storm 

 waves riding on top the tsunami will have a wave celerity corresponding 

 to the depth (including tsunami height) at any particular point. If two 

 storm waves are otherwise equivalent (e.g., the same period and wave 



148 



