TSUNAMI OF APRIL 1, 194 6 — MACDONALD, ET AL. 



265 



means of tide tables to height above lower low water. Some inaccuracy 

 undoubtedly has entered in the estimation of mean sea level, but it 

 is believed that the heights are probably accurate to within 1 foot. The 

 levels measured include : points indicated by eyewitnesses as the upper 

 limit of the water, lines of flotsam or swash marks, the upper limits 

 of soil and vegetation scouring, levels of consistent scratching and 

 barking on trees, and the upper level of staining on the walls of 

 buildings. 



FiGUitE 3. — Map of the island of Kauai, showing heights reached by the water 

 during the tsunami of April 1, 1946. Heights are in feet above lower low 

 water. 



The measured heights of high-water marks range from 55 feet at 

 Pololu Valley on Hawaii, 54 feet at Waikolu Valley on Molokai, and 

 45 feet at Haena and Kilauea Point on Kauai, to 2 feet at Kaunakakai 

 on Molokai, 2 feet at Milolii and Hoopuloa on Hawaii, and less than 

 2 feet at the head of Kaneohe Bay on Oahu. Causes of the variations 

 in height will be discussed in a later section. 



Most of the heights measured are, of course, not the heights of the 

 actual waves, but rather the heights to which the water was driven 

 on shore. On a vertical clilBF directly across the path of the wave, this 

 height may theoretically amount to twice the height of the actual 

 wave. On slopes less than vertical, or on cliffs at an angle to the 



