Tsunami of April 1, 1946 — Macdonald et al . 
37 
SUMMARY 
The tsunami which reached the shores of 
the Hawaiian Islands on April 1, 1946, was 
the most destructive in the history of the 
islands. Generated by a sudden shifting of 
the sea bottom on the northern slope of the 
Aleutian trough, the waves traveled south¬ 
ward to Hawaii with an average speed of 490 
miles an hour, an average wave length of 
about 122 miles, and a height over the deep 
ocean of about 2 feet. Effects on Hawaiian 
shores varied greatly. Locally the water 
dashed more than 50 feet above sea level and 
swept as much as half a mile inland. Else¬ 
where the rise in water level was very small, 
and waves were gentle. Property damage was 
heavy but loss of life was moderate. 
The heights and intensities of the waves at 
different points were influenced by position 
on the island toward or away from the source 
of the waves, offshore submarine topography, 
presence or absence of coral reefs, shore-line 
configuration, mutual reinforcement or inter¬ 
ference by waves traveling different paths, 
and the presence or absence of storm waves. 
Loss of property during future tsunamis can 
be reduced by proper construction, by erec¬ 
tion of sea walls, and by restricting or pro¬ 
hibiting construction in certain especially 
dangerous areas. Loss of life can be nearly 
or entirely eliminated by the establishment 
of a suitable system for warning of the ap¬ 
proach of waves. 
REFERENCES 
Bodle, R. R. Note on the earthquake and seismic 
sea wave of April 1, 1946. Amer. Geophys. 
Union Trans. 27: 464-465, 1946. 
Byerly, Perry. Seismology, x+256 p., 58 fig. 
Prentice-Hall, New York, 1942. 
Green, C. K. Seismic sea wave of April 1, 1946, 
as recorded on tide gages. Amer. Geophys. 
Union Trans. 27: 490-500, 1946. 
Green, George. On the motion of waves in a 
variable canal of small depth and width. Cam¬ 
bridge Phil. Soc. Trans. 6: 457-462, 1838. 
Gutenberg, Beno, and Charles F. Richter. 
Seismicity of the earth. 131 p., 17 fig. Geol. 
Soc. Amer. Spec. Paper 34. New York, 1941. 
Imamura, Akitune. Theoretical and applied 
seismology. 358 p. Tokyo, 1937. 
Jaggar, Thomas A., Jr. Hawaiian damage from 
tidal waves. Volcano Letter 321: 1-3, 1931. 
Powers, Howard A. The tidal wave of April 1, 
1946. Volcano Letter 491: 1-3, 1946. 
Shepard, Francis P., Gordon A. Macdonald, 
and Doak C. Cox. The tsunami of April 1, 
1946. [In preparation.] 
United States Navy Hydrographic Office. 
Breakers and surf. 52 p., 19 fig., 4 pi. U. S. 
Navy Hydrog. Off. Pub. 234. Washington, 
D. C., 1944. 
