The Tsunami of April 1, 1946, in the Hawaiian Islands 
G. A. Macdonald, F. P, Shepard, and D. C. Cox 1 
INTRODUCTION 
The tsunami which struck the shores of 
the Hawaiian Islands on the morning of 
April 1, 1946, was the most destructive, and 
one of the most violent, in the history of the 
islands. More than 150 persons were killed, 
principally by drowning, and at least 161 
others were injured. Property damage 
reached about $25,000,000. 
The wave attack on Hawaiian shores was 
far from uniform. The height and violence 
of the waves at adjacent points varied greatly, 
and not always in the manner which would 
have been expected from superficial inspec¬ 
tion and a study of the existing literature on 
tsunamis. Therefore, a detailed study of the 
effects of the tsunami has been made, in an 
effort to understand the observed variations, 
and in the hope that the principles estab¬ 
lished may help lessen the loss of life and 
property in future tsunamis. Space is not 
available in the present short paper to discuss 
findings in detail, or even to present all the 
evidence for all the conclusions. These mat¬ 
ters will be treated in detail in a longer paper 
(Shepard, Cox, and Macdonald, in prepara¬ 
tion) . 
Acknowledgments: We wish to thank the 
many persons who furnished information 
during the course of the field study. We are 
also especially grateful to M. H. Carson, H. 
S. Leak, H. W. Beardin, and W. K. Sproat, 
who supplied measurements of the high- 
1 U. S. Geological Survey, Scripps Institution of 
Oceanography, and Hawaiian Sugar Planters’ As¬ 
sociation Experiment Station, respectively. This 
paper is published by permission of the Director, 
Geological Survey, U. S. Department of the In¬ 
terior. 
water level in areas not visited by us; H. W. 
Iversen and J. D. Isaacs, who supplied addi¬ 
tional measurements on Oahu; A. F. Robin¬ 
son and Dexter Fraser, who furnished de¬ 
scriptions of the wave effects on Niihau and 
Lanai, respectively; the Hawaii County Engi¬ 
neer’s Office, which supplied a map showing 
the extent of flooding in Hilo; and the U. S. 
Coast and Geodetic Survey, which supplied 
data on the earthquake and the record of the 
Honolulu tide gage, and permitted the use, 
in advance of publication, of C. K. Green’s 
manuscript on the tsunami along the shores 
of North and South America. Howard A. 
Powers, Seismologist of the Volcano Obser¬ 
vatory at Hawaii National Park, aided greatly 
in the investigation on the island of Hawaii. 
Miss Maude Jones, Archivist of the Territory 
of Hawaii, and Miss Margaret Titcomb, 
Librarian of the Bishop Museum, aided in 
locating records of past waves. C. K. Went¬ 
worth and H. S. Palmer aided greatly in dis¬ 
cussions. Wentworth and Walter Munk 
read and criticized the manuscript. J. Y. 
Nitta prepared the illustrations. 
DEFINITION OF "TSUNAMI” 
The name 'Tsunami” 2 is applied to a long- 
period gravity wave in the ocean caused by a 
sudden large displacement of the sea bottom 
or shores. A tsunami is accompanied by a 
severe earthquake, but the earthquake does 
not cause the tsunami. Rather, both are 
caused by the same sudden crustal displace¬ 
ment. The waves of a tsunami have a period 
2 Also spelled "tunami,” the Japanese equivalent 
of the letter / being pronounced ts in English. It 
appears preferable, however, to use the phonetic 
spelling in English, avoiding thereby much incor¬ 
rect pronunciation. 
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