36 
PACIFIC SCIENCE, January, 1947 
district in Japan, which took more than 
27,000 lives (Byerly, 1942: 72). 
TABLE 2 
List of Casualties during the Tsunami of 
April 1 , 1946 
ISLAND 
KNOWN 
DEAD 
MISS¬ 
ING 
IN¬ 
JURED* 
HOMES 
DEMOL- 
ISHEDf 
HOMES 
DAM- 
AGEDf 
Hawaii 
87 
34 
153 
283 
313 
Maui 
9 
5 
2 
65 
144 
Oahu 
9 
0 
0 
67 
335 
Molokai 
0 
0 
0 
13 
14 
Kauai 
10 
5 
8 
60 
130 
Total 
115 
44 
163 
488 
936 
159 
* Injury sufficiently serious to require hospitalization, 
f Homes only; other buildings not included. Data from 
Lewers and Cooke, Ltd. 
MITIGATION OF DISASTERS RESULTING 
FROM FUTURE TSUNAMIS 
There is no Hawaiian shore which is ex¬ 
empt from tsunamis. The most likely sources 
of devastating tsunamis are the North Pacific 
and South America. The areas heavily hit by 
the 1946 tsunami are probably those most 
likely to be hit hard again by tsunamis from 
the North Pacific. Violent tsunamis from 
Central or South America might, however, 
cause much more damage than did the 1946 
tsunami along eastern and southern coasts. 
There is also possibility of serious damage 
on western shores by a tsunami from Japan, 
particularly if the tsunami occurred during 
a heavy southwesterly storm. Tsunamis of 
local origin might do heavy damage on any 
shore. 
It is obviously impractical to consider the 
removal of all dwellings from Hawaiian 
shores because of the danger from tsunamis. 
It might, however, be advisable to prevent or 
restrict building in certain areas of greatest 
danger, particularly in centers of heavy pop¬ 
ulation, such as the waterfront at Hilo. Con¬ 
struction of suitable sea walls might also be 
advisable in places. Sea walls cannot, how¬ 
ever, be built high and strong enough to hold 
the water back completely, and an open zone 
should be left back of the wall in which the 
water pouring over the wall can use up its 
energy in turbulence. Any construction per¬ 
mitted in such areas should be of a wave- 
resistant type, such as reinforced concrete. 
These wave-resistant buildings would have 
the added virtue of serving as a line of de¬ 
fense for frailer structures behind them. 
Frame structures in rural areas should be 
built up off the ground, and far enough back 
from the edge of the beach to reduce the 
danger of undercutting. They should also be 
properly reinforced and tied together. 
It appears inevitable that future tsunamis 
will cause loss of property on Hawaiian 
shores, but loss of life from all except tsu¬ 
namis of local origin could be largely or en¬ 
tirely avoided. A system of stations could be 
established around the shores of the Pacific 
and on mid-Pacific islands, which would ob¬ 
serve either visually or instrumentally the 
arrival of large long waves of the periods 
characterizing tsunamis. The arrival of these 
waves should be reported immediately to a 
central station, whose duty it would be to 
correlate the reports and issue warnings to 
places in the path of the waves. It should be 
possible in this way to give the people of the 
Hawaiian Islands enough warning of the ap¬ 
proach of a tsunami to permit them to reach 
places of safety. The effectiveness of the 
warning, however, would depend on educa¬ 
tion of the public on the necessity for leaving 
areas of danger, and on the efficiency of the 
local organization in spreading the warning 
and evacuating the threatened areas. Event¬ 
ually it should also be possible to state, at the 
same time, which areas are likely to suffer the 
most damage. Before that can be done, how¬ 
ever, we need more knowledge of the be¬ 
havior of tsunamis on Hawaiian shores, par¬ 
ticularly tsunamis from sources in the east¬ 
ern and western Pacific, and a more complete 
picture of the submarine topography around 
the Hawaiian Islands. 
