34 
PACIFIC SCIENCE, January, 1947 
in the small bay just south of Hanamaulu 
Bay, on the eastern shore of Kauai, the water 
rose only 25 feet on the bay sides, but swept 
up the small valley at its head to a height 
of 40 feet. At Moloaa, on Kauai, the water 
reached an altitude of 40 feet in the axis of 
the valley, but only 30 to 35 feet on the bay 
walls. Again, at Honouliwai, on Molokai, 
the water reached a height of 27 feet oppo¬ 
site the beach, but went 6 feet higher up the 
valley. These are merely specialized exam¬ 
ples of effect, upon the rush of water up on 
shore, of a topography above sea level which 
served to concentrate the inrushing water. 
Merging of waves from different directions. 
—Wave crests traveling by different routes 
may arrive at a given locality simultaneously, 
giving rise to a wave of greater size than 
either. Likewise, the simultaneous arrival by 
different routes of a wave crest and a wave 
trough may effectually cancel out both. Thus, 
variations in the size and intensity of waves, 
particularly on the sides of the islands away 
from the wave origin, may result from the 
arrival, either in or out of phase, of two 
wave trains. During the tsunami of 1946 
several examples of the formation of a large 
wave by the juncture of two smaller ones 
were observed. Thus, in the Keaukaha area 
east of Hilo, witnesses described the arrival 
of a wave from the north simultaneously 
with one from the northeast, which built up 
a very high crest at the place of juncture. 
At the head of Maunalua Bay, on the south¬ 
eastern shore of Oahu, two waves were seen 
to advance up channels across the wide reef, 
move toward each other parallel with the 
shore, and meet, throwing water upward like 
the spray from a geyser. The water dashed 
up on shore to a height of only 3 feet except 
at the place of juncture, where it swept over 
the top of a sandspit 5 feet above sea level. 
Progressively southward around the shores 
of Kauai, the average height of the high- 
water marks gradually decreases, and along 
much of the southern shore it is 6 to 12 feet 
above sea level. However, in a zone 3 or 4 
miles wide it ranges from 15 to 18 feet. This 
zone is almost directly across the island from 
the direction of wave origin, and probably 
represents the area in which the waves re¬ 
fracted around opposite sides of the island 
met and reinforced each other. 
DAMAGE BY THE TSUNAMI 
Damage by the tsunami can be divided 
into structural damage, damage by erosion 
and deposition, and damage by flooding. The 
total property damage has been estimated 
by the office of the Governor, Territory of 
Hawaii, at about $25,000,000. Space per¬ 
mits only a brief review of the types of dam¬ 
age. The numbers of dwellings destroyed 
and damaged by the tsunami on the major 
islands are listed in Table 2 on page 36. 
Structural damage includes damage to 
buildings, roads, railroads, bridges, piers, 
breakwaters, fishpond walls, and ships. 
Frame buildings at low altitudes along 
Hawaiian shores suffered extensive dam¬ 
age. Some were knocked over, by the force 
of the waves, by cutting away of the sand on 
which they stood, or by destruction of the 
foundations. Others were bodily washed 
away from their foundations. Some had 
walls pushed in by the force of the water, 
and in a few residences the water went on 
through the house and took out the opposite 
wall. As with earthquakes, there was a tend¬ 
ency to reduce the few two-story buildings 
to a single story, by destruction of the lower 
story. It is noteworthy that houses which 
were well built and tied together internally 
could be moved for considerable distances 
without suffering severe damage. Even more 
striking was the fact that houses elevated on 
stilts a foot to several feet above the ground 
survived the waves much more effectively 
than did those built directly on the ground. 
Apparently the water was able to pass under 
such houses without greatly disturbing them, 
unless it was deep enough actually to float 
