GENERAL DESCRIPTION OF DAMAGE CAUSED BY THE ATOMIC EXPLOSIONS

GENERAL DESCRIPTION OF DAMAGE CAUSED BY
THE ATOMIC EXPLOSIONS
In considering the devastation in the two cities, it should
be remembered that the cities’ differences in shape and
topography resulted in great differences in the damages.
Hiroshima was all on low, flat ground, and was roughly
circular in shape; Nagasaki was much cut up by hills and
mountain spurs, with no regularity to its shape.
In Hiroshima almost everything up to about one mile from
X was completely destroyed, except for a small number
(about 50) of heavily reinforced concrete buildings, most
of which were specially designed to withstand earthquake
shock, which were not collapsed by the blast; most of these
buildings had their interiors completely gutted, and all windows,
doors, sashes, and frames ripped out. In Nagasaki,
nearly everything within 1/2 mile of the explosion was destroyed,
including heavy structures. All Japanese homes
were destroyed within 1 1/2 miles from X.
Underground air raid shelters with earth cover roofs immediately
below the explosion had their roofs caved in;
but beyond 1/2 mile from X they suffered no damage.
In Nagasaki, 1500 feet from X high quality steel frame
buildings were not completely collapsed, but the entire
buildings suffered mass distortion and all panels and roofs
were blown in.
In Nagasaki, 2,000 feet from X, reinforced concrete build

ings with 10" walls and 6" floors were collapsed; reinforced
concrete buildings with 4" walls and roofs were standing
but were badly damaged. At 2,000 feet some 9" concrete
walls were completely destroyed.
In Nagasaki, 3,500 feet from X, church buildings with
18" brick walls were completely destroyed. 12" brick walls
were severely cracked as far as 5,000 feet.
In Hiroshima, 4,400 feet from X, multi-story brick buildings
were completely demolished. In Nagasaki, similar
buildings were destroyed to 5,300 feet.
In Hiroshima, roof tiles were bubbled (melted) by the
flash heat out to 4,000 feet from X; in Nagasaki, the same
effect was observed to 6,500 feet.
In Hiroshima, steel frame buildings were destroyed 4,200
feet from X, and to 4,800 feet in Nagasaki.
In both cities, the mass distortion of large steel buildings
was observed out to 4,500 feet from X.
In Nagasaki, reinforced concrete smoke stacks with 8"
walls, specially designed to withstand earthquake shocks,
were overturned up to 4,000 feet from X.
In Hiroshima, steel frame buildings suffered severe structural
damage up to 5,700 feet from X, and in Nagasaki the
same damage was sustained as far as 6,000 feet.
In Nagasaki, 9" brick walls were heavily cracked to 5,000
feet, were moderately cracked to 6,000 feet, and slightly
cracked to 8,000 feet. In both cities, light concrete buildings
collapsed out to 4,700 feet.
In Hiroshima, multi-story brick buildings suffered structural
damage up to 6,600 feet, and in Nagasaki up to 6,500
feet from X.
In both cities overhead electric installations were destroyed
up to 5,500 feet; and trolley cars were destroyed
up to 5,500 feet, and damaged to 10,500 feet.
Flash ignition of dry, combustible material was observed
as far as 6,400 feet from X in Hiroshima, and in Nagasaki
as far as 10,000 feet from X.
Severe damage to gas holders occured out to 6,500 feet
in both cities.
All Japanese homes were seriously damaged up to 6,500
feet in Hiroshima, and to 8,000 feet in Nagasaki. Most
Japanese homes were damaged up to 8,000 feet in
Hiroshima and 10,500 feet in Nagasaki.
The hillsides in Nagasaki were scorched by the flash radiation
of heat as far as 8,000 feet from X; this scorching
gave the hillsides the appearance of premature autumn.
In Nagasaki, very heavy plaster damage was observed in
many buildings up to 9,000 feet; moderate damage was
sustained as far as 12,000 feet, and light damage up to
15,000 feet.
The flash charring of wooden telegraph poles was observed
up to 9,500 feet from X in Hiroshima, and to 11,000
feet in Nagasaki; some reports indicate flash burns as far
as 13,000 feet from X in both places.
Severe displacement of roof tiles was observed up to

8,000 feet in Hiroshima, and to 10,000 feet in Nagasaki.
In Nagasaki, very heavy damage to window frames and
doors was observed up to 8,000 feet, and light damage up
to 12,000 feet.
Roofs and wall coverings on steel frame buildings were
destroyed out to 11,000 feet.
Although the sources of many fires were difficult to trace
accurately, it is believed that fires were started by primary
heat radiation as far as 15,000 feet from X.
Roof damage extended as far as 16,000 feet from X in
Hiroshima and in Nagasaki.
The actual collapse of buildings was observed at the extreme
range of 23,000 feet from X in Nagasaki.
Although complete window damage was observed only
up to 12,000 feet from X, some window damage occurred
in Nagasaki up to 40,000 feet, and actual breakage of glass
occured up to 60,000 feet.
Heavy fire damage was sustained in a circular area in
Hiroshima with a mean radius of about 6,000 feet and a
maximum radius of about 11,000 feet; similar heavy damage
occured in Nagasaki south of X up to 10,000 feet,
where it was stopped on a river course.
In Hiroshima over 60,000 of 90,000 buildings were destroyed
or severely damaged by the atomic bomb; this figure
represents over 67% of the city’s structures.
In Nagasaki 14,000 or 27% of 52,000 residences were
completely destroyed and 5,40O, or 10% were half destroyed.
Only 12% remained undamaged. This destruction
was limited by the layout of the city. The following is a
summary of the damage to buildings in Nagasaki as determined
from a ground survey made by the Japanese:
Destruction of Buildings and Houses
Number Percentage (Compiled by Nagasaki Municipality)
Total in Nagasaki (before atomic explosion) 50,000 100.0
Blasted (not burned) 2,652 5.3
Blasted and burned 11,494 23.0
Blasted and/or burned 14,146 28.3
Partially burned or blasted 5,441 10.9
Total buildings and houses
destroyed 19,587 39.2
Undamaged 30,413 60.8
In Hiroshima, all utilities and transportation services were
disrupted for varying lengths of time. In general however
services were restored about as rapidly as they could be
used by the depleted population. Through railroad service
was in order in Hiroshima on 8 August, and electric power
was available in most of the surviving parts on 7 August,
the day after the bombing. The reservoir of the city was
not damaged, being nearly 2 miles from X. However, 70,000
breaks in water pipes in buildings and dwellings were caused
by the blast and fire effects. Rolling transportation suffered