residential section of Nagasaki.

“Outside a radius of 2 kilometers and within a radius of 4
kilometers from X, men and animals suffered various degrees
of injury from window glass and other fragments
scattered about by the blast and many were burned by the
intense heat. Dwellings and other structures were half damaged
by blast.
“Outside a radius of 4 kilometers and within a radius of 8
kilometers living creatures were injured by materials blown
about by the blast; the majority were only superficially
wounded. Houses were only half or partially damaged.”
The British Mission to Japan interpreted their observations
of the destruction of buildings to apply to similar construction
of their own as follows:
A similar bomb exploding in a similar fashion would produce
the following effects on normal British houses:
Up to 1,000 yards from X it would cause complete collapse.
Up to 1 mile from X it would damage the houses beyond
repair.
Up to 1.5 miles from X it would render them uninhabitable
without extensive repair, particularly to roof timbers.
Up to 2.5 miles from X it would render them uninhabitable
until first-aid repairs had been carried out.
The fire damage in both cities was tremendous, but was
more complete in Hiroshima than in Nagasaki. The effect
of the fires was to change profoundly the appearance of
the city and to leave the central part bare, except for some
reinforced concrete and steel frames and objects such as

safes, chimney stacks, and pieces of twisted sheet metal.
The fire damage resulted more from the properties of the
cities themselves than from those of the bombs.
The conflagration in Hiroshima caused high winds to
spring up as air was drawn in toward the center of the
burning area, creating a “fire storm”. The wind velocity in
the city had been less than 5 miles per hour before the bombing,
but the fire-wind attained a velocity of 30-40 miles per
hour. These great winds restricted the perimeter of the fire
but greatly added to the damage of the conflagration within
the perimeter and caused the deaths of many persons who
might otherwise have escaped. In Nagasaki, very severe
damage was caused by fires, but no extensive “fire storm”
engulfed the city. In both cities, some of the fires close to
X were no doubt started by the ignition of highly combustible
material such as paper, straw, and dry cloth, upon the
instantaneous radiation of heat from the nuclear explosion.
The presence of large amounts of unburnt combustible
materials near X, however, indicated that even though the
heat of the blast was very intense, its duration was insufficient
to raise the temperature of many materials to the kindling
point except in cases where conditions were ideal.
The majority of the fires were of secondary origin starting
from the usual electrical short-circuits, broken gas lines,
overturned stoves, open fires, charcoal braziers, lamps, etc.,
following collapse or serious damage from the direct blast.
Fire fighting and rescue units were stripped of men and
equipment. Almost 30 hours elapsed before any rescue
parties were observable. In Hiroshima only a handful of
fire engines were available for fighting the ensuing fires,
and none of these were of first class type. In any case,
however, it is not likely that any fire fighting equipment or
personnel or organization could have effected any significant
reduction in the amount of damage caused by the tremendous
conflagration.
A study of numerous aerial photographs made prior to
the atomic bombings indicates that between 10 June and 9
August 1945 the Japanese constructed fire breaks in certain
areas of the cities in order to control large scale fires.
In general these fire breaks were not effective because fires
were started at so many locations simultaneously. They
appear, however, to have helped prevent fires from spreading
farther east into the main business and residential section
of Nagasaki.