customary Japanese

customary Japanese
Despite the customary Japanese lack of attention to sanitation
measures, no major epidemic broke out in the bombed
cities. Although the conditions following the bombings
makes this fact seem surprising, the experience of other
bombed cities in both Germany and Japan show Hiroshima
and Nagasaki not to be isolated cases.
The atomic explosion over Nagasaki affected an over-all
area of approximately 42.9 square miles of which about
8.5 square miles were water and only about 9.8 square
miles were built up, the remainder being partially settled.
Approximately 36% of the built up areas were seriously
damaged. The area most severely damaged had an average
radius of about 1 mile, and covered about 2.9 square miles
of which 2.4 were built up.
In Nagasaki, buildings with structural steel frames, principally
the Mitsubishi Plant as far as 6,000 feet from X
were severely damaged; these buildings were typical of
wartime mill construction in America and Great Britain,
except that some of the frames were somewhat less substantial.
The damage consisted of windows broken out
(100%), steel sashes ripped out or bent, corrugated metal
or corrugated asbestos roofs and sidings ripped off, roofs
bent or destroyed, roof trusses collapsed, columns bent
and cracked and concrete foundations for columns rotated.
Damage to buildings with structural steel frames was more
severe where the buildings received the effect of the blast
on their sides than where the blast hit the ends of buildings,
because the buildings had more stiffness (resistance to negative
moment at the top of columns) in a longitudinal direction.
Many of the lightly constructed steel frame buildings
collapsed completely while some of the heavily constructed
(to carry the weight of heavy cranes and loads) were
stripped of roof and siding, but the frames were only partially
injured.
The next most seriously damaged area in Nagasaki lies
outside the 2.9 square miles just described, and embraces
approximately 4.2 square miles of which 29% was built
up. The damage from blast and fire was moderate here,
but in some sections (portions of main business districts)
many secondary fires started and spread rapidly, resulting
in about as much over-all destruction as in areas much closer
to X.
An area of partial damage by blast and fire lies just outside
the one just described and comprises approximately
35.8 square miles. Of this area, roughly 1/6th was built up
and 1/4th was water. The extent of damage varied from
serious (severe damage to roofs and windows in the main
business section of Nagasaki, 2.5 miles from X), to minor
(broken or occasionally broken windows at a distance of 7

miles southeast of X).
As intended, the bomb was exploded at an almost ideal
location over Nagasaki to do the maximum damage to industry,
including the Mitsubishi Steel and Arms Works,
the Mitsubishi-Urakami Ordnance Works (Torpedo Works),
and numerous factories, factory training schools, and other
industrial establishments, with a minimum destruction of
dwellings and consequently, a minimum amount of casualties.
Had the bomb been dropped farther south, the
Mitsubishi-Urakami Ordnance Works would not have been
so severely damaged, but the main business and residential
districts of Nagasaki would have sustained much greater
damage casualties.
Calculations show that the structural steel and reinforced
concrete frames which survived the blast fairly close to X
could not have withstood the estimated peak pressures developed
against the total areas presented by the sides and
roof of the buildings. The survival of these frames is explained
by the fact that they were not actually required to
withstand the peak pressure because the windows were
quickly knocked out and roof and siding stripped off thereby
reducing total area and relieving the pressure. While this
saved the building frame, it permitted severe damage to building
interior and contents, and injuries to the building occupants.
Buildings without large panel openings through which
the pressure could dissipate were completely crushed, even
when their frames were as strong as those which survived.
The damage sustained by reinforced concrete buildings
depended both on the proximity to X and the type and
strength of the reinforced concrete construction. Some of
the buildings with reinforced concrete frames also had reinforced
concrete walls, ceilings, and partitions, while others
had brick or concrete tile walls covered either with
plaster or ornamental stone, with partitions of metal, glass,
and plaster. With the exception of the Nagasaki Medical
School and Hospital group, which was designed to withstand
earthquakes and was therefore of heavier construction
than most American structures, most of the reinforced
concrete structures could be classified only as fair, with
concrete of low strength and density, with many of the
columns, beams, and slabs underdesigned and improperly
reinforced. These facts account for some of the structural
failures which occured.
In general, the atomic bomb explosion damaged all windows
and ripped out, bent, or twisted most of the steel
window or door sashes, ripped doors from hinges, damaged
all suspended wood, metal, and plaster ceilings. The
blast concussion also caused great damage to equipment
by tumbling and battering. Fires generally of secondary
origin consumed practically all combustible material, caused
plaster to crack off, burned all wooden trim, stair covering,
wooden frames of wooden suspended ceilings, beds,
mattresses, and mats, and fused glass, ruined all equipment
not already destroyed by the blast, ruined all electrical wir-

ing, plumbing, and caused spalling of concrete columns
and beams in many of the rooms.
Almost without exception masonry buildings of either
brick or stone within the effective limits of the blast were
severely damaged so that most of them were flattened or
reduced to rubble. The wreckage of a church, approximately
1,800 feet east of X in Nagasaki, was one of the
few masonry buildings still recognizable and only portions
of the walls of this structure were left standing. These walls
were extremely thick (about 2 feet). The two domes of the
church had reinforced concrete frames and although they
were toppled, they held together as units.
Practically every wooden building or building with timber
frame within 2.0 miles of X was either completely destroyed
or very seriously damaged, and significant damage
in Nagasaki resulted as far as 3 miles from X. Nearly all
such buildings collapsed and a very large number were consumed
by fire.