The detonation of a single nuclear bomb or "warhead" would cause a local
disaster on a scale that few people in the world have seen and
survived. However, it should not be confused with the effects of a
nuclear war, in which many nuclear bombs would be exploded. That would
cause the end of civilization in the countries concerned, and perhaps
over the whole world, as well as radioactive contamination of whole
continents, and terrible damage to the environment and ecology.
The effect of a single bomb would depend on its power, and where it
exploded -- high in the air or at ground level -- and whether in a
densely populated and built-up area like a city or in open country like
an attack on a missile silo.
The nuclear bombs available to the great military powers of the world
(China, France, Israel, Russia, United Kingdom, United States) range in
power from several megatons down to a few kilotons (and some even
A "megaton" is the explosive power of one million tons of TNT. A
"kiloton" is the power of one thousand tons of TNT. Bombs likely to be
available to terrorist organizations or governments other than the great
military powers would be in the 10- to 100-kiloton range. Bombs made by
amateurs might not explode with the full power they were designed for.
[FOOTNOTE: TNT stands for tri-nitro-toluene, a high explosive commonly
used in shells and bombs throughout the Second World War. Weight for
weight, its explosive power is roughly equal to that of dynamite.]
The two bombs that have been exploded over cities, Hiroshima and
Nagasaki in Japan in August 1945, were in the ten- to twenty-kiloton
A ONE-MEGATON BOMB DETONATED IN THE AIR
First, we will look at the result of a single bomb of one megaton
detonated at an altitude of 2,500 metres above a city, to cause maximum
blast effects. This is believed to have been a main part of the
targeting strategy of the Soviet Union and the United States during the
"Cold War". The Russian and U.S. governments have stated that missiles
would not remain targetted on cities. However, thousands of missiles
and warheads are still deployed. They could be targetted on any city in
the world in a matter of minutes, and re-targetted to their original
targets in seconds.
Flash and fireball
The first effect of a nuclear explosion in the air is an intense flash
of light, as quick as a lightning flash but a thousand times as bright.
It is accompanied by a powerful pulse of heat radiation, sufficient to
set fire to light combustible material out to a distance of fourteen
km., and to paint or wood at half that distance. There is also an
intense pulse of X-rays, sufficient to be lethal at a distance of three
km.; in fact that would be a rather small factor, since people that
close would all or nearly all be killed by the blast that follows.
Immediately after the flash, a "fireball" forms in the air and rises for
several seconds, blindingly bright and radiating much heat. On a clear
day or night, people up to eighty km. away who happened to be facing
that way, or who turned their eyes to look where the flash came from,
would be temporarily or permanently blinded.
Within ten km. of "ground zero" (which is the point directly under the
explosion) all parts of the body exposed to the flash would be burned
deeply into the flesh. Superficial burns would be caused at greater
distances, out to fifteen km. at least. Clothing that caught fire would
cause many more burns.
The weather conditions prevailing, and the time of day the bomb
exploded, would both influence the degrees of damage. For example, the
radii for skin burns and blindness would depend on the weather. Mist or
fog reduces the range of the heat and light rays; on the other hand,
darkness dilates the pupils of the eyes increasing the probability of
severe eye damage from the flash.
Starting at the same instant, but travelling more slowly (like the sound
of thunder following a lightning flash) is an enormously powerful blast
wave. It would destroy even reinforced concrete buildings for a radius
of two km., and ordinary brick or timber frame houses out to eight km.
Major damage to houses would extend out to fourteen km., and windows
would be broken at twenty or thirty km. People at a distance, if they
realized what had happened when they saw the flash, would have a few
seconds to lie down, or even to dive into a ditch or hollow, before the
Within three km., almost everyone would be killed, either directly by
the blast or by collapsing or flying masonry. At eight km., it is
estimated that about fifty per cent of people would be killed by the
effects of the blast.
Immediately following the blast wave would be hurricane force winds,
first outwards from the explosion, and many seconds later inwards to
replace the air that went out. Within four km., the wind would be of
tornado force, six hundred km./hr., sufficient to drive straws into
wooden utility poles or glass splinters into people, but of course over
a much wider area than a tornado. People in the open would be picked up
and hurled into any object strong enough to be still standing.
Many fires would have been started by the first flash. Burst fuel
tanks, gas mains, and collapsed buildings would provide more fuel, and
it is likely that confluent fires would cause a "firestorm". This is
when coalescent fires cause sufficient updraft to form their own wind,
blowing inwards from all sides and thereby increasing the intensity of
the fire. The temperature even in basements and bomb shelters rises
above lethal levels, and all available oxygen is used by the fire.
The wind blowing inwards is of gale force, so that even strong uninjured
people would have difficulty walking or trying to run outwards away from
Delayed Radiation ("fallout")
A nuclear explosion, as well as giving off a great pulse of radiation at
the time, leaves everything in the vicinity radioactive. In the case of
an "air-burst" as just described, most of the radioactive products would
be gaseous, or completely vaporized, and would rise with the fireball
and come down slowly, if at all. There might be a rainstorm containing
radioactivity, as there was at Hiroshima; and the rubble within a
kilometre or two of the ground zero would be radioactive. This might
hamper later rescue efforts, and affect the very few survivors from that
central area, but would not be a major factor.
In any nuclear bomb explosion, a large fraction (a minimum of one-third)
of the original fissile material (plutonium or U-235) does not get
destroyed. This would result in widespread contamination, increasing the
late risk of cancer for those who survived ten to twenty years. (These
amounts of plutonium and uranium would have no immediate toxic effects.)
If the bomb exploded squarely over the centre of a city, no rescue
services within the area of major structural damage would be able to
function. All down-town hospitals would be destroyed, and there would
be no electricity, water, or telephone communication in the area served
by city utilities.
Rescue services from outside would be hampered by impassable roads and
the central area of severe damage would be inaccessible. The number of
injured in the peripheral area would be so great that emergency
services of surrounding cities would be completely overloaded, as would
be any surviving suburban hospitals and all the hospitals of
neighbouring cities. Even to be seen by a doctor and given analgesics,
the injured from one city would need to be distributed among all the
hospitals of North America.
The destroyed city would be radioactive. Decisions to attempt rescue
work would depend first on a survey of the area by a specialist team
with appropriate protection, and then on a policy decision as to how
much radiation the rescue teams should be permitted. Willingness of the
team members and their unions to accept the risk would be a final
The estimates for a city of one million or two million struck by a
single one-megaton bomb are that around one third of the inhabitants
would be killed instantly or fatally injured, one third seriously
injured, and the rest uninjured or only slightly injured. That number
of injured, if they could be distributed throughout the hospitals of
North America, would occupy something like a third of the total number
of beds; and of course no hospital can deal adequately with such an
influx of urgent cases within a few days.
There might be fifty times as many cases of severe burns as there are
burn beds in the whole of North America. A whole year's supply of blood
for transfusion would be needed immediately, and
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