What affects effects?

Multiple factors impact what happens as a result of a nuclear detonation.

By Jill Gibson | April 2, 2024

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On July 9, 1962, Starfish Prime launched from Johnston Island and detonated 250 miles above the Pacific Ocean. The exo-atmospheric nuclear explosion generated an electromagnetic pulse (EMP) that caused streetlights to go out on the island of Oahu, 800 miles away. The test has also been credited with causing satellites to fail, including the world’s first communications satellite, Telstar, which launched the day after the Starfish detonation. Los Alamos National Laboratory

Using historical nuclear testing data and advanced computer simulations, scientists at Los Alamos National Laboratory study the way that nuclear weapons outputs interact with people, vehicles, structures, electronics, terrain, water, and air. The results of these interactions are collectively known as weapons effects

During and after a nuclear detonation, buildings may collapse. Electronics, satellites, and the power grid may fail. Fires, flash blindness, optical sensor burnout, damage to ships and underground facilities, radiation sickness, and general destruction are all possible.

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The most immediate effect of an atmospheric nuclear detonation is an intense burst of nuclear radiation. An extremely hot, spherical luminous mass, called a fireball, rises into the air.

The flash from a nuclear weapon can cause temporary blindness to unprotected eyes, even when a person is not looking directly at the detonation. Thermal radiation can cause burns directly to the skin or can ignite clothing. Prompt (initial) nuclear radiation (gamma rays and neutrons) can lead to radiation sickness and death, or at lower levels, cause cancer. The shock wave radiating outward from the detonation can cause immediate injury, death, or damage to vehicles and buildings. 

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A nuclear detonation releases thermal radiation, causing an intense blast of light and heat.


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During Operation Plumbbob Stokes, in August 1957, the air shock wave from the detonation caused an unmanned dirigible to collapse.

Nuclear Weapons Effects

Fallout: Radioactive material—usually a mix of dirt and bomb debris—that is swept into the air during a nuclear detonation and falls back to the ground. Highly radioactive fallout near the detonation location can be deadly, but its rapid decay means that most areas are not highly hazardous for long.

Prompt radiation: Radiation consisting of gamma rays and neutrons produced within a fraction of a second of detonation. Also called initial radiation, prompt radiation can be lethal to living organisms.

Thermal radiation: An intense burst of radiated heat and light that may cause flash-blindness, skin and eye burns, and fires. Fires can spread significantly beyond the detonation area.

Electromagnetic pulse (EMP): A brief burst of electromagnetic energy. The electromagnetic interference caused by an EMP can disrupt or damage communications and electronic equipment, computers, and electrical grids.

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The effects on this "Apple house" at the Nevada National Security Site include thermal radiation and air shock.

Residual radiation: Radiation produced more than one minute after the detonation, resulting from radioactive materials returning to Earth in the form of radioactive fallout.

Shock wave: A compressive pressure wave traveling faster than the speed of sound through air, water, or solid material (such as the ground).

Air shock wave (also called air blast): A shock wave in air that radiates outward from ground zero (the detonation site) and produces sudden changes in air pressure that can crush, topple, and throw objects, such as buildings, cars, and trees.

Ground shock wave:A shock wave traveling through the ground. Disturbances in the ground produced from the passing of the ground shock wave produce seismic waves. Unlike shock waves, seismic waves do not produce permanent damage to the ground.

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The effects shown here include ground and air shock waves.

Water shock wave: A shock wave traveling through the water. Disturbances in the water produced from the passing of the water shock wave produce hydroacoustic waves.

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During the Upshot-Knothole Annie test in 1953, researchers used rocket smoke trails to record the propagation of shock waves and wind currents from the explosion.



The design and explosive power of a nuclear weapon can change the impact of a nuclear detonation. Other important factors include the height of the burst above ground level, the distance of structures or living organisms from ground zero, the amount of time elapsed from the moment of detonation, and the environment in which the detonation takes place.

Residual effects and other long-term consequences may follow the initial impact of a nuclear detonation. ese may include destruction or irradiation of major population centers, contamination of the food supply, and electrical disruptions.

Height of burst: The height of the nuclear explosion relative to ground level affects the amount of thermal energy released, the fallout danger, the air shock wave strength, and the creation of an electromagnetic pulse.

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This video demonstrates height of burst.

Distance from detonation: Damage will vary based on distance from ground zero. Destruction, radiation, and injury will be most severe closest to ground zero.

Elapsed time: As time passes, the effects will transition from initial to residual.

Yield: The explosive power of the detonation. Yield is usually measured in terms of the amount of conventional explosives (TNT) that would be required to produce a similar amount of energy. For example, the 21-kiloton Trinity test was equivalent to 21 thousand tons of TNT.

Detonation Environment

Detonations may take place aboveground (called atmospheric detonations), underground, underwater, or in space. The geographic location in which the detonation takes place significantly impacts effects. Topography—such as canyons and mountains—as well as cities and weather can change effects.

Detonation Environment@2x


Nuclear weapons detonations in space create radiation and may generate a burst of electromagnetic energy called an electromagnetic pulse (EMP).


The most immediate effect of an explosion in the air above the Earth’s surface is an intense burst of nuclear radiation, primarily gamma rays and neutrons. An extremely hot, spherical, luminous mass, called a fireball, rises into the air. A shock wave travels away from the fireball. A detonation located closer to ground level will send more debris into the air, resulting in significantly more fallout.


Detonations underwater may create an underwater shock wave, a water plume, radioactive water, and steam.


An underground detonation may create craters on the Earth’s surface directly above where the device is buried. These subsidence craters form when an explosion creates a cavity into which the surface soil sinks. The craters vary in size and depth depending on what type of soil or rock the device is buried in, the device’s yield, and the depth of the device. Depending on the depth and containment of the explosion, little or no radiation will be released into the atmosphere—but radiation will exist underground. 

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This video shows the formation of a subsidence crater.