B83 on Cairo
1.2 Mt thermonuclear weapon · Egypt · Population 9,540,000 · Density 19,000/km²
About this scenario
This page calculates what would happen if the B83 (USA, 1983) detonated over Cairo (Egypt). Most powerful US weapon in active service.
The capital of Egypt and the largest city in the Arab world; the Greater Cairo region holds over 21 million. With an urban-core density of about 19,000 people per km², even a relatively small detonation over the city center would affect a large population.
The B83 delivers 1.2 Mt of explosive yield — 80× more powerful than the Hiroshima bomb. The tables below show calculated effect radii for an air burst (optimized for blast spread) and a surface burst (which produces massive fallout).
Air-burst effects (B83 over Cairo)
| Effect zone | Radius | Est. affected |
|---|---|---|
| Fireball (vaporization, 100% fatal) | 2.47 km | ~364,741 |
| Severe blast (20 PSI, ~98% fatal) | 5.00 km | ~1,099,064 |
| Moderate blast (5 PSI, ~50% fatal) | 10.69 km | ~2,663,579 |
| Light blast (1 PSI, glass injuries) | 30.41 km | ~2,418,699 |
| 3rd-degree thermal burns | 12.26 km | — |
| 2nd-degree thermal burns | 21.96 km | — |
Estimated total fatalities: ~4,127,384 · Estimated total affected (inside 1 PSI light-blast radius): ~55,194,822.
Surface-burst effects (with fallout)
A surface burst trades blast spread for radioactive fallout — much smaller blast radii but a large lethal fallout plume drifting downwind. This is what would happen if the B83 struck ground level rather than detonating optimally above Cairo.
| Effect zone | Radius (surface burst) |
|---|---|
| Fireball | 1.98 km |
| Severe blast (20 PSI) | 2.75 km |
| Moderate blast (5 PSI) | 5.88 km |
| Light blast (1 PSI) | 16.72 km |
| 3rd-degree thermal burns | 7.36 km |
| Lethal fallout zone | ~204.6 km |
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See the actual blast zones overlaid on a map of Cairo with population-density-based casualty estimates updated in real time as you move the detonation point.
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FAQ
What would happen if the B83 detonated over Cairo?
In an air burst over Cairo, the B83 (1.2 Mt) would produce a fireball about 2.47 km in radius. The 5 PSI moderate-blast zone — where most residential buildings collapse — would extend to 10.69 km. Light blast damage and shattered windows would reach 30.41 km. Given Cairo's urban density (~19,000/km²), this scenario yields an estimated 4,127,384 immediate fatalities and about 2,418,699 additional injured.
How many people would die in Cairo from a B83 strike?
An air burst of the B83 over Cairo could cause an estimated 4,127,384 immediate fatalities and 2,418,699 additional injuries. The fireball alone (radius 2.47 km) would kill approximately 364,741 people; the severe-blast zone (20 PSI, radius 5.00 km) would add 1,099,064; the moderate-blast zone (5 PSI, radius 10.69 km) would add 2,663,579 more. Real numbers depend heavily on time of day, sheltering, weather, and altitude of detonation.
What is the blast radius of the B83 on Cairo?
For an air burst over Cairo: fireball 2.47 km, severe blast (20 PSI) 5.00 km, moderate blast (5 PSI) 10.69 km, light blast (1 PSI) 30.41 km. Thermal radiation causes 3rd-degree burns out to 12.26 km. A surface burst would shrink the blast radii by roughly 40 percent but generate massive radioactive fallout extending ~205 km from ground zero.
Is the B83 bigger than the bomb that hit Hiroshima?
The Hiroshima bomb (Little Boy) had a yield of about 15 kilotons. The B83 at 1.2 Mt is 80× more powerful than the Hiroshima bomb.