Trinity on Hong Kong
25 kt fission weapon · China · Population 7,500,000 · Density 7,100/km²
About this scenario
This page calculates what would happen if the Trinity (USA, 1945) detonated over Hong Kong (China). First nuclear test.
A special administrative region of China and one of the world's most densely populated territories. With an urban-core density of about 7,100 people per km², even a relatively small detonation over the city center would affect a large population.
The Trinity delivers 25 kt of explosive yield — 2× 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 (Trinity over Hong Kong)
| Effect zone | Radius | Est. affected |
|---|---|---|
| Fireball (vaporization, 100% fatal) | 0.53 km | ~6,159 |
| Severe blast (20 PSI, ~98% fatal) | 1.39 km | ~36,339 |
| Moderate blast (5 PSI, ~50% fatal) | 2.98 km | ~77,330 |
| Light blast (1 PSI, glass injuries) | 8.48 km | ~70,221 |
| 3rd-degree thermal burns | 2.51 km | — |
| 2nd-degree thermal burns | 4.49 km | — |
Estimated total fatalities: ~119,828 · Estimated total affected (inside 1 PSI light-blast radius): ~1,602,448.
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 Trinity struck ground level rather than detonating optimally above Hong Kong.
| Effect zone | Radius (surface burst) |
|---|---|
| Fireball | 0.42 km |
| Severe blast (20 PSI) | 0.77 km |
| Moderate blast (5 PSI) | 1.64 km |
| Light blast (1 PSI) | 4.66 km |
| 3rd-degree thermal burns | 1.50 km |
| Lethal fallout zone | ~43.5 km |
Run this scenario in the simulator
See the actual blast zones overlaid on a map of Hong Kong with population-density-based casualty estimates updated in real time as you move the detonation point.
🎯 Open this scenario on the mapTrinity on other cities
Other weapons on Hong Kong
FAQ
What would happen if the Trinity detonated over Hong Kong?
In an air burst over Hong Kong, the Trinity (25 kt) would produce a fireball about 0.53 km in radius. The 5 PSI moderate-blast zone — where most residential buildings collapse — would extend to 2.98 km. Light blast damage and shattered windows would reach 8.48 km. Given Hong Kong's urban density (~7,100/km²), this scenario yields an estimated 119,828 immediate fatalities and about 70,221 additional injured.
How many people would die in Hong Kong from a Trinity strike?
An air burst of the Trinity over Hong Kong could cause an estimated 119,828 immediate fatalities and 70,221 additional injuries. The fireball alone (radius 0.53 km) would kill approximately 6,159 people; the severe-blast zone (20 PSI, radius 1.39 km) would add 36,339; the moderate-blast zone (5 PSI, radius 2.98 km) would add 77,330 more. Real numbers depend heavily on time of day, sheltering, weather, and altitude of detonation.
What is the blast radius of the Trinity on Hong Kong?
For an air burst over Hong Kong: fireball 0.53 km, severe blast (20 PSI) 1.39 km, moderate blast (5 PSI) 2.98 km, light blast (1 PSI) 8.48 km. Thermal radiation causes 3rd-degree burns out to 2.51 km. A surface burst would shrink the blast radii by roughly 40 percent but generate massive radioactive fallout extending ~43 km from ground zero.
Is the Trinity bigger than the bomb that hit Hiroshima?
The Hiroshima bomb (Little Boy) had a yield of about 15 kilotons. The Trinity at 25 kt is 2× more powerful than the Hiroshima bomb.