Ivy Mike on Los Angeles
10.4 Mt thermonuclear weapon · USA · Population 3,898,747 · Density 3,200/km²
About this scenario
This page calculates what would happen if the Ivy Mike (USA, 1952) detonated over Los Angeles (USA). First hydrogen bomb test.
The second-most populous US city, sprawling across Southern California with a metro area of nearly 13 million. With an urban-core density of about 3,200 people per km², even a relatively small detonation over the city center would affect a large population.
The Ivy Mike delivers 10.4 Mt of explosive yield — 693× 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 (Ivy Mike over Los Angeles)
| Effect zone | Radius | Est. affected |
|---|---|---|
| Fireball (vaporization, 100% fatal) | 5.86 km | ~345,671 |
| Severe blast (20 PSI, ~98% fatal) | 10.20 km | ~679,655 |
| Moderate blast (5 PSI, ~50% fatal) | 21.80 km | ~1,865,710 |
| Light blast (1 PSI, glass injuries) | 62.01 km | ~1,694,184 |
| 3rd-degree thermal burns | 29.72 km | — |
| 2nd-degree thermal burns | 53.23 km | — |
Estimated total fatalities: ~2,891,036 · Estimated total affected (inside 1 PSI light-blast radius): ~38,661,357.
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 Ivy Mike struck ground level rather than detonating optimally above Los Angeles.
| Effect zone | Radius (surface burst) |
|---|---|
| Fireball | 4.69 km |
| Severe blast (20 PSI) | 5.61 km |
| Moderate blast (5 PSI) | 11.99 km |
| Light blast (1 PSI) | 34.11 km |
| 3rd-degree thermal burns | 17.83 km |
| Lethal fallout zone | ~485.3 km |
Run this scenario in the simulator
See the actual blast zones overlaid on a map of Los Angeles with population-density-based casualty estimates updated in real time as you move the detonation point.
🎯 Open this scenario on the mapIvy Mike on other cities
Other weapons on Los Angeles
FAQ
What would happen if the Ivy Mike detonated over Los Angeles?
In an air burst over Los Angeles, the Ivy Mike (10.4 Mt) would produce a fireball about 5.86 km in radius. The 5 PSI moderate-blast zone — where most residential buildings collapse — would extend to 21.80 km. Light blast damage and shattered windows would reach 62.01 km. Given Los Angeles's urban density (~3,200/km²), this scenario yields an estimated 2,891,036 immediate fatalities and about 1,694,184 additional injured.
How many people would die in Los Angeles from a Ivy Mike strike?
An air burst of the Ivy Mike over Los Angeles could cause an estimated 2,891,036 immediate fatalities and 1,694,184 additional injuries. The fireball alone (radius 5.86 km) would kill approximately 345,671 people; the severe-blast zone (20 PSI, radius 10.20 km) would add 679,655; the moderate-blast zone (5 PSI, radius 21.80 km) would add 1,865,710 more. Real numbers depend heavily on time of day, sheltering, weather, and altitude of detonation.
What is the blast radius of the Ivy Mike on Los Angeles?
For an air burst over Los Angeles: fireball 5.86 km, severe blast (20 PSI) 10.20 km, moderate blast (5 PSI) 21.80 km, light blast (1 PSI) 62.01 km. Thermal radiation causes 3rd-degree burns out to 29.72 km. A surface burst would shrink the blast radii by roughly 40 percent but generate massive radioactive fallout extending ~485 km from ground zero.
Is the Ivy Mike bigger than the bomb that hit Hiroshima?
The Hiroshima bomb (Little Boy) had a yield of about 15 kilotons. The Ivy Mike at 10.4 Mt is 693× more powerful than the Hiroshima bomb.