W88 on San Francisco
475 kt thermonuclear weapon · USA · Population 873,000 · Density 7,300/km²
About this scenario
This page calculates what would happen if the W88 (USA, 1988) detonated over San Francisco (USA). Modern SLBM warhead.
The financial and technology capital of the western United States, on a dense 121 km² peninsula. With an urban-core density of about 7,300 people per km², even a relatively small detonation over the city center would affect a large population.
The W88 delivers 475 kt of explosive yield — 32× 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 (W88 over San Francisco)
| Effect zone | Radius | Est. affected |
|---|---|---|
| Fireball (vaporization, 100% fatal) | 1.71 km | ~66,767 |
| Severe blast (20 PSI, ~98% fatal) | 3.68 km | ~238,311 |
| Moderate blast (5 PSI, ~50% fatal) | 7.87 km | ~555,128 |
| Light blast (1 PSI, glass injuries) | 22.40 km | ~504,091 |
| 3rd-degree thermal burns | 8.39 km | — |
| 2nd-degree thermal burns | 15.02 km | — |
Estimated total fatalities: ~860,206 · Estimated total affected (inside 1 PSI light-blast radius): ~11,503,388.
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 W88 struck ground level rather than detonating optimally above San Francisco.
| Effect zone | Radius (surface burst) |
|---|---|
| Fireball | 1.37 km |
| Severe blast (20 PSI) | 2.03 km |
| Moderate blast (5 PSI) | 4.33 km |
| Light blast (1 PSI) | 12.32 km |
| 3rd-degree thermal burns | 5.03 km |
| Lethal fallout zone | ~141.2 km |
Run this scenario in the simulator
See the actual blast zones overlaid on a map of San Francisco with population-density-based casualty estimates updated in real time as you move the detonation point.
🎯 Open this scenario on the mapW88 on other cities
Other weapons on San Francisco
FAQ
What would happen if the W88 detonated over San Francisco?
In an air burst over San Francisco, the W88 (475 kt) would produce a fireball about 1.71 km in radius. The 5 PSI moderate-blast zone — where most residential buildings collapse — would extend to 7.87 km. Light blast damage and shattered windows would reach 22.40 km. Given San Francisco's urban density (~7,300/km²), this scenario yields an estimated 860,206 immediate fatalities and about 504,091 additional injured.
How many people would die in San Francisco from a W88 strike?
An air burst of the W88 over San Francisco could cause an estimated 860,206 immediate fatalities and 504,091 additional injuries. The fireball alone (radius 1.71 km) would kill approximately 66,767 people; the severe-blast zone (20 PSI, radius 3.68 km) would add 238,311; the moderate-blast zone (5 PSI, radius 7.87 km) would add 555,128 more. Real numbers depend heavily on time of day, sheltering, weather, and altitude of detonation.
What is the blast radius of the W88 on San Francisco?
For an air burst over San Francisco: fireball 1.71 km, severe blast (20 PSI) 3.68 km, moderate blast (5 PSI) 7.87 km, light blast (1 PSI) 22.40 km. Thermal radiation causes 3rd-degree burns out to 8.39 km. A surface burst would shrink the blast radii by roughly 40 percent but generate massive radioactive fallout extending ~141 km from ground zero.
Is the W88 bigger than the bomb that hit Hiroshima?
The Hiroshima bomb (Little Boy) had a yield of about 15 kilotons. The W88 at 475 kt is 32× more powerful than the Hiroshima bomb.