San Francisco city centre sits 40.1 km from San Francisco / Silicon Valley, the most plausible strategic target in the area (high targeting confidence). Modelled strike: 455 kt airburst.
Estimated survival chance at city centre: 99% · Estimated metro fatalities: 388.4K, injuries: 467.7K
What a strike on San Francisco / Silicon Valley would mean
A 455 kt detonation produces a fireball 763 m across in radius. Reinforced concrete fails out to 2.6 km (20 psi). Most residential buildings collapse within 5.3 km (5 psi), and windows shatter dangerously out to 11.9 km (1 psi). Anyone in line of sight within 8.2 km suffers third-degree burns from the thermal pulse.
An airburst maximises blast damage but produces minimal local fallout, so for San Francisco the dominant risks are blast and thermal effects rather than radiation.
Most plausible targets near San Francisco
| Target | Type | Distance | Assumed yield | Confidence |
|---|---|---|---|---|
| San Francisco / Silicon Valley | city | 40 km | 455 kt | high |
| Vandenberg SFB | military | 376 km | 300 kt | high |
| Diablo Canyon nuclear plant | energy | 317 km | 100 kt | low |
| Port of LA / Long Beach | port | 586 km | 300 kt | high |
| One Wilshire, Los Angeles | communication | 559 km | 100 kt | low |
Key blast radii (455 kt airburst)
| Effect | Radius | What happens |
|---|---|---|
| Fireball | 763 m | Complete vaporisation |
| 20 psi blast | 2.6 km | Hardened structures destroyed, ~100% fatalities |
| 5 psi blast | 5.3 km | Most buildings collapse, widespread fatalities |
| 3rd-degree burns | 8.2 km | Full-thickness burns to exposed skin |
| 500 rem radiation | 2.6 km | Lethal dose without medical care |
| 1 psi blast | 11.9 km | Window breakage, light damage, glass injuries |
How San Francisco can prepare
With a population density of 7,200 people/km², San Francisco's outcome would hinge on the first hour. The guidance is identical everywhere: get inside, stay inside, stay tuned. A basement or the core of a large concrete building cuts fallout exposure by a factor of 10 or more, and radiation decays fast — dose rates fall ~90% within the first 7 hours and ~99% within two days.
Check your exact address in San Francisco →