Osaka city centre sits 305.8 km from Iwakuni MCAS, Japan, the most plausible strategic target in the area (high targeting confidence). Modelled strike: 300 kt surface burst.
Estimated survival chance at city centre: 99%
What a strike on Iwakuni MCAS, Japan would mean
A 300 kt detonation produces a fireball 743 m across in radius. Reinforced concrete fails out to 1.8 km (20 psi). Most residential buildings collapse within 3.7 km (5 psi), and windows shatter dangerously out to 8.3 km (1 psi). Anyone in line of sight within 6.9 km suffers third-degree burns from the thermal pulse.
Because military and hardened targets are typically attacked with surface bursts, fallout matters here: with prevailing winds the dangerous plume would stretch roughly 86 km east of ground zero. Osaka city centre lies outside the projected corridor under these wind assumptions.
Most plausible targets near Osaka
| Target | Type | Distance | Assumed yield | Confidence |
|---|---|---|---|---|
| Iwakuni MCAS, Japan | military | 306 km | 300 kt | high |
| Yokota Air Base, Japan | military | 368 km | 300 kt | high |
| Yokosuka Naval Base | military | 385 km | 300 kt | high |
| Tokyo (Kasumigaseki) | government | 401 km | 300 kt | high |
| Haneda, Tokyo | airport | 400 km | 150 kt | medium |
Key blast radii (300 kt surface burst)
| Effect | Radius | What happens |
|---|---|---|
| Fireball | 743 m | Complete vaporisation |
| 20 psi blast | 1.8 km | Hardened structures destroyed, ~100% fatalities |
| 5 psi blast | 3.7 km | Most buildings collapse, widespread fatalities |
| 3rd-degree burns | 6.9 km | Full-thickness burns to exposed skin |
| 500 rem radiation | 2.4 km | Lethal dose without medical care |
| 1 psi blast | 8.3 km | Window breakage, light damage, glass injuries |
How Osaka can prepare
With a population density of 12,000 people/km², Osaka'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.
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