What this is
Companion tool to the game "Robot vs Drone vs Human". The game drills knowledge into your body; this shows real numbers on the real map.
Everything runs on free public data: GSI Japan map tiles, elevation API (1 m LiDAR), designated evacuation sites and 1945β50 US aerial photos; the Hazard Map Portal's flood, tsunami, storm-surge and landslide layers; Open-Meteo wind; JMA earthquake feed. No API keys, no accounts β if this server dies, the page still works as long as the sources do.
Your location is used on-device only when you press "My position" and is never sent anywhere. Elevation and wind lookups send the tapped coordinates to GSI and Open-Meteo, nowhere else.
Sources and limits
- The nuclear estimate uses scaling laws from Glasstone & Dolan, The Effects of Nuclear Weapons, for an airburst; surface bursts, terrain and weather change it greatly. The fallout wedge uses current surface wind; real fallout follows upper winds and shifts over time. Do not base evacuation decisions on it.
- Designated evacuation sites are for natural disasters. Missile-grade emergency shelters (underground stations, malls) are a separate list per prefecture on the Civil Protection Portal. Tokyo is already on this map (5,163 entries from the Tokyo Metropolitan list, geocoded with GSI, 99% matched).
- The 1945β50 aerial photos cover urban areas only. Post-war redevelopment changed terrain and buildings; treat surviving districts as hints, not rules.
- Hazard legends follow the Hazard Map Portal.
- This tool does not replace official instructions. In an emergency, J-Alert, your municipality and NHK come first.