The map above simulates a 300-kiloton nuclear airburst over São Paulo, Brazil — roughly the size of a modern deployed warhead. The coloured rings show the estimated fireball, the zones of heavy, moderate and light blast damage, the reach of the thermal flash and the ionizing-radiation dose. Drag the marker or change the weapon in the full simulator to explore other scenarios.
The metropolitan area is home to about 22.6 million people — the rings above are drawn to real scale over their homes.
The marker is on Praça da Sé in the historic centre. The 1.9 km zone of total destruction covers the cathedral, the Pátio do Colégio where the city was founded, the Municipal Theatre and the Anhangabaú valley; the 4.7 km collapse ring reaches Luz station, Liberdade, Bela Vista and the Minhocão elevated road. Third-degree burns extend to about 7.5 km over Paulista Avenue, Higienópolis, Brás, Mooca and the Pacaembu stadium; the 14.5 km ring of broken windows covers Pinheiros, Vila Mariana, Ibirapuera Park, Tatuapé and Santana.
Greater São Paulo has about 22 million inhabitants and its centre is a dense vertical city of apartment towers, which both shield and channel blast in ways the plain circles cannot show. The terrain rolls gently; the Tietê and Pinheiros valleys are too shallow to give real shadow. Brazil renounced nuclear weapons in the 1990s and the continent is a nuclear-weapon-free zone under the Treaty of Tlatelolco, which makes this a textbook exercise rather than a threat picture. The effects article explains each ring.
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