The map above simulates a 300-kiloton nuclear airburst over London, UK — 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 9.6 million people — the rings above are drawn to real scale over their homes.
The marker is on Charing Cross. The 1.9 km zone of total destruction covers Trafalgar Square, Whitehall, Downing Street, Covent Garden, Soho and Waterloo station; the 4.7 km collapse ring reaches Parliament, Buckingham Palace, the City's western half, King's Cross, the South Bank and Hyde Park Corner. Third-degree burns extend to about 7.5 km over the whole City and Tower Bridge, Islington, Kensington, Elephant and Castle and Regent's Park; the 14.5 km ring of broken windows reaches Canary Wharf, Hampstead, Brixton, Hammersmith and Hackney.
About 6 million people live inside the outer ring, in the densest part of a city of 9 million. London is flat along the Thames and the river is narrow, so terrain gives no protection. The UK keeps about 225 warheads, all on Trident submarines, and the Cold War planning assumption was that London would receive several weapons of this size. The 800-kiloton Topol scenario over the same point shows the next step up.
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