Methodology

To find how a nuclear detonation could affect the 23 capitals of the G20 nations and those with a nuclear arsenal, 24/7 Wall St. used Nukemap, a site that simulates detonation of nuclear bombs. We have chosen two typical warhead yields, 100 kilotons and 800 kilotons, detonated in the air over the center, or important landmarks in these cities. Countries are ordered alphabetically. Of the three capital cities of South Africa we have chosen Pretoria, the seat of the executive branch.

• Nuclear bombs with 100-kiloton yield detonated in the air at 0.9 miles altitude have a fireball radius of 0.24 miles and a light blast damage radius of 5.7 miles, for a total affected area of 102.3 square miles.
• Nuclear bombs with 800-kiloton yield detonated in the air at 1.8 miles altitude have a fireball radius of 0.55 miles and a light blast damage radius of 11.4 miles, for a total affected area of 409.3 sq. miles.

We also added the average population within the light damage blast range averaged over a 24-hour period. Light damage can be caused by an overpressure – the pressure caused by a shock wave exceeding normal atmospheric pressure – of 1 psi. (Psi is a measure of pressure equaling a pound of force per square inch.) All data is from Nukemap, except for population figures.

Population figures came from the United Nations’ Population Division The World’s Cities in 2018. Each city population is either within the “city proper” (the administrative boundary), “urban agglomeration” area (the contiguous urban area, or built-up area), or “metropolitan area” (the nearby areas with economic and social interconnectedness).