Gerboise Bleue
France · 1960 · 70 kilotons · pure fission
Overview
First French nuclear test.
With a yield of 70 kilotons[1], the Gerboise Bleue is 4.7× more powerful than the Hiroshima bomb. As a pure fission weapon, it derives its energy from nuclear fission of uranium or plutonium. [2]
Gerboise Bleue Blast Effects
The table below shows the calculated radius of each effect zone for an air burst at optimum height. Values are scaling laws from The Effects of Nuclear Weapons (Glasstone & Dolan, 1977) and the published effects scaling table[3, 4].
| Effect zone | Radius (air burst) |
|---|---|
| Fireball radius | 0.33 km |
| Severe blast (20 psi) | 0.94 km |
| Moderate blast (5 psi) | 2.57 km |
| Light blast (1 psi) | 7.09 km |
| 3rd-degree thermal burns | 4.13 km |
| 2nd-degree thermal burns | 5.25 km |
| 1st-degree thermal burns | 6.81 km |
All radii assume an air burst at optimum height and are 1-D ground-distance estimates from the detonation point. Real-world effects depend on terrain, weather, and building construction. Casualty and fallout estimates are not shown pending a verified population and fallout model.
Run the Gerboise Bleue on a City
Use the interactive simulator to detonate the Gerboise Bleue on any city worldwide. Click any location on the map to see the fireball, blast, and thermal radii (air burst at optimum height) overlaid on real geography.
🎯 Simulate Gerboise BleueRelated Weapons
FAQ
How big is the Gerboise Bleue blast radius?
In an air burst at optimum height, the Gerboise Bleue produces a fireball roughly 0.33 km in radius and a 5 psi moderate-blast zone of about 2.57 km — the area in which most residential buildings would collapse. The 1 psi light-damage radius extends to roughly 7.09 km, where windows shatter.
What is the yield of the Gerboise Bleue?
The Gerboise Bleue has a yield of 70 kilotons of TNT equivalent. That is 4.7× more powerful than the Hiroshima bomb.
Is the Gerboise Bleue bigger than the Hiroshima bomb?
The Hiroshima bomb (Little Boy) had a yield of approximately 15 kilotons. The Gerboise Bleue at 70 kilotons is 4.7× more powerful than the Hiroshima bomb.[5]
What thermal burn radius does the Gerboise Bleue produce?
In an air burst at optimum height, thermal radiation from the Gerboise Bleue can cause 3rd-degree burns out to roughly 4.13 km, 2nd-degree burns to 5.25 km, and 1st-degree burns to 6.81 km.
Sources
- 1.Source: Wikipedia, Gerboise Bleue (nuclear test) — retrieved Oct 2026
- 2.Source: US DoD & ERDA (Glasstone & Dolan), via Atomic Archive, The Effects of Nuclear Weapons, 3rd ed. (1977), Chapter 1 — retrieved Oct 2026
- 3.Source: U.S. DoD / DOE (Glasstone & Dolan, via Atomic Archive), The Effects of Nuclear Weapons, 3rd ed. (1977) §2.127 — retrieved Oct 2026
- 4.Source: Wikipedia, Effects of nuclear explosions — scaling-law table — retrieved Oct 2026
- 5.Source: US DOE / NNSA Nevada Field Office, United States Nuclear Tests, July 1945 through September 1992 (DOE/NV-209 Rev. 16, Sep 2015), NNSS publication library — retrieved Oct 2026