Castle Bravo - Detonation

Detonation

The detonation took place at 06:45 on March 1, 1954 local time (18:45 on February 28 GMT).

When Bravo was detonated, it formed a fireball almost four and a half miles (roughly 7 km) across within a second. This fireball was visible on Kwajalein atoll over 250 miles (400 km) away. The explosion left a crater 6,500 feet (2,000 m) in diameter and 250 feet (76 m) in depth. The mushroom cloud reached a height of 47,000 feet (14,000 m) and a diameter of 7 miles (11 km) in about a minute; it then reached a height of 130,000 feet (40 km) and 62 miles (100 km) in diameter in less than 10 minutes and was expanding at more than 100 metres per second (360 km/h; 220 mph). As a result of the blast, the cloud contaminated more than seven thousand square miles of the surrounding Pacific Ocean including some of the surrounding small islands like Rongerik, Rongelap and Utirik.

In terms of TNT tonnage equivalence, Castle Bravo was about 1,000 times more powerful than each of the atomic bombs which were dropped on Hiroshima and Nagasaki during World War II. The largest nuclear explosion ever produced was a test conducted by the Soviet Union seven and a half years later, the ≈50 Mt Tsar Bomba. Castle Bravo is the fifth largest nuclear explosion in history, exceeded by the Soviet tests of Tsar Bomba at 50.6 Mt, Test 219 (24.2 Mt), and two other ~20 Mt Soviet tests in 1962 at Novaya Zemlya.