At 11:02 a.m., on 09 August 1945 at an altitude of 1,650 feet, Fat Man exploded over Nagasaki. The yield of the explosion was later estimated at 21 kilotons, 40 percent greater than that of the Hiroshima bomb.
In general, though Fat Man exploded with greater force than Little Boy, the damage at Nagasaki was not as great as it had been at Hiroshima.
The hills of Nagasaki, its geographic layout, and the bomb's detonation over an industrial area all helped shield portions of the city from the weapon's blast, heat, and radiation effects.
The explosion affected a total area of approximately 43 square miles. About 8.5 of those square miles were water, and 33 more square miles were only partially settled.
Many roads and rail lines escaped major damage. In some areas electricity was not knocked out, and fire breaks created over the last several months helped to prevent the spread of fires to the south. ~ read more
