As surveyors collected data from both atomic bomb sites, it was soon clear that the Nagasaki bomb had packed a bigger punch. Fat Man’s yield was about 30 percent greater than Little Boy’s, and the bowl-shaped topography of the Urakami Valley had amplified the force of the explosion. The second bomb had done considerably more damage to comparable structures at a comparable distance from the hypocenter.58 As in Hiroshima, precise casualty figures were hard to pin down. It is believed that 40,000 to 75,000 residents of Nagasaki were killed on August 9 or shortly thereafter, with another 70,000
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