The damage was amplified by the composite effect of the heat rays, blast and radioactivity. It is estimated that a total of 350,000 civilians and military personnel suffered from the direct effects of bombing. We have no way to estimate the precise extent of the damage, but it is thought that around 140,000 people died by the end of 1945 alone. All buildings were completely destroyed within a radius of two kilometers from the hypocenter.
(1) Damage by the Heat Rays
At the moment of the atomic explosion, the fireball created reached a diameter of more than 280 meters in the space of one second. The temperature on its surface reached 5,000 degrees Celsius.
Damage to the Human Body from the Heat Rays
People close to the center say that the atomic explosion looked yellowish red, those farther away reported a bright bluish-white light resembling burning magnesium. The severe heat rays from the explosion cause burns to people in a radius of up to 3.5 kilometers. Those within 1.2 kilometers of the hypocenter sustained fatal injuries to their internal organs and many died in the next few days.
Nails and Skin Left by a Junior High Student
Noriaki Teshima, a first-year student at Second Hiroshima Prefectural Junior High School, was exposed while engaged in building demolition. Burned so severely that skin hung loose from his whole body, he was rescued and taken home by a friend. Unable to bear his thirst, he reportedly sucked the pus from the ends of his fingers, from which the nails had peeled off. He died in agony on the next day, August 7. His mother kept his fingernails and some of his skin as a remembrance to show his father, who had been sent off to war.
Damage to Materials from the Heat Rays
Even in the area 600 meters from the hypocenter, the temperature of the heat rays reached 2,000 degrees Celsius. Clothing and Indian-inked letters written on papers that were located far from the explosion spot were instantly burned. Wooden fences along the railway naturally ignited and burned, too.
Round Roof Tile
Roof tile surfaces within 600 meters of the hypocenter melted, becoming rough and bubbly where they were exposed to direct heat rays.
A Human Shadow on the Steps (the segment of stone steps of the bank)
A human shadow was imprinted on the steps at the entrance to the Sumitomo Bank at Kamiya-cho, 250 meters from the hypocenter. This person must have been sitting on the step, looking toward the hypocenter and died on the place after being completely burned. The place where the person had been sitting remained dark, while the surrounding surface of the stone steps turned white due to the heat rays.