How Nuclear Bombs Kill and Destroy At the moment of explosion, the atomic bomb released its destructive power in three forms: radiation (15%), heat rays (35%) and blast pressure (50%). The radiation was composed of neutrons and gamma rays, which measured 604 rad and 3,500 rad respectively at 500 meters (0.3 miles) from ground zero, where no one survived. Low level radiation from fallout and secondary sources would cause delayed effects in later days. Heat rays measured at 3.5 kilometers (2.2 miles) from ground zero were 1.8 kcal/cm2. The exposed body parts of people outside buildings suffered 1st-4th degree burns. The heat caused buildings to burst into flames. Fire quickly spread and engulfed the entire city. The blast pressure was 28 meters (0.01 miles)/second at the point 3.2 kilometers (2 miles) from ground zero with an estimated speed of 280 meters (0.2 miles)/second at the blast center. Houses within 5-kilometer (3-mile) radius were destroyed. Damage from shock waves was felt as far as 60 kilometers (37 miles) away. A 1976 analysis revealed the estimated height to be 503±10m (Kerr & Solomon). Kerr GD, Solomon DL: The epicenter of the Nagasaki weapon—A reanalysis of available data with recommended values. ORNL-TM-5139 (1976). Epilation caused by radiation. Burn victim. This photograph was taken after the transplantation of skin grafts. This wooden house collapsed as a result of the blast, near Danbara, 3 kilometers (about 1.9 miles) from ground zero. The photographs above are from the film, Effects of the Atomic Bomb on Hiroshima and Nagasaki shot by Nihon Eigasha, Ltd. in September 1945. Hypocenter 1.0 0 503 Altitude (m) 2.0 3.0 4.0 Distance (km) Radiation γ rays 319.5 78.5 7.83 0.89 0.13 0.02 21.1 3.31 0.14 0.006 0 Radiation dose Neutron rays Hypocenter 1.0 0 503 Altitude (m) 2.0 3.0 4.0 Distance (km) Heat Rays 229.4 42.2 11.0 4.4 2.2 Heat level (cal/cm2) Physical phenomena Hypocenter 1.0 0 503 Altitude (m) 2.0 3.0 4.0 Distance (km) Blast Wind Burning of white paper Burning of black paper Melting of tiles 440 160 60 30 Blast Wind (m/sec) Physical phenomena Complete destruction of wooden houses Partial destruction of walls, ceilings, etc (wooden houses) Serious damage to ferroconcrete buildings