Atomic weapon blast zones

Print edition : July 18, 1998

THE following summary of blast effects in various zones, measured out from the hypocentre, is from material in the reference library of the High Energy Weapons Archive accessed on the Internet. The details are available for several yields. In deference to those who believe that Pakistan has overstated the yield in its tests, the summary for a yield of 10 kt is presented here.

Zone 1: Vaporisation Point - Region extending up to 0.8 km. Everything is vaporised by the atomic blast. 98 per cent fatalities. Overpressure: 1.76 kg per sq cm. Wind velocity: 510 kmph.

Zone 2: Total Destruction - Region extending up to 1.6 km. All structures above ground are destroyed. 90 per cent fatalities. Overpressure: 1.19 kg per sq cm. Wind velocity: 465 kmph.

Zone 3: Severe Blast Damage - Region extending up to 2.8 km. Factories and other large-scale buildings collapse. Severe damage to highway bridges. Rivers sometimes flow counter-current. 65 per cent fatalities, 30 per cent injured. Overpressure: 0.60 kg per sq cm. Wind velocity: 415 kmph.

Zone 4: Severe Heat Damage - Everything flammable burns. People in the area suffocate due to the fact that most of the available oxygen is consumed by the fires. 50 per cent fatalities, 45 per cent injured. Overpressure: 0.42 kg per sq cm. Wind velocity: 225 kmph.

Zone 5: Severe Fire and Wind Damage - Residence structures are severely damaged. People are blown around. Second- and third-degree burns suffered by most survivors. 15 per cent dead, 50 per cent injured. Overpressure: 0.21 kg per sq cm. Wind velocity: 160 kmph.

In South Asian conditions, a major percentage of the injured, even in Zone 5, are likely to turn into fatalities owing to the non-arrival or late arrival of emergency medical help. Third-degree burn survivors with more than 25 per cent of the body covered by burns would immediately go into shock and would need emergency treatment. The exact number of fatalities obviously depends upon the population density of the area that is hit.

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