HC Deb 08 August 1980 vol 990 cc480-1W
Mr. Haynes

asked the Secretary of State for Defence (1) what is the circumference and depth of the crater caused by a 10-megaton bomb at ground level;

(2) what is the extent of the main fire zone caused by the heat flash of a 10-megaton bomb at ground level;

(3) what would be the effect in terms of fire and blast on population and property if a 10-megaton bomb were exploded at ground level in a built-up area.

Mr. Pym

For representative geology and typical atmospheric conditions, it is estimated that a 10-megaton explosion at ground level would produce a crater approximately 1,800 feet in diameter and 400 ft deep. Reinforced concrete structures would be levelled out to a radius of about two and a half miles and factories and commercial buildings would collapse out to a radius of about four miles. Two-storey brick houses would be destroyed out to a radius of six miles and severely damaged out to a radius of about eight miles.

Injuries to people from flying glass and debris could be expected at distances of 15 miles and burn injuries to persons exposed in the open would occur at distances of up to 22 miles. Fires would be started by ignition of paper and similar materials out to a distance of approximately 20 miles.