Replies

1 Megaton Surface Blast: Pressure Damage
The fission bomb detonated over Hiroshima had an explosive blast equivalent to 12,500 tons of TNT. A 1 megaton hydrogen bomb, hypothetically detonated on the earth's surface, has about 80 times the blast power of that 1945 explosion.
Radius of destructive circle: 1.7 miles

12 pounds per square inch
At the center lies a crater 200 feet deep and 1000 feet in diameter. The rim of this crater is 1,000 feet wide and is composed of highly radioactive soil and debris. Nothing recognizable remains within about 3,200 feet (0.6 miles) from the center, except, perhaps, the remains of some buildings' foundations. At 1.7 miles, only some of the strongest buildings -- those made of reinforced, poured concrete -- are still standing. Ninety-eight percent of the population in this area are dead.
Radius: 2.7 miles

5 psi
Virtually everything is destroyed between the 12 and 5 psi rings. The walls of typical multi-story buildings, including apartment buildings, have been completely blown out. The bare, structural skeletons of more and more buildings rise above the debris as you approach the 5 psi ring. Single-family residences within this this area have been completely blown away -- only their foundations remain. Fifty percent of the population between the 12 and 5 psi rings are dead. Forty percent are injured.
Radius: 4.7 miles
2 psi

Any single-family residences that have not been completely destroyed are heavily damaged. The windows of office buildings have been blown away, as have some of their walls. The contents of these buildings' upper floors, including the people who were working there, are scattered on the street. A substantial amount of debris clutters the entire area. Five percent of the population between the 5 and 2 psi rings are dead. Forty-five percent are injured.
Radius: 7.4 miles

1 psi
Residences are moderately damaged. Commercial buildings have sustained minimal damage. Twenty-five percent of the population between the 2 and 1 psi rings have been injured, mainly by flying glass and debris. Many others have been injured from thermal radiation -- the heat generated by the blast. The remaining seventy-five percent are unhurt.
NOTE: This information has been drawn mainly from "The Effects of Nuclear War" (Washington: Office of Technology Assessment, Congress of the United States, 1979). The zones of destruction described on this page are broad generalizations and do not take into account factors such as weather and geography of the target.