The area surrounding the site of the explosion would receive severe damage from tremendous heat, blast, and shock waves. This area would also be severely irradiated. The size of the area receiving severe damage would depend on the size of the exploded weapon. Fallout formation Any effects in outlying areas would be from radioactive fallout.
Fallout is created when a nuclear weapon explodes on or near the ground.
Large amounts of pulverized dirt and rock are sucked up into the rising fireball. The intense heat in the fireball fuses residual radioactive atoms to this debris, which becomes radioactive. The radioactive particles are heavier than air, and settle to earth soon after they are formed. Fallout, transported by the wind, can settle over and area extending hundreds of miles from the point of explosion. Weather conditions, the speed and direction of winds, and the topography of the land would affect the distribution of fallout.