Nuclear weapon effects
Surface Burst
A nuclear detonation at ground level, producing roughly 40-50% smaller blast radius than an air burst but creating massive radioactive fallout.
A surface burst is used when the target is hardened (silos, command bunkers) or when the attacker wants to maximize fallout. The fireball touches the ground, vaporizing soil and creating a large crater. Roughly half the bomb energy goes into the crater and ground shock instead of blast and thermal effects. The radioactive plume can render hundreds of square kilometers uninhabitable for years.
Related terms
Air Burst
A nuclear detonation above the ground at optimal altitude, maximizing the area affected by blast and thermal radiation while producing minimal fallout.
Fallout
Radioactive material thrown into the atmosphere by a surface-burst nuclear detonation, which then settles back to earth over hours to weeks.