What is the destructive power of today's nuclear weapons?
An average size nuclear weapon would immediately kill everything within a radius of several square miles. The radiation exposure would continue to injure and kill people over a longer period of time and over a greater area. The area of radiation exposure would depend upon prevailing winds, and could spread across continents and beyond. Nuclear weapons in the arsenals of the major nuclear weapons states today have on average a destructive force equal to 25 to 40 times the power of the weapons that destroyed Hiroshima and Nagasaki. Some nuclear weapons have even greater destructive force.
If you want some morbid fun you can go to the Nuclear Weapon Effects Calculator and play around a bit
