I think you over-estimate the power of nuclear weapons. It would take something with the power of an asteroid larger than 1km in order to cause any sort of geological damage to the earth. Nuclear weapons don't have nearly that much power. It might leave a small local crater, but there's no way you'd see much of an increase in volcanic activity or earthquakes. The main harm would be in the dust and debris it would kick up into the atmosphere, not to mention the radiation. The geological damage resulting from a nuclear war would be minimal. The only reason we get volcanoes and earthquakes is because they're found along fault lines near where two or more tectonic plates rub together. There are virtually no geological events anywhere else. And a nuclear bomb certainly doesn't have enough power to cause a crack to appear in the earth's crust.



They're also much less powerful than what we have in reality. Fallout's bombs are the same as the Fatman type that was dropped on Hiroshima and Nagasaki. Those don't have nearly the yield of the ones we have today. Other than the usual blast damage, dropping a bunch in one area wouldn't cause that much damage to the geology of the area.



No, because we'd probably go through another Ice Age before any sort of Global Warming kicked in.