Are you being facetious? How many people do you think would be killed by a nuclear blast of that size? How many more would die in agonizing pain as the fall-out spread over the globe? How many more from horrible cancers forty years from now? A volcanic eruption of that size would destroy agriculture and cause most of Africa, much of Asia, much of South America, and probably good chunks of North America and Europe to starve. It would also send ash contaminated with nuclear fall-out into the atmosphere.