Board Thread:Questions and Answers/@comment-6104247-20130430210408/@comment-201.215.61.190-20130504232249

The problem is not the ash, but all what stays up on the atmosphere for some time (up to some years). Tambora's eruption on 1816 was "just" a VEI 7, and you are thinking about VEI 8 eruptions, so: they may make ash fall a thousand kms around the crater, although just on half that range would be really problematic, it mostly depends on the climate and such things in the region that surrounds the volcano; but if you think about long lasting effects, well, search what happened with Tambora, and make it way worse, :P

@Local Mafia Boss: Vesubio may be a somewhat large volcano, whose danger lays more over the population density around it than anything else, but the calderas around it are what he might be talking about: Campi Flegrei and other 2 ones that are around, or make, the bay of Naples, and there are some more calderas around the zone, up to the south of Rome if I'm not mistaken. Anyway, i don''t know if those ones erupting would have severe impact on the world, directly, as economically, they would devastate at least a highly populated chunk of a country in the middle of Europe.

Large calderas that may or may not be active: Yellowstone, Taupo (Northern Island, New Zealand..., it throws at least VEI 6-7 with regularity), there is something somewhere on southwest Bolivia that seems big, and well, just search for them, they are everywhere, :P