It's very likely that they didn't really know that Vesuvio was a volcano at all... According to various sources they just consider it a mountain, given that it

It's very likely that they didn't really know that Vesuvio was a volcano at all... According to various sources they just consider it a mountain, given that it was all covered of vegetation and there was no recorded trace of activity in the previous centuries. Plus, as said... Growing stuff there is a pleasure (reason why plenty of people still live in that area). Have you ever tasted the tomatoes growing there? There's a reason why the pizza you can have nearby is something you can't eat anywhere else in the world!