Mount Vesuvius didn't kill everyone. Refugees from Pompeii fled to towns along the nearby coast, where the Roman government seems to have stepped in to provide support. There's evidence that survivors formed Pompeiian communities+ in their new home towns, no doubt passing on to their children and grandchildren tales of that very bad day in Pompeii.

(If you ever visit Pompeii, don't forget the National Archaeological Museum of Naples, where much of what's been dug up there and in Herculaneum has ended up on display—including one memorable room that shows just how obsessed the Romans were with phalluses. Graffiti on the walls ain't the half of it.)