View of Vesuvius through the gate at Palestra Samnitica, in Pompeii. What is worth emphasizing, the mountain was not as visible as it is now. The inhabitants of Pompeii and the Herculaneum painted frescoes with Vesuvius, although they did not know how much of a threat this mountain had to them1.
In antiquity, all that was visible was the broad and jagged base of the crater. As Alberto Angela describes it, it had the shape of an ashtray with irregular edges, with one side lower than the rest. Something like the present Colosseum. The people of Pompeii looked at the mountain from the southeast, so they were on the lower part of the volcano. So there was no natural barrier to stop the burning avalanches of ash and gases that would then in 79 CE fell on the city.
Thus, the shape and appearance of the mountain could not suggest to the inhabitants that they were living on a “ticking bomb”. The only real signals that troubled the inhabitants of the region were the constant earthquakes caused by the pressing and accumulating lava underground. For this reason, a large number of people left the towns and villas in the region, thanks to which the number of victims of the blast was not so great.