#strabone

«Tali le caratteristiche dell’Italia.Dopo esserci soffermati su molte di cose vorremmo ora attirare l’attenzione sulle più importanti, grazie alle quali i Romani hanno raggiunto una così grande potenza.La prima è che l’Italia si può considerare quasi un’isola ben protetta intorno dai mari ad eccezione di poche parti che sono comunque anch’esse difese dai monti, difficilmente valicabili.La seconda…

There are two theories about the original shape of Mt.Vesuvius and how it changed during time. In both theories, Vesuvius is describled to starting out as classic, symmetric stratovolcano.

In prehistoric times, above, is how the Bay of Naples may have appeared. Mt Vesuvius is the youngest volcano of the Campanian volcanic province, with an age of 30k years old. Vesuvius is a rather tiny volcano. It’s original size might have been not more than 2000 meters. However, in proportions it tends to have large craters. It is also one of those volcanoes that tend to form lava lakes. The volcano I used as example is Mt.Fuji, a just 10k years old volcano

There is a theory that describbe Vesuvius having always been a Caldera (except in it’s early days). But this would make Vesuvius a lazy volcano, while, after 79 AD Eruption, Vesuvius was describled as a restless volcano. It is true that Vesuvius is rather violent and it tends to destroy itself, but once it was a much calmer volcano, with low intensity Strombolian eruptions on average. Those kind of eruption allow a volcano to rebuild itself.

Of course a theory like this would support a weakling volcano. But is not believable that a volcano only has few Plinian eruption here and there, and suddenly, after AD 79, it gets lively, erupting almost nonstop, showing lava fountains as tall as 3 km, having vulcanian eruptions on average and forming lava lakes.

Below another reconstruction (From ‘IL VESUVIO’), I think is more believable (It tells the hystory only from Mercato Eruption).

Vesuvio volcano in prehistoric time. It is a central edifice, with mixed activity. The cone of the volcano is truncated by a large caldera.

The whole volcanic activity built up a new composite cone, inside the caldera.

At this time, Vesuvius would have looked like Mount Tyatya, a Russian-Japanese Volcano in Kuril Islands.

How the Bay of Naples might have looked some years after Mercato.

In 800 B.C. the cone was 3000 m high.

3000 meters is an exaggeration. Vesuvius would have looked like those chimney shaped volcanoes from cartoons, and that is impossible in real life. However, is possible that Vesuvius went back to it’s Fuji-self, and that it was close to be 2000 meters tall.

In 800 B.C. an eruptive phase destroyed a part of the cone. A new caldera has originated.

This is when the massive Avellino occured. The eruption was climatic. The effect were short time. Volcanoes don’t always get severely damaged after a strong eruption, as Fuji and St. Maria shows. Vesuvius survived well to Avellino eruption. The shape we got is close to the ones portrayed in Pompeii Frescos

The barely visible top of Mt.Vesuvius. It seems that there was a V shaped fracture on the top of the mountain, visible from Pompeii. Today Vesuvius crater seems to getting another V-shaped fracture toward Naples. The mountain is squished, but if you enlarge it over the current Vesuvius (photographed from Pompeii), it matches perfectly.

Though the eruption is toned down, the shape is believable.

Strabone (he saw Vesuvius before AD 79) describle Vesuvius this way:

Above these places rises Mount Vesuvius, entirely occupied all around, except at the summit, by beautiful fields. The summit itself is largely flat, but completely sterile, with a cinerary appearance: it shows cavities with fissures that open on sooty rocks on the surface as if they had been devoured by fire. Thus one could suppose that this place previously burned and had craters of fire that then became extinct, once the burning matter had failed. Perhaps this is also the reason for the fertility of the surrounding land as it happens in Catania, where they say that the surface covered by the ash thrown out by the fire of Etna made the earth particularly favorable to the cultivation of the vine. The soil is rich in fact of fatty substance and of burnt earth, which is also capable of producing fruit. Therefore, when the earth is overflowing with fat, it is suitable to catch fire, like any sulfur substance, and after it has dried up and turned off, turned into ashes, it becomes suitable for production. 

And

Vesuvius is a mountain covered with fertile land which seems to have cut the summit horizontally; This upper part forms an almost flat plain, totally sterile, of the color of ashes, in which caves full of fissures, formed of blackened stones as if they had undergone the action of fire, that it may be surmised that there had been a volcano which had gone out after having consumed all the flammable matter that served it as food. Perhaps this is the cause to which we must attribute the marvelous fertility of the mountain slopes.

(Translated with Google, as I only find this text in Italian)  

The volcano was inactive for e long time. In 79 A.D. a new phase of activity began with a new, violent explosion .A new large caldera was created. This edifice is called Monte Somma.

If you look at the current Vesuvius from the top, you’lll notice that the lower part of the caldera (almost 3,5 x 5 km of diameters) points exactly toward Herculaneum, the city that was covered by 22 meters of ash.

The rest is history, and is easy to find materials of Vesuvius Eruption from AD 79 to modern times. There are also several portraits of various eruptions from Vesuvius, since art became more and more accessible.

We can easily find pictures starting from 1631. After Pompeii, Vesuvius quickly grew up a Gran Cono. By 1500 it looked about like how it looks today. 

1631 eruption destroyed the Gran Cono. It regrew back, as we can see today