• 1) At Herculaneum (Ercolano). The city was destroyed by the eruption of 79 A.D., whose products are exposed on the southern wall of the excavations. Before the eruption, the city was situated on a small promontory directly above a beach. This beach is now exposed in the lowest part of the excavations and is currently 4 metres below sea-level. The subsidence of the ancient sea line has been produced by deflation of the volcano after large eruptions. The present retreat of sea coast (250 m) has been caused by the accumulation of volcanic deposits erupted after 79 A.D..We have here an example of the contrasting actions of volcanoes which both cause subsidence of the crust and formation of new land by the emission of material.

 

 

The stratigraphy of the deposits has been studied in detail by Haraldur Sigurdsson and co-workers in 1985. The figure shows the different flow-units identified by these authors. The basal pumice-fall deposits are not found in this area, but they are visible at Oplonti and Pompei. Indeed, the overall thickness of the pyroclastic deposits exposed here is mostly due to pyroclastic flow units. The first deposit shown immediately above the ancient coast is an ash layer interpreted as a surge. It is 20-40 cm thick. The majority of the skeletons found in this area lie within this deposit. Above this layer is a massive deposit of a pyroclastic flow containing carbonized wood and fragments of tiles. The thickness of this deposit is less than 1.5 m. Above this layer are several alternating surge and pyroclastic flow layers. In many houses there is abundant evidence of processes of carbonization of wood due to the high temperature of the deposit. According to some authors (Mike Sheridan, for example) the topmost layers are related to mudflows.

These flow units have been correlated with similar deposits in other places around Vesuvius. If this correlation is correct, the timing of the destruction would be several hours after the beginning of the eruption, since the first phase was characterized mostly by a pumice-fall. It must be recalled that Pliny the Elder was not allowed to disembark in Herculaneum, on his arrival with the Roman fleet, because of the "ruin of the mountain", so that he was compelled to disembark in Stabiae to the south-east, from where he was not able to escape because of the opposing winds from the north-west (see Pliny route and Misenum were was stationed the roman fleet).

• 3) In Torre Annunziata you may visit the Oplonti Villa, once the country-villa of a wealthy family, where the products of the early phases of the eruption are exposed. The first pumice-fall probably produced some partial collapse of roofs under the load and a partial burning of the buildings. The arrival of more energetic flows cut away the top part of the buildings above the pumice deposits. In the yard of the villa the roots of the trees destroyed by the eruption are visible.
• 3) At Pompei from the Forum it is possible to see the Vesuvius (8 km far away). Many houses, shops, thermal baths gave an hint of the life at the time of the roman empire, but nothing is more breathtaking of people and animals petrified in their last moments before being killed by the arrival of pyroclastic surges and flows. Contrary to the common belief, many people were killed not by gas, but by hot surges and pyroclastic flow. These phenomena occurred sometime after the beginning of the eruption as testified by the findings of people above the early pumice fall.
• 3bis) Before climbing onto Vesuvius you may visit the wonderful "Villa Regina" at Boscoreale (follow the directions from the exit of the Autostrada at Pompei or ask local people how to reach it). This villa was a country ranch (villa rustica) with production of grapes for the local wine "Falernum". Here you can see the entire sequence of the products of the eruption as well as a small nice museum with the items found in the villa.
• 4) On the way to Vesuvius, on the "Autostrada" from Torre Annunziata to Torre del Greco, you can see on the right the small hill of Camaldoli della Torre, with a monastery on the top, which is a scoria cone of a lateral eruption. Leave the "autostrada" at Torre del Greco and start to observe the lava flows of the historical eruptions of Vesuvius. Torre del Greco has been destroyed several times, in 1631, 1737, 1794, 1861. Every time the city has been rebuilt in the same place, because of the richness of the soils and the abundance of crops. Along the road it is possible to see the lava structures of the 1858 eruption, which lasted for two years. The products of the 79 A.D. eruption are shown at the junction of the road to the Vesuvius Observatory. The lava flow of 1944 eruption is also visible from here in the valley between the hill of the Observatory and the Monte Somma (photo 16).
• 5) The historical building of the Osservatorio Vesuviano is located at 600 m asl. The Osservatorio was built between 1841 and 1845 on the side of an old building called "Eremo", where travellers used to stop before climbing the mountain. The Osservatorio has survived some notable eruptions (in 1850,1855, 1861, 1868, 1872, 1906, 1929, 1944) without being damaged. It was built on the southern border of the Somma caldera, between two deep valleys bordering the hill. These valleys have now been filled by the lava flows of the above-mentioned eruptions. The Observatory is not open to the public, but organized groups and schools may arrange visits through Centro di Sorveglianza, Osservatorio Vesuviano, in Naples. In the historical building of the Osservatorio Vesuviano is a volcanological museum where old instruments are on display.
• 6) Going towards the crater along the road, the lava flow of the 1944 eruption is visible to the left. The flow was channelled between the Somma walls and the crater. You ascend a small hill called "Colle Umberto", which was formed by the piling-up of many small lava flows between 1891 and 1895. The crypto-dome formed on an old lateral vent, the "Coutrel vent" or "Vent of the Frenchmen", so called because in 1820 a French traveller fell,or threw himself, into it.
• 7) On entering the "Valle del Gigante" or "Valle dell'Inferno" between the Somma and Vesuvius, it is possible to see, on the walls of the Somma, the many dykes that fed its eruptions. The walls are made up entirely of alternating dykes, lavas and pyroclastic deposits. When the road divides further up hill, take the left fork, towards "quota 1000" because the chair-lift (right fork) is not operating (however there is a pleasant bar with a sight-seeing terrace).
• 8) From "quota 1000" there is a short trail (20 minutes walk on ash) which arrives at the crater rim. The products exposed along the trail are mostly the loose pyroclastics of the last phases of the 1944 eruption. At the base of the crater it is possible to see the stream of the 1944 lava flow and, on the flanks, some lobes left by hot avalanches. The avalanches were triggered by the strong tremor during the paroxysmal phase of the 1944 eruption.

 

 
 
 

Access to the crater is allowed only upon buying a ticket and being accompanied by the local volcanological guides.

At the rim of the crater, it is possible to observe the agglutinated scoriae that were emitted during the lava-fountain phase of the 1944 eruption.

The crater was formed as a consequence of a collapse which occurred in the last explosive phases of the 1944 eruption. On the steep wall it is possible to note many of the small lava flows that were emitted during the period 1913-44 (photo 18). In fact, the eruption of 1906 left a much wider crater which was slowly filled with lava until 1944, when a central conelet was approximately at the height of the north-west rim. On top of the rim there is a thick lava flow (1944) covered by scoriae and lapilli of the last phase of the eruption. To the East an apparent fracture is visible. Actually, it is the contact between the lava flows of the 1913-44 crater and those of the 1872-1906 crater. In this section, the 1944 crater is wider than the 1906 crater. The other rim of the 1906 crater is on the west, but is not visible from here.

Proceeding along the rim of the crater, one can observe the whole extent of the southern part of the volcano and, during days with good visibility, it is possible to see the entire gulf of Naples, from the Sorrento peninsula to Cape Miseno, Procida and Ischia. It is also possible to note the large number of buildings which have been built on the vulnerable flanks of the mountain.


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Other images of Herculaneum, Pompei and Oplonti

1 - Herculaneum - Limit of excavated area. The deposits of pyroclastic flows covering the town are visible on the right
2 - Herculaneum -Close up of pyroclastic flows. At least two units are visible
3 - Herculaneum - Columns broken by the weight of volcanic products.
4 - Herculaneum -  Cardo V with a public fountain and a "thermopolium" (fast-food) .
5 - Herculaneum - Peristilium or inner garden . All these areas were originally filled by ashes.
6 - Herculaneum - The dark areas are the original woods and doors. The temperature of the pyroclastic flows was between 100 and 400°C and the carbonization was caused by mineralization processes more then by actual fires.
7 - Herculaneum - Food containers (dolia) in a thermopolium. Pompei was renown for a fish sauce called garum.
8 - Herculaneum - Paintings in the so-called Collegium Augustalis
9 - Herculaneum - Inner structure of an edifice decorated by paintings.
10 - Herculaneum - Paintings in the so-called Collegium Augustalis.
11 - Herculaneum -Original kids graffiti in the Samnitic house.
12 - Herculaneum - The 79 AD sea-shore of Herculaneum  . The level is now at a depth of 4 m below the present sea-level. In these area were found more the 300 skeletons and a boat.
13 - Herculaneum - View of the sea-front of the town. To the lower right is the area of Nonius Balbus and the sub-urban baths..
14 - Herculaneum - Several buildings have the holes made during the early excavation (1700-1800) when they dig tunnels in the deposits of pyroclasitc flows.
15 - Herculaneum - A building with the original upper floor..
16 - Pompeii -  "Vesuvius Gate and Mount Vesuvius.
17 - Pompeii - The Anphitaetrum.
18 - Pompeii - Cast of victims. The cast is obtained by the filling the cavity in the ashes with liquid chalk. the method was inented in 1863 by Giuseppe Fiorelli.
19 - Pompeii - Cast of victims at Nocera gate. The position is suggestive of a death by asphixiation by the ingestion of hot ashes.
20 - Pompeii - Cast of victims with may children in the so called "orto dei fuggiaschi".
21 - Pompeii - Nocera gate: the deposits of the pumice fall and of the surges that destroyed the town.
22 - Oplontis - Villa of Poppea - In the swimming pool is visible the succession of deposits that destroyed the villa.
23 - Oplontis - Villa of Poppea , garden. The succession of deposits is visible on the wall. The cast of the tree show the effect of the arrival of pyroclastic flows that bended the part of the tree emerging above the pumice fall.
 
 

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If you want to know more about Vesuvius read about:

• The history of its eruptions