Italy 2019

Italy: The Classic Volcanoes

In October 2019, we ran our Classic Volcanoes tour in Italy for the third time.

Day one – arrival

The tour group gathered today at our hotel in Naples. We were able to take advantage of the hotel’s roof terrace with a spectacular view of Vesuvius as a venue for our welcome meeting.

Day two – Vesuvius & Herculaneum

Our first stop of this year’s trip was Vesuvius, regarded by many as the most famous volcano in the world. Its eruption in 79AD that destroyed the Roman cities of Herculaneum and Pompeii is the world’s best known eruption. The eruption was described by Pliny the Younger and is the type ‘Plinean’ eruption; his account was the first ever scientific description of a volcanic eruption. The eruption emitted 1km³ of white phonolitic pumice, 2.6km³ of grey tephriphonolitic pumice. The city of Pompeii was under the major pumice fall out. The volcano then emitted 0.37km³ of pyroclastic material in six different pyroclastic density currents (PDCs). The people who had not yet fled Herculaneum were killed by the pyroclastic surge of the first PDC. The third PDC completely buried Herculaneum. The 4th overwhelmed Pompeii killing around 1,500 people. Vesuvius will erupt again and is currently in a period of repose, marking the end of one of its eruption cycles.

After our visit to the summit of Vesuvius, we visited the Roman city of Herculaneum and saw for ourselves how the eruption had buried the city under 15-18 metres of volcanic material, which had also beautifully preserved it. The site was re-discovered in 1709AD and numerous excavations since then have uncovered approximately 20% of the site (12 acres/5 ha), with many more buildings and streets still remaining covered, underneath present day settlement. Highlights of the site include the wooden screen and bed surviving in one building, the painted sign outside a shop showing the types and prices of the wine on offer, and the mosaics in the baths.

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Day three – Pompeii

The whole day was spent in Pompeii, exploring the remains of the Roman city preserved by Vesuvius’ famous 79AD eruption. James’s wife Abby, who has a background as an archaeologist, guided for the day.

The eruption which buried Pompeii is traditionally believed to have occurred on 25th August 79AD, however recent analysis of botanical remains and clothing fibres, along with some graffiti, suggest that it actually happened in the autumn, probably on 25th October 79AD. The city has yielded a wealth of archaeological evidence over the last 250+ years of excavations. The eruption enveloped the city, killing up to 2,000 people. Many of the bodies have been identified by the voids left in the volcanic material – in the 19th century, it was realised that if plaster was used to fill the spaces left by the decomposed bodies, then casts of the victims could be created. These casts are poignant reminders of the human cost of the eruption.

Our group was shown many of the houses in the city along with the numerous thermopolium (fast food outlets) and other shops. We also saw the surviving amphitheatre – the earliest surviving stone amphitheatre anywhere in the world. We also examined the wheel ruts left in the stone by the Roman carts and found out more about the complex system of access and one-way streets which must have existed in early 1st century Pompeii. Around ⅔ of Pompeii has been excavated, but approximately 54 acres (22 ha) remain unexcavated.

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Day four – Campi Flegrei

Today we visited Naples’ less well known volcano: Campi Flegrei. This volcano erupted 37,000 years ago with a Volcanic Explosivity Index (VEI) of 7 – 100 times more powerful than the 79AD eruption of Vesuvius. This was the biggest eruption in the Mediterranean in the last one million years, and emitted 80km³ of ignimbrite, forming a caldera 12km across. The caldera erupted again 15,000 years ago depositing Neapolitan Yellow Tuff. Since these giant eruptions, there have been 56 smaller eruptions. The most recent was in 1538, which formed Monte Nuovo. This was our first stop of the day, and the first photo is the view looking into its crater. The eruption lasted just a week and most of the cone formed in 24 hours. The eruption began in a Surtseyan style, erupting underwater, then switched to Strombolian, when the cone was above sea level. The eruption included a pyroclastic flow that went 7km out to sea and killed 24 people who had climbed the crater to look inside.

Right next to Monte Nuovo is Lago Averno. This lake lies in a tuff cone that was created by a Plinian eruption 3.7 thousand years ago. Lago Averno, in Classical times, was believed to be the entrance to the underworld, and both Aeneas and Odysseus entered from there.

Our next stop was the Temple of Serapsis in Pozzuoli in the centre of the Campi Flegrei caldera. This ‘temple’ was a former Roman market and was on the cover of the world’s first geology text book ‘The Principles of Geology’ by Charles Lyell. The ‘temple’ is famous to modern geologists because it shows how the ground level has risen and fallen due to the inflation and deflation of the magma chamber beneath. Visible on the pillars are holes bored by marine molluscs from a time when the land fell below sea level. It has since risen again. Also in Pozzuoli, we learnt how 40,000 people were evacuated in 1982 when earthquakes and bradyseismic movements led to fears that a Monte Nuovo style eruption might occur in the heart of the town. Luckily it did not occur, but could occur in the future – making Campi Flegrei a very dangerous volcano indeed.

Our final stop of the day before boarding the overnight ferry to the Aeolian Islands, was the Archaeological Museum in Naples, where we saw many of the beautiful artefacts, mosaics and frescoes found at Pompeii and Herculaneum.

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Day five – Lipari

The day started with our overnight ferry from Naples arriving at Stromboli at 6am; some of the group got up half an hour earlier and witnessed the lava erupting as the ferry passed by the island. After this, the ferry called into Panarea and Salina before we disembarked in Lipari. Once ashore, we drove to Porticello, to see the Rocche Rosse obsidian flow and associated rhyolite pumice which erupted in around 1220. The pumice here has been extensively mined in the past; it was used in toothpaste, soap, beauty creams and abrasive/polishing pastes. After a swim, we continued around the island to a viewpoint where we could see Vulcano island. We then continued on to check in to our overnight hotel and enjoy a free afternoon on the island – the main highlight for many being the Volcano Museum.

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Day six – Stromboli

Today we visited Stromboli volcano – the most ‘diligent’ volcano on earth that has probably been continuously erupting for the last 5,000 years. Due to these continuous eruptions, Stromboli is possibly the best place in the world to go to be able to get a chance to see lava. It lends it’s name to all ‘Strombolian’ type eruptions, but it is a stratovolcano not the type of volcano typically produced by Strombolian eruptions. However, for the last 2,500-5000 years, Strombolian eruptions have been its most typical eruption. From time to time the volcano does erupt with larger eruptions including in 1919, when blocks of several tonnes fell on houses killing 4 people, and in 1930, when vigorous explosions and a small pyroclastic flow killed 6 people. Right now the volcano is also erupting with larger eruptions. On July 3rd 2019, a person was killed by an eruption that had an eruptive column 4km high, and on August 28^th a yacht raced away from a pyroclastic flow emitted by another large eruption (footage of this can be seen by doing a search on social media). Due to the current strong activity we were unable to hike to the top of the volcano, but some of our group hiked to the observatory at an alitude 300m. As the sun went down, we also viewed the eruptions by boat from the new 2-mile exclusion zone that has been imposed since the August 28th eruption. All in all, it was a great day – thank you Stromboli for putting on a great show!

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Day seven – Vulcano

Today we visited the island of Vulcano. Not only does this volcanic island lend its name to all the world’s volcanoes, it is also the location of the ‘type’ Vulcanian eruption. Even though this is the ‘original’ volcano it is quite unusual, because the volcanic eruptions have been happening in a north-moving trend instead of directly on top of each other. The oldest part of the island is an infilled caldera, which is cut into by a younger caldera, which contains La Fossa cone, the source of eruptions since classical times. This is all attached to what was a smaller island: Vulcanello, which first emerged in 183BC and was joined to the island of Vulcano in 1530. There are three craters on Vulcanello. The most recent eruptions on Vulcano were in 1898-90. On the summit of La Fossa, there are some impressive steaming fumeroles and solfataras. The visible sulfur is formed by the oxidation of hydrogen sulfide. The striking feature right next to the port in Vulcano is La Faraglione, a cinder cone that was tunnelled and mined for sulphur and alum. At the end of the day, we took the hydrofoil across to Milazzo on the north coast of Sicily, where we spent the night.

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Day eight – Mount Etna

Today we visited one of the world’s most famous volcanoes: Mount Etna. Unfortunately, the weather was foul and the cable car couldn’t run due to high winds. Nevertheless we travelled to the top of the cable car station by 4×4 vehicle and the group then had an explanation of the geology of this immense volcano. Some of us went for a walk in the fog, examining lava close up – but the weather conditions were poor.

Fascinating facts about Etna are, that it is Europe’s highest and most voluminous volcano. It is one of the world’s most active volcanoes, but it hasn’t killed more than a few hundred people because it’s eruptions are not explosive. There are 2 types of eruptions, currently almost continuous Strombolian type eruption from the summit and, less frequently, effusive lava-flow-emitting eruptions from its flanks. These eruptions represent a real threat to property but less to life. After our visit to Etna, the group were taken to their hotel in Catania for the final night of the tour.

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Day nine – departure

After an epic trip through the highlights of Italy’s volcanic regions, the group dispersed today, with some staying on for an additional day or two in Sicily, while others headed home. Thank you to the group for good company and interesting geological discussions!