FEBRUARY, 2021 – Italy is a seismically active country with a long history of earthquakes and volcanic eruptions. In the days of the Grand Tourists the volcano of Vesuvius was very active. Visitors would often watch a nightly show of glowing lava and plumes of gas and ash, pouring from the crater. The science of archaeology began in Italy with excavations at Herculaneum and Pompeii starting in the 1740s and 1750s. Probably the most famous volcanic eruption in Europe was the Vesuvius eruption of AD 79 when the Roman cities of Pompeii and Herculaneum were engulfed with lava, ash and volcanic debris.

Today the volcano of Etna, on the island of Sicily is active, and flows of lava regularly make their way down the flanks of the mountain. Volcanoes and earthquakes are all part of the endless geological cylce of processes that keep our planet dynamic and ever-changing. A volcanic eruption is a massive explosion of molten rock and gases that pour into our atmosphere and then fall under gravity back to Earth. It’s all part of a giant recycling process. When a volcano erupts vast amounts of molten material, ash and tiny volcanic stones are launched into the atmosphere. This debris will gradually fall back to Earth and over time consolidate into new rock surfaces and eventually create mineral rich, fertile soils, perfect for farming. Similarly tongues of lava, molten rock, weave their way under gravity from volcanic peaks to the plains below. It is a huge, never-ending process of construction, erosion and destruction that repeats itself infinitely. Effectively it is these processes of change that create our ‘Restless Earth’.

The Earth’s surface is made up of a series of vast tectonic plates, which move slowly in relation to one another, a bit like the pieces of a badly-made jigsaw, where the individual pieces of the jigsaw don’t fit together perfectly. Instead they bump and push and slide against one another. Some of the plate boundaries are zones of construction, where the plates are moving apart, for example the Mid-Atlantic Ridge that divides the Atlantic Ocean (roughly) into east and west segments. Other plate boundaries are zones of subduction where two plates are pushing together and one plate moves under the other one, for example the Pacific Ocean plate and the Andean Plate of South America. Over millions of years this subduction zone has created the Andes Mountain Range.

However, volcanic activity and earthquakes often occur far from the plate boundaries. Many of the Earth’s tectonic plates are criss-crossed with complicated patterns of faults, areas of fracture or weakness where movement can occur. A perfect example is the San Andreas fault running from north to south parallel to the coast of California and the Pacific North West of the United States. The San Andreas Faultline has numerous smaller fault lines running from it, roughly at right angles to the main fault line. These faults can be very active and generate numerous earthquakes and tremors. The Mendocino Fault or fracture zone (map below – left) is a particularly dynamic section of the San Andreas Fault complex.

_{San Andreas Fault, USA West Coast and lateral faulting (left). Multiple lava flows from Vesuvius (right)}

Volcanoes tend to attract our attention because of their vast size and scale. Vesuvius, for example, has been actively observed and monitored for almost two thousand years. Pliny the Elder, a Roman historian died in the eruption of Vesuvius in AD 79. His nephew Pliny the Younger wrote several letters recording the event. Pliny the Younger watched the eruption and described the explosion of Vesuvius as being similar (in appearance) to a pine tree that grows very tall and very high, with a straight trunk stretching up into the sky before spreading out into a series of horizontal branches. The vacuum created by this vast explosion of material into the atmosphere created a massive onshore wind at sea level which would have made escape, by boat, completely impossible. In fact Pliny the Elder died in the eruption, whilst his nephew, watching from further away at Stabiae survived.

Whilst volcanoes can be intimidating they are also fascinating. I like to think of them as Nature’s pressure cookers, erupting steam when the pressure beneath the mountain gets too great. Here’s a gallery of images from Southern Italy and Sicily – painted by early visitors and also more recent photos from when I have visited Vesuvius and Etna with friends and clients over the last ten years.

_{Bay of Naples and Vesuvius – 18th century painting showing the Flegrian Fields smoking and burning.}

The Vesuvius and Etna photos show very clearly the barren slopes surrounding these volcanoes. When a volcano is active there is a constant level of sulphuric gas emitted from the crater and surrounding fissures. From time to time there are lava flows and explosions associated with eruptions. This spewing of material from the crater down the mountainside creates huge fields of pumice (volcanic ash) and basalt (cooled lava) along with various mineral deposits. Over time these volcanic materials break down and eventually create fertile soil which is excellent for farming. On the lower slopes of Etna there are vineyards, fruit farms and even a honey-maker all benefitting from the mineral rich soils of a volcanic area.

The final photo in the gallery was taken by a member of the US Navy, from the naval base at Sigonella, just to the south-east of Mount Etna. This brilliant photo shows very clearly the plume of debris being pumped into the atmosphere and the apparent proximity of the aeroplanes on the ground. It is worth noting that the distance from Sigonella to Mount Etna is about 40 kms. It’s a really great photo – thanks to MSC 2nd Class Austin Ingram.

Lastly a special thank you for another really great photo by Mark Wilson from the Department of Geology, College of Wooster, Ohio. This photo shows Etna from the south and clearly reveals the numerous lava streams and fields of volcanic material erupted from the volcano over the decades. The crater and peak of Etna is top left in the photo. An old lava flow can be seen left centre, snaking down the hillside. An older crater, in the foreground (right) shows the vegetation succession beginning to get to grips with the bare rock of the southern slopes. Finally, the mountain hut or refuge (lower right) has been beautifully built out of the basalt rocks of the local area and consequently blends perfectly with the locality.

Notes:

• For a little more on the history of archaeology – why not read: Vesuvius and the eruption of 79 AD
• For a general introduction to earthquakes in Italy: Earthquakes in Italy
• Further dramatic volcanic activity seen at Etna, 10-11 February, 2022. Lava ejected from crater and moving down south-east slopes of the volcano. https://youtu.be/kaqZsDuGAxM
• The Educated Traveller writes about life in Italy and offers tailor-made journeys in Venice, Le Marche, Dolomites and Sicily. To really discover Italy and meet the locals contact: janet@grand-tourist.com – it’s an exceptional way to really discover Italy.

Further reading:

• For a fascinating diversion from every day life – why not visit our blog: Greyhound Trails Travel

• Written: 12th February, 2022
• Updated: 4th May, 2024

Lastly – a very interesting and detailed ‘Geological Map of Etna’ published by Stefano Branco (et al) Roma, 2011. Excellent summary of Etna’s long and active volcanic history.

• Written: 12th February, 2022
• Updated: 4th May, 2024

_{View of Vesuvius seen from Pompeii – Fitzwilliam Museum, Cambridge}

4th May 2024

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