The Meerkat of Science: Volcanoes

Volcanoes feature all around the world. They are often seen as destructive, dangerous forces, and they certainly are, but they can also breath new life into the regions that surround them, by providing some incredibly fertile land. As a result, there are numerous human settlements near volcanoes (some might say dangerously close in some cases), and this has been the case for centuries. To use Mount Etna as an example, this imposing Sicilian volcano has long played host to townships and cities, even long after people discovered what the mountain truly was.

To understand what a volcano is, we need to understand what the earth itself is.

Founding Forces

The earth formed from the collisions of rocks, billions of years ago. This process was violent, and the primordial earth was a landscape of asteroid impacts and molten rock. At one stage in the earth’s embryonic development, heavier elements sank inward, forming the planet’s hot core. The core is radiating heat through the planet, heat that seeks to escape, and that energy will ultimately reach the surface via weak spots in earth’s crust.

Those weak points are usually found where tectonic plates meet, though this is not always the case. There are patches where the plates themselves are weaker, and where the churning molten rock in the mantle can pierce the surface. Both these points, and the shifting boundaries between tectonic plates, provide us with volcanoes.

Once, the earth’s surface was covered in active volcanoes. In fact, in the earliest days of the planet, these volcanoes helped create the conditions for early life. Materials and gases released into the atmosphere included water vapour, which would cool, and go on to form clouds, rain, rivers and oceans. With the passing of billions of years, the cooling earth meant volcanism gradually decreased. This does not mean it completely stopped, as we know!

Colossal Cones

The stereotypical image of volcanoes is of cones or domes is what most people associate with them. This is not unreasonable, for many volcanoes do look like this. This is down to how they usually form. Material from eruptions is deposited around the volcano, and with multiple eruptions, a structure is built. Over millions of years, and countless eruptions, volcanoes rise from the earth, forming the gorgeous mountains we see in places like the Augustine Volcano. Every such volcano, known as a stratovolcano, is the result of a length natural process, and driven by power found deep in the earth.

A Deadly Power

Whilst volcanoes can – and have – formed a vital component in how life arose on earth, they are clearly dangerous. Whilst many have become extinct, sometimes they have lulled people into a false sense of security. One of history’s most famous eruptions was that of Mount Vesuvius, in 79 AD. The inhabitants of Pompeii and Herculaneum had experienced earthquakes in the years and even the days preceding the eruption, but they had no idea what Vesuvius was capable of. The most recent suspected eruption of Vesuvius to that point had been in 217 BC, some 295 years earlier, so no one alive would have inkling of what was possible. When Vesuvius exploded with a force 100,000 times that of the atomic bombs dropped on Hiroshima and Nagasaki, it unleashed fast-moving streams of hot gas and material, travelling at speeds of at least 100 miles per hour. These flows, known as pyroclastic flows, might have hit temperatures of 1,000 C (1,800 F). These flows were joined by a huge plume of ash that stretched into the sky and turned it dark. Between the pyroclastic flows and the ash, the towns of Pompeii and Herculaneum were completely buried.

Whilst a lot of people may immediately think of lava flows when they imagine a volcano, the biggest dangers often come from these sorts of explosive eruptions, and there are other threats. Halfway around the world, and thousands of years after Vesuvius’ eruption gave us the word volcano, another deadly eruption would produce not only ash plumes and pyroclastic flows, but it would also cause fast-flowing lahars. A lahar is a mixture of pyroclastic material and water, and in the case of Mount. St Helens, which had been capped in ice and snow, the lahars were particularly large.

The lahars swept away roads and bridges, adding to the chaos and devastation in the eruption’s aftermath. What contributed was how St. Helens erupted. Instead of everything blasting skyward, Mount St. Helen’s released her explosive fury via a flank eruption, or lateral eruption. Most of the ash, pyroclastic flows, and consequently the lahars, travelled in a north-easterly direction. The destruction force was in effect focused, making it more dangerous. It is believed 57 people were killed by the eruption, and it caused $3.4 billion in damages (in 2023’s money). This eruption is the worst recorded eruption to impact the USA. However, both the USA and Italy (host to Vesuvius) face much greater dangers…

Sleeping Giants

Take another look at the picture of Mount Vesuvius. She looms over the city of Naples. The city, and its surrounding areas, are home to over three million people, and it’s a fair bet that most of them are distinctly aware of what Vesuvius is capable of. The story of 79 AD and the destruction of Pompeii is a world-wide legend. It is also rather impossible to ignore the volcano itself!

Yet Vesuvius is but a pinprick compared to its closest volcanic neighbour.

You may be wondering ‘why show a picture of the Naples region?’ Well, that region is more than meets the eye. Underneath Naples, a seething cauldron of molten rock and hot gases lurks, and you can see evidence of its past all around the area. Campi Flegrei – also known as the Phlegraean Fields – is not a conventional volcano. It is massive, with a caldera occupying a territory some 12-14 KM wide, and there are pockets of activity across its landscape. It is thought that a major eruption here some 39,000 years ago not only disrupted early human activity, but also proved to be the final death knell for Neanderthals. She has been dubbed a ‘super-volcano’.

Because Campi Flegrei does not fit the classic image of a volcano, it tend to be ‘out of sight, out of mind’. Hundreds of thousands of people now live virtually on top of it, well within the most dangerous zones, but in recent years they have come to be more aware of what Campi Flegrei could become. The region has seen an increase in earthquakes, and there is a constant release of gases at the Solfatara Crater.

Scientists are concerned about Campi Flegrei. It is virtually impossible to predict an eruption far in advance, but nonetheless, she is a heavily-monitored volcano, in no small part due to the considerably number of people living on top of it. She is also not the only super-volcano.

Yellowstone National Park is one of the USA’s most famous tourist spots. It is also the site of one of the largest super-volcanos in the world, and one that has historically erupted with a combination of explosive eruptions, and large lava flows. The region is still geologically active, with features such as the Old Faithful Geyser, among others.

Like Campi Flegrei, Yellowstone is capable of some monstrously powerful eruptions. Like Campi Flegrei, predicting them is extremely difficult. It is possible the next eruption would be relatively mild, but equally, it could be an event that coats much of the USA with ash, blots out the sun, and lowers the earth’s temperature for several years. The most powerful volcanic eruptions have had this effect in the past, and such events will happen again.

The challenge will be to minimise the loss of human life when they do.

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