The Slopes of Lava

A fiery introduction     

When I say “volcano”, most people think about a serial killer, while others think about gems, and fertile land. Some people think about Hawaii or Réunion, while some others think about Mount Vesuvius or Saint Helens. But what exactly are volcanoes? How do they work? Are they good or bad? Don’t worry, we’re going to answer all those questions and dive into some case studies in today’s article! Ready to feel the heat? Let’s delve into the fascinating world of volcanoes! 

What are volcanoes?

           Let’s start by defining what volcanoes are. Volcanoes are big mountains inherited by fairies, and explode every time Tinker Bell turns red and…. I’m joking, obviously that’s not true, I hope you did not believe that. XD

Volcanoes are mountains located over a hotspot (a thinner/weaker/more active part of the Earth’s crust) or on the Tectonic Plates margins. They may happen when plates go over one another, against one another, or depart away from each other, letting magma (melted rocks) flow and store in a magma chamber. When that magma chamber is filled and the volcano cannot further withstand the pressure, it explodes into a volcanic eruption.

How do volcanic eruptions look like?

             A volcanic eruption is usually characterised by an abundant flow of lava (magma once it reaches the Earth’s surface), expulsion of burning ashes, rocks and gases. However, we can identify two main types of volcanic eruptions, coming from two main types of volcanoes: shield volcanoes and stratovolcanoes or composite volcanoes. To make it simpler, I like to call them red and grey (boom) volcanoes. Let’s discover them! 

             Shield volcanoes: Shield or red volcanoes are usually found around divergent plate boundaries (tectonic plates that move away from each other), have large slopes and usually have a low-viscosity lava. This means that the lava is often more liquid and the explosions are gentler. These volcanoes, such as Etna in Sicily, Italy or Mauna Loa in Hawaii, US make up beautiful fountains of lava and ‘rivers of fire’ that attracts many tourists worldwide. They are usually quite safe, even though they may cause damages to nearby houses and fields.

             Stratovolcanoes: stratovolcanoes, or boom (grey) volcanoes as I like to call them are usually found on convergent plate boundaries (tectonic plates that move towards each other) and usually are prone to very high pressures. These volcanoes usually give no warning of eruption, but once the pressure reaches the limit, they explode. They are usually characterised by very hot ash flows that destroy everything around them, ejections of rocks and gases. The ash ejected during their eruption may cover the skies above multiple countries, disturb local and international flights and cause altered weather conditions (some of their gases contribute to global warming, such as CO2, while others reduce the Earth’s temperature such as SO2 (sulfur dioxide)). They are usually very dangerous, especially given that they do not give much warning previous to their explosion. Examples of such volcanoes are Mount Vesuvius in Italy and Mount Saint Helens in the United States. 

How long do volcanoes work?

             Good question! Volcanoes do not constantly erupt, and not all of them do it frequently. In terms of activity, there are three types of volcanoes:

• Active volcanoes: these erupt frequently and constantly. Example of active volcanoes are Le Python de la Fournaise in Réunion and Etna in Italy.

• Extinct volcanoes: these volcanoes will never erupt again. It’s like they would be dead volcanoes. The magma chambers of these volcanoes have been emptied without being refilled, so they will never erupt again. Examples of extinct volcanoes are Mount Buninyong in Australia and Huascarán in Peru.

• Dormant volcanoes: these volcanoes are the trickiest. They can still erupt, but they rarely do, only erupting once in a few decades, centuries or millenaries. However, when they do, they erupt violently and they are very deadly. Often, they do not give any precise signs of eruption, so scientists have to be very careful and precise in their calculations. Examples of dormant volcanoes are Mount Kilimandjaro in Tanzania and Mount Fuji in Japan.

Are volcanoes good or bad?

             This depends on the point of view, and on the level of development and awareness of the population. And yes, I will give you actual facts. Let’s see some advantages and disadvantages of volcanoes. :=)

Advantages:

• Fertile soil: when volcanoes erupt, they eject a lot of volcanic ash and minerals which enrich the soil, making it extremely fertile, and perfect for agriculture. Example: the vineyards used to make the “Lacrima Christi” wine grow on the slopes of Mount Vesuvius.  

• Mineral resources: many precious rocks, minerals and gems form during volcanic eruptions due to the very high pressure, while many others are directly ejected from deep within the crust of the Earth. An example of this would be diamonds, that form under extreme pressure and heat very deep under earth.

• Geothermal energy: volcanic activity is the base for geothermal energy, that uses the heat of the Earth to make Renewable Energy. Some countries like Iceland rely almost entirely on Geothermal Energy;

• Tourism: many volcanoes and volcanic sites are famous touristic destinations. This may be due to old ruins destroyed by the volcano or the beautiful rivers and fountains of lava flowing during a volcanic eruption. Famous volcanic touristic destinations are Mount Etna in Italy and the Yellowstone National Park in the United States.

• Inspiration for cultures, arts and traditions: volcanoes stand at the origin of many legends, traditions, art works, etc… inspiring authors, artists, filmmakers and more, offering an exotic view, a mythical background and a whole lot of adventure. Jules Verne used basic volcanic knowledge to inspire his book “Journey to the Centre of the Earth”, and the Greek Mythology linked volcanic phenomena to Hephaestus or Vulcan, the fire god.

Disadvantages:

• Human casualties: volcanic eruptions are very dangerous, and when unsupervised or badly managed can injure people and claim lives. Examples of very deadly eruptions are the eruption of Mount Vesuvius in 79AD and recently, the eruption of the white Island or Whakaari, New Zealand in 2019.

•  Climate Impact: you heard me well; volcanic eruptions can affect global climate. As we saw earlier, volcanoes eject a lot of gases, amongst which we find Carbon Dioxide (CO2) and Sulfur dioxide (SO2). The eruption of Mount Tambora, Indonesia in 1816 cooled the Earth causing what is known as “the year without summer”, while the eruption of Krakatoa, Indonesia in 1883 causing unusually colourful sunsets around the globe and covering the eruption’s region into darkness for two-and-a-half days due to the ejection of volcanic ash.  

• Destruction of property: volcanic eruptions eject extremely hot lava, ash and multiple other gases, destroying everything around the volcanic, and everything that the volcanic material reaches, whether it be people’s houses, nearby forests, roads or entire cities. I don’t think I need to give you a specific example for this one, as most volcanic eruptions destroy property, depending on how close people live to the volcano.

• Economic losses: governments must invest in good geological material to enable a good volcanic supervision. They must also manage the disaster well, and allocate a fund to the evacuation of people, treatment of injured people and attempts to save the disaster’s victims. The infrastructure and facilities lost during the earthquakes, eruptions and replications will also put a heavy strain on the local and national economy. The eruption of Hunga Tonga-Hunga Ha’apai, Tonga in 2022 caused an economic loss of over 161 million US dollars.

• Transportation disruptions: the clouds of ash and gases ejected into the atmosphere during a volcanic eruption can disrupt shipping routes, and cause flight cancellations, while the ejection of lava and volcanic rocks can block roads and highways. The eruption of Eyjafjallajökull, Iceland in 2010 cause the cancellation of 100 000 flights, while the eruption of Mount Saint Helens, United States in 1980 caused the cancellation of over a thousand of commercial flights in the United States.

     So, are volcanoes good or bad? It really depends. XD They are dangerous, and may cause human casualties, environmental damage and economic losses. On the other hand, they can inspire and entertain humans, may trigger biodiversity diversification and may boost a country’s economy. It depends on the point of view, the type of the volcano, the quality and professionalism of the geological equipment, crew and hazard management, as well as the education of the local people and the development of the country and region near the volcano. It’s not a simple lava flow—there isn't a single way to look at it! 

Sealing the Crater: A Concluding Thought 

          If you are still with me until now, it means you’re really passionate about volcanoes, or I’m just an awesome writer. XD I’m joking. Thank you for sticking with me so far. Hang on, we’re almost done. For the last part of this article, let’s melt it down to the essentials and quickly answer the questions we began with:

• What are volcanoes? Volcanoes are mountains located above a weak or unstable area in the Earth’s crust. They erupt under pressure, ejecting burning lava, rocks and ashes.

• How do they work? Magma flows through fissures in the Earth’s crust, building up in the magma chamber beneath the volcano and increasing the pressure within the volcano. When the magma chamber is completely full and the volcano can’t withstand the pressure any longer, it erupts.  

• Are they good or bad? Volcanoes are dangerous, very deadly phenomena that are out of our control. However, when managed well, they can be a source of riches and abundance for the local people, environment and economy.

         And that’s it! By now, you should know all the basic essentials about volcanoes. However, this article only scratches the surface of volcanology and geology. Hopefully, it’s enough to light up in you a spark of passion for geophysical geography, and encourage you to explore the topic even deeper. Wishing you a lava-tastic journey through the fascinating world of geology!!