Augustine Volcano, Alaska © U.S. Geological Survey / Image Creator McGimsey, Gam
From ancient times until the moment this article was penned, volcanoes and their recurring activity have captivated, amazed, humbled, but also deeply affected the people of our planet.
Whenever we talk about volcanoes, we speak of unimaginable power and extraordinary character and strength, we see the absolute force of nature reminding us how powerless and small we are before it.
But what is the origin of these gigantic natural phenomena?
The origin of volcanoes lies in the constant divergent or convergent movement of the tectonic plates that cover the earth beneath its crust. Driven by the constant changes in temperature and pressure under the crust and the underlying mantle, convection currents form, eventually leading to the eruption of molten material and hot magma from the Earth’s interior through the cracks in the crust, usually where two tectonic plates meet. The hot magma rises from the hot spots underground and erupts as flowing lava through these cracks, creating different types of volcanoes.
After centuries of studying this phenomenon, scientists now know that every volcano goes through four phases during its long life. In the first phase, pressure builds up inside. The movement of the tectonic plates creates a magma chamber that gradually fills with hot magma. When this chamber is full, the second phase begins, in which the hot magma is ejected through the volcano’s crater. The ejection can sometimes be violent, in the form of a spectacular explosion of hot lava, but sometimes it just flows slowly downwards or into the sea (if it is under water). In either case, this phase leads to a third one, the ‘dormant’ phase. As the magma chamber empties, the pressure drops and the volcano goes into “sleep’. It may sleep for a few years, for ages, or forever, when some volcanoes enter the fourth and final phase of their long existence, called the ‘extinct’ phase.
It is estimated that today about 80 per cent of the Earth’s surface, including below sea level, is of volcanic origin. Volcanic eruptions over hundreds of millions of years have shaped the geographic landscape of the Earth that we know today, with its mountains, plateaus and plains
The oldest lava found on Earth near the village of Inukjuak on Hudson Bay in Canada is estimated to be about 3.825 billion years old.
Throughout history, the eruptions of volcanoes have been recorded and documented. Pliny the Younger was an eyewitness to the massive eruption of Mount Vesuvius in Roman antiquity in 79 AD, and it is to him that we owe the first officially documented volcanic eruption in history. Unfortunately, Pliny was overcome by the volcanic fumes on his arrival in Pompeii and died in Stabiae, another ancient Roman city near the volcano. The eruption of Vesuvius in 79 AD destroyed the Roman cities of Pompeii, Herculaneum, Oplontis, Stabiae and several other villages. The lava and ash produced by the eruption covered the settlements and, although they destroyed life in these places, led to their remarkable preservation, which offers archaeologists valuable information about the way of life and customs in Roman times. Pompeii is indeed one of the best preserved archaeological sites in the world.
The deadliest volcano in the world, however, is considered to be Tambora in Indonesia. Its eruption in 1815, the largest ever recorded, killed nearly 100,000 people directly or indirectly, according to History.com.
The total number of volcano-related deaths today is estimated at 238 867.
Today, there are about 1,350 potentially active volcanoes worldwide. About 500 of these volcanoes have erupted in historical times. Australia is the only continent without current volcanic activity, but is home to one of the largest extinct volcanoes in the world, Tweed. It is estimated that 800 million people in 86 different countries live within 100 km of an active or potentially active volcano. Many of today’s active volcanoes are located along what is known as the ‘Ring of Fire of the Pacific’, a chain of underwater volcanoes and sites of strong seismic activity at the edges of the Pacific Ocean. About 90 percent of all earthquakes occur along this ring of fire, and 75 percent of all active volcanoes on earth are found there. There are entire countries with large populations that lie on the ring of fire and are therefore constantly at risk. These include Indonesia (267 million people), the Philippines (103 million people) and Japan (127 million people).
Mount Fuji, the volcano off the east coast of Japan, is the highest and most famous mountain in Japan. It is also an active volcano in the Ring of Fire, located only 100 km from the Tokyo-Yokohama metropolitan area. Mount Fuji has erupted more than 15 times since 781. It is still considered active, although it has been dormant since its last eruption in 1707 and the last signs of volcanic activity occurred in the 1960s. Fuji is monitored 24 hours a day given concerns about the extensive damage an eruption would cause near a large populated area.
The United States ranks third after Indonesia and Japan in the number of historically active volcanoes, with most of these found in the Cascade Range and Alaska. In addition, about 10% of the volcanoes that have erupted in the last 10 000 years are in the United States. The world’s largest eruption of the 20th century occurred in Alaska in 1912 (now Katmai National Park and Preserve).
When a tectonic plate moves slowly over a hot spot, a chain of volcanoes or volcanic islands can form. The best examples are the islands of Hawaii and Samoa, which were formed in this way. Mauna Loa is one of the five volcanoes in Hawaii (US state) and the largest volcano on Earth, both in terms of mass and volume. When measured from the ocean floor, which is the actual base of the mountain, Mauna Loa is 9 km high. It lies about 5 km underwater and rises “only” about 4 km gradually above sea level, in the form of a shield. The volcano occupies about 51 percent of the island of Hawaii. Mauna Loa, which means “Long Mountain” in Hawaiian, is the largest active volcano on the planet today. The current eruption, which began on 27 November 2022, is the 34th recorded since 1843. The most recent eruption is still ongoing.
The US Geological Survey volcano alert level was at WARNING, with daily updates issued for Mauna Loa. The alert level has now been downgraded to WATCH as experts believe Mauna Loa’s eruption is slowly coming to an end and the output of lava and volcanic gases is greatly reduced. At one point, the daily bulletin reported a lava flow coming dangerously close to a vital highway used by residents and tourists to get from the east to the west side of the island. After a crisis that lasted for days, the road was finally no longer under immediate threat from the lava. In addition, flight restrictions were imposed in the area up to 1,500 feet above the ground. Authorities advised residents to prepare for evacuation should the lava flow towards populated areas. So far, however, the lava is not threatening any homes or communities and no evacuation orders have been issued.
Kilauea, a smaller volcano nearby, has also erupted since September 2021. This rare phenomenon of two volcanoes erupting at the same time attracted many tourists to the area.
Iceland is one of the most active volcanic regions on earth, with eruptions occurring on average every four years. These eruptions, sometimes small and quiet, sometimes explosive, can last from minutes or hours to months or several years. Iceland’s geological position is the main reason for the country’s intense volcanic activity. Large amounts of magma filling the cracks in the earth’s crust created by the spreading tectonic plates lead to frequent eruptions along the rift zone. Icelandic volcanoes regularly make headlines, especially on the European continent, as they sometimes disrupt the normal lives of all Europeans, not just the locals. One example is the Eyjafjallajoekull volcano, which in 2010 brought all air traffic over Europe to a standstill for several days as it spewed enormous amounts of ash into the air. A more recent example is the Fagradalsfjall volcano, which erupted on the Reykjanes peninsula.
Besides the famous Vesuvius, there is another infamous volcano in Italy that makes headlines. In 2021, erupted volcanic material from Mount Etna caused it to increase in height by about 30 metres in just 6 months. In 2022, the volcano, which can be visited up to the crater during dormant periods, was active again. At the base of the cone, on its northern side, a fissure has opened and a lava flow is pouring into the valley on the eastern side of the volcano, called Valle del Bove. In recent years, the lava reached the outskirts of the villages at the foot of the volcano several times and people had to move.
But another phenomenon worries scientists when it comes to Etna. They have noticed that Etna is slowly but surely slipping. The mountain is moving very slowly, but geologists have not yet been able to understand what has caused the volcano to move. At the moment, they can only ‘keep an eye’ on the active volcano, because it is impossible to say whether an acceleration of this process will occur in the next few years or centuries. However, the fear of a catastrophic collapse of the mountain is great, especially since it could also trigger a devastating tsunami that would hit the coasts of both Italy and Greece.
Further west, the Canary Islands in the Atlantic (which are part of Spain) have a volcanic history that began about 70 million years ago. The Canary Islands region is still volcanically active, with the impressive Mount Teide (3,718 metres high) on Tenerife and some smaller (but equally dangerous) ones on the other islands. The most recent volcanic eruption on the islands, and the most recorded to date, occurred on La Palma in 2021.
In 2021, Cumbre Vieja erupted and, due to local weather conditions, volcanic ash from La Palma reached the nearby island of Tenerife, causing significant disruption to air traffic. The ash and smoke caused by the eruption affected all life on the island and had a major impact on tourism, an important source of income for the locals.
Ash rain can have a significant impact on crops during a volcanic eruption. Physical effects due to additional weight of the ash on the leaves, partial spilling or snapping of branches – all this prevents the natural growth process of the plants and can ultimately lead to crop failures.
Ash in the air can also affect the quality of human life. The abrasive particles of ash can scratch the surface of the skin or eyes, causing discomfort and inflammation. If inhaled, volcanic ash can cause breathing problems due to the harmful aerosols and toxic gases that make it up. It can even damage the lungs and eventually lead to suffocation. It can be particularly harmful to children, older adults and people with pre-existing respiratory or heart conditions.
Economic activity can be affected after a volcanic eruption, as it is difficult for businesses to get back to work and recover afterwards. Natural habitats are often affected and animals and plants are destroyed. It is now proven that an increased volcanic channel arm in a region due to volcanic activity will most likely lead to a decline in property prices and other economic indicators in the region. Economic activity is interrupted, transport is affected or even temporarily stopped, which can lead to losses of several million euros.
It may come as a surprise, but volcanic activity can also have a positive impact on the environment and the people who live in these volcanic regions. Over the years, it has been shown that volcanic eruptions and the processes associated with them have also directly or indirectly helped humanity.
Despite the danger of living near these volcanoes, soils with high volcanic activity are also the most fertile because they contain important nutrients such as potassium and phosphorus, which are released when the lava erupts. Volcanic soils are therefore ideal for growing vegetables, especially root vegetables (potatoes, carrots, onions).
Many of the metallic minerals that are mined around the world today, such as gold, silver, lead, copper or zinc, are found deep inside extinct volcanoes. Diamonds are brought to the earth’s surface by a certain type of magma called kimberlite. For this reason, mining towns have often developed near volcanoes. Volcanoes also provide much of the building materials used today.
Among the documented benefits of volcanic activity is the ‘cooling effect’. For example, after the eruptions of El Chichón in Mexico in 1982 and Pinatubo volcano in the Philippines in 1991, the air cooled by over half a degree Celsius. Eruptions thus practically help to combat global climate change by keeping the atmosphere cooler.
Another long-term benefit of volcanic activity is the creation of new land. All the Hawaiian islands are the result of volcanic eruptions, where hot lava meets the much cooler seawater and is then transformed into new, fertile land in a long process that can take many years.
Oddly enough, volcanoes are also a source of water, both from the magma and from the steam that rises from the ground with the magma. over the course of 4.5 billion years, the amount of water produced by volcanoes has provided the water we have on Earth,” estimates Dr Janine Krippner, a volcanologist, for accuweather.com.
Geothermal energy associated with hot springs of volcanic origin is also very important and is widely used in countries such as Iceland and New Zealand. According to scientists, the places with the highest underground temperatures are in regions with active or geologically young volcanoes.
So there is much to lose, but also much to gain by the existence of these still mysterious natural phenomena. They cannot be tamed and are very unpredictable, but they could also be seen as benefactors that should never be taken for granted… some restless giants of the modern world.
