A volcano is an opening in the ground through which magma finds an escape door. Volcanoes can erupt, like Etna or like recently Fagradalsfjall in Iceland.
The potential eruption of the Fagradalsfjall volcano has put Iceland on alert. The earth prepared for a volcanic eruption. After a series of earthquakes, the authorities declared a state of emergency. As of December 18, 2023, the Icelandic volcano is erupting without causing any major disruption to air traffic at this time.
To better understand the current situation in Iceland, here is everything you need to know about volcanoes.
How to define a volcano?
A volcano can first be characterized by its shape: it is a more or less pronounced relief, generally conical in shape. It is characterized by an opening in the earth’s crust. It is where the internal dynamics of the Earth are in relation to the surface (air or underwater) and atmosphere of the planet.
A volcano is the exit point for molten rock, called magma. Lava, volcanic ash and gases escape through this opening. Eruptions are primarily caused by gas pressure,” a bit like when carbon dioxide pops a cork from a bottle of champagne » summarizes the Canadian Risk Information Service.
Magma ejected by Earth’s volcanoes is a mixture of molten rock and solvent gas. Magma is formed by the melting of solid materials in the earth’s crust and upper mantle.
How is a volcano formed?
The outer layer of the Earth, the lithosphere, is divided into tectonic plates. These plates are movable relative to each other and can collide. Most volcanoes arise at the contact of these tectonic plates, we then speak of interplate volcanoes.
Volcanoes arising inside the plate are much rarer, we are talking about intraplate volcanism.
What are the 4 types of volcanoes?
There are 4 types of volcanoes: Strombolian, Volcanic, Hawaiian and Pelean. They are distinguished by the type of eruption (depending on the nature of the magma). The same volcano can have different types of eruptions during its existence.
Volcano effusive has eruptions without explosions, with abundant lava flows. Volcano explosive has eruptions accompanied by explosions and lots of ash.
- Volcanoes Stromboli are both effusive and explosive,
- Volcanoes Vulcans have explosive eruptions without lava flows (too viscous),
- Volcanoes Hawaiian are effusive (or lava),
- Volcanoes peleans they are explosive, with eruptions of stones, ash and toxic gases (fire clouds).
The shape of a volcano directly depends on the type of its eruptions, which can always be of the same type or can change over time.
What are the 3 parts of a volcano?
The volcano consists of 3 main parts:
- THE magma reservoirlocated under the earth’s crust,
- One or more volcanic ventsconnecting the tank to the surface,
- THE crater.
What are the characteristics of a volcano?
Volcanoes are basic structures on our planet. These are ” Earth’s geological architects “, National Geographic sums it up well. Volcanoes are estimated to be responsible for more than 80% of our planet’s surface.
We distinguish active volcanoes from extinct volcanoes. Active volcanoes, as their name suggests, are likely to erupt on human time scales (years, decades, centuries, or millennia). Active volcanoes alternate periods of activity with periods of rest.
How does a volcano erupt?
Volcanoes are preceded by volcanic earthquakes, called aftershocks. As magma leaves the magma chamber to rise to the surface, it hits the walls, pushing out solid pieces and causing degassing bubbles. This activity causes seismic vibrations, monitored by seismographs as warning signs of an eruption.
If the magma eventually leaves the magma chamber, it is because of the accumulation of gas that mixes with the magma and increases the pressure. When the pressure is too high, magma is pushed towards the surface, causing an eruption. An explosion of magma in the form of lava can go through different paths: the main chimney or other chimneys. This can also cause an ash or gas cloud to form.
During a volcanic eruption, there are different types of volcanic ejecta:
- THE ash : very fine particles from rock or magma during spraying,
- THE slag : small pieces of lava solidified in air or after being ejected,
- THE lapilli : fragments 2 to 64 cm in size that come either from the bowels of the volcano or from solidified lava and then pulverized outwards,
- THE volcanic bombs : these are pieces larger than 64 centimeters, lava that solidified while in the air, after being ejected.
How hot is volcanic lava?
As magma rises from the magma chamber towards the surface, it becomes lava. When it gets outside, it reaches temperatures from 500 degrees to 1200 degrees Celsius. When it is on the surface, it is in contact with air and rock, which leads to its gradual cooling and subsequently to its solidification.
What volcano is currently erupting?
For real-time information on active volcanoes and recent earthquakes around the world, you can check out this map. The Global Volcanism Program (GVP), the US volcanology research program, also maintains a database of Earth’s volcanic eruptions.
This year, November 13, 2023, volcanoes are attracting a lot of attention. Etna erupted in Sicily: it is the highest active volcano in Europe. The risk of eruption concerns Ireland, a state of alert is in place in the area of the volcano Fagradalsfjall, which could erupt.
What are the 7 most dangerous volcanoes in the world?
We can list these 7 particularly dangerous volcanoes in the world:
- THE Vesuviusin Italy, one of the rare volcanoes still active in Europe,
- THE Mount Rainierin the United States, closely watched because of a large glacier (which would add to the currents in the event of an eruption),
- THE Novaruptin the United States, which caused the largest eruption of the 20
- THE Pinatuboin the Philippines, at the birth of the 2nd largest eruption of the 20th century,
- THE Mount Saint Helensin the United States, responsible for the country’s most destructive eruption in 1980,
- L’Agungin Indonesia, eruption for 11 months in 1963,
- THE Mount Fujiin Japan, under scrutiny since the 2011 earthquake.
How many volcanoes are there in the world?
10,000 volcanoes have been recorded on Earth’s continents, 1,500 of which have erupted within the last 10,000 years.
The mid-ocean ridge, an underwater volcanic chain, crosses the oceans for a distance of 60,000 km. This volcanic chain averages 1,500 km in height, but rests at depths below 4,000 meters. These volcanoes are the most numerous, but also the least known.
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