According to the dictionary of the Royal Spanish Academy, a volcanic eruption is defined as the emission of solid, liquid or gaseous materials through openings or cracks in the earth’s crust . All this matter, apart from gases, corresponds to what we call lava, molten rock that can reach more than 1000 ° C. However, lava that has not yet risen to the earth’s surface is known as magma , the protagonist of our article today.
Magma is nothing more than a molten mantle , the layer that is below the earth’s crust and that goes from 33 km to 2900 km deep , reaching the outer limit of the earth’s core.
So basically, a volcanic eruption occurs when magma decides to break through the earth’s crust and go for a walk on the surface, sowing chaos and destruction. But what geological processes are behind this phenomenon? The truth is that there are several ways that a volcano is created, in all of them it is necessary to melt part of the rock of the earth’s mantle, to create the magma. This process may be due to three phenomena, two of them related to plate tectonics , parts of the lithosphere that form the puzzle of the earth’s crust.
According to the theory of plate tectonics, plates move very slowly over the Earth’s mantle. Both when two divergent plates separate from each other , and new crust arises between them; or when they collide (converge) and one of them underlies the other, the chances of an eruption are increased, since pathways can be created that facilitate the magma to reach the surface. In addition, volcanoes can also be created in areas called hotspots , which are not located at the boundaries between plates but in the middle of them, giving rise to what is known as intraplate volcanism.
In all three cases, the geological process of the eruptive process is the same. Everything depends on the balance between two forces, the lithostatic pressure, which the earth’s crust exerts towards the core, and the pressure of the magma, which counteracts the first. The pressure of the magma can increase when gas bubbles form, which rise to the area adjacent to the earth’s crust and explode with force, when this occurs with many bubbles at the same time, the crust explodes as if it were a stirred fizzy drink. There may also be the so-called discharge effect , usually caused by landslides or the melting of large glaciers, which reduces the lithostatic pressure, allowing the magmatic chamber to make its way outwards. Something that worries geologists, since the thawing produced by climate change could lead to an increase in volcanic activity at a global level.
Neither the timing of the eruptions nor their duration is easy to predict. However, volcanologists do not stop investigating with new technologies in order to avoid irreparable damage.
