What are volcanoes?
Volcanoes are basically the raptures in the crust of our planet Earth that allows hot gases, molten lava and some rock fragments to erupt by opening and exposing the magma inside.
How do volcanoes erupt?
It is so hot deep within the earth that some rocks slowly melt and turn into a thick flowing matter known as magma. Since it is lighter than the solid rock around it, the magma rises and gets collected in magma chambers. Eventually, some of the magma pushes through fissures and vents in the earth’s surface. Hence a volcanic eruption occurs and the erupted magma is known as lava.
We need to understand the Earth’s structure to know how volcanoes erupt. At the top lies the lithosphere, being the outermost layer that consists of the upper crust and mantle. The thickness of the crust ranges from 10km to 100km in mountainous locations and mainly consists of silicate rock.
Why do Volcanoes Erupt?
The Earth’s mantle within the crust is classified into different sections depending on individual seismology. These include upper mantle, that ranges between 8 – 35 km to 410 km; transition zone ranges from 400 – 660 km; lower mantle lies between 660 – 2891 km.
The conditions change dramatically from the crust in the mantle location. The pressures rise drastically and temperatures rise up to 1000 oC. This viscous and molten rock gets collected into large chambers within the Earth’s crust.
Since magma is lighter than surrounding rock, it floats up towards the surface and seeks out cracks and weakness in the mantle. It finally explodes from the peak point of a volcano after reaching the surface. When it is under the surface, the melted rock is known as magma and erupts as ash when it comes up.
Rocks, lava and ash are built across the volcanic vent with every eruption. The nature of the eruption mainly depends on the viscosity of the magma. The lava travels far and generates broad shield volcanoes when it flows easily. When it is too thick, it makes a familiar cone volcano shape. If the lava is extremely thick, it is capable of building up in the volcano and explode, known as lava domes.
Stay tuned with Byju’s to know more about types of volcanoes, igneous rocks and much more.