The volcanic eruptions are oozing out of magma from the earth core. What is magma? What causes it to explode? What are the factors responsible for volcanic eruptions? Magma is formed by the melting of earth’s upper mantle and lower mantle. During the volcanic eruptions the magma contains some dissolved gasses. Volcano is nothing but the opening or crack through which this magma flows out. This volcano eruption occurs due to three main reasons: pressure from the gasses dissolved in magma, the buoyance of the magma and entry or collection of more and more magma in the existing region.
How exactly does this eruption happen?
The rock inside the earth melts and its melted mass is the same and its volume increases. This melted rock is nothing but the magma. The melted rock has lesser density than the surrounding rocks. The magma rises to the surface due to its buoyance force. The density of the magma is less than its surroundings and the magma rises to the surface and erupts. These volcanic eruptions are caused by the earth quakes too. When there is earth quake the magma builds up a lot of pressure from inside and erupts due to high pressure conditions. Frequent studies proved that the super volcanos have around 500 cubic km of the erupted magma.
Researches show that the amount of dissolved gasses in the magma are less but increases with the increase in pressure. Magma contains volatiles such as water, carbon dioxide and sulphuric dioxide dissolved in the magma. Studies have shown that the magma chamber is big in size and it is also responsible for the super volcanic eruptions. More the size of the magma chamber more is the collection of magma and thus there is more pressure built up and the buoyance is high resulting in the eruption. The increase in magma chamber effects the stability of the rock in chambers.
Volcanic eruptions are like remarkable sight. There is a red hot chunk of hot mass exploding from the top of the surface of vent. There is a crater which appears on the top of the vent. And the whole volcanic mass lies under this crater. The magma erupts through the central vent. Though pressure is one of the parameter for the volcanic eruption it always does not account for this. There is no much evidences for the pressurised magmatic eruption. But most of the time it’s the buoyance which causes these super volcanic eruptions.
There is decrease in the solubility of water in magma as the magma moves towards the surface. There is more and more water exsolves from the magma as it moves towards the surface. Thus it in turn increases the gas to magma ratio. The injection of magma to the existing magma content increases the density which triggers the volcanic eruption. Though all these factors are well known to volcanologists, it sometimes becomes tough to predict the reason behind sudden volcanic erruptions.