What Is a Volcano
The term, ‘Volcano’ is derived from’ Vulcan’, the ‘God of fire’, as per Roman mythology. Volcano refers to an opening in the earth’s surface through which molten material at very high temperature oozes out at high pressure. Volcanoes are classified into different categories based on their shape and the frequency of their eruption. Volcanoes are mainly the results of interaction between the tectonic plates and are formed at the convergent or divergent boundaries. On the other hand, hotspots are the kind of volcanoes that are formed by the ‘mantle plumes’ which rise above the core-mantle boundary. It would be worth noting here that most volcanoes that erupt far from the plate boundaries are explained as hotspots.
Depending on the shape of the volcano, the two main types of volcanoes are the shield volcanoes and the stratovolcanoes. The stratovolcanoes are the most common form of volcanoes and they are conical in shape. Main parts of this volcano are magma chamber, conduit, vent and crater. The stratovolcanoes or the composite volcanoes are the most dangerous forms of volcano as they spit out large amounts of lava, ash and cinder that can jeopardize the life of people in neighboring areas. Owing to the great height of these volcanoes and the high inclination of their slopes, the lava formed, flows down and poses a great threat to population in the vicinity. Shield volcanoes on the other hand have low viscous lava that does not explode with high pressure and the volcano derives its name from the shape of it’s that resembles a shield. These kinds of volcanoes are more common in areas near the coast.
Based on the frequency of volcanic eruption, the volcanoes can be classified under three heads, namely, active volcanoes, extinct and dormant volcanoes. As the name suggests, active volcanoes are the ones that erupt very frequently and show signs of possible eruptions in the near future. The extinct volcanoes are the ones that have erupted in the past but have remained inactive for a very long period of time, thereby, completely nullifying the chances of them erupting ever again. The volcanoes that have remained silent for long periods of time; but have supply of molten material and lie in the seismic regions are termed as dormant volcanoes. It is to be noted here that such classification is not easy to be done as the lifespan of a volcano cannot be predicted with precision.
A volcanic eruption can lead to catastrophes owing to the molten magma that burns down everything on its way. The ash and the poisonous gases from volcanoes tend to disrupt the weather in the region and pose various health hazards in the neighboring regions.