Volcanoes – An Introduction


Volcanos are the rupture or opening in the crust or surface of a planet which allows volcanic ash, hot magma, and gases to escape from the inner part of the planet.

Volcanoes-Where to be found?

The volcanos are commonly found in places where the tectonic plates are converging or diverging. As a contrast, the volcanoes are not created in such places where two tectonic plates slide past each other. Volcanoes can also be formed in such places where the thinning and stretching process of the crust part of the Earth happens in the interior parts of the plates. Volcanism which happens away from the plate boundaries is considered as the mantle plumes.

Effect of volcanism:

When the volcanoes erupt, it results in various hazards along with the immediate vicinity. The volcanic ash is a threat to the aircraft, as the volcanic ash gets melted by the high temperature of the jet engines. Besides, large volcanic eruptions can also affect the temperature as the sulfuric acid droplets and volcanic ash obscure the sun and also reduces the temperature of the troposphere or the lower part of the Earth’s atmosphere. This effect of volcanism is named as the volcanic winters and it results in the catastrophic famines.

Features of the Volcanoes:

The common perception of the volcano is a conical shaped mountain, poisonous gases and spewing lava. But the features of the volcanoes or the volcanic ranges are different and complicated. The behavior, as well as the structure of the volcanoes, depending on various factors like rugged peaks, vents of the volcano, magmatic gases and much more.

Types of the volcanoes:

Volcanos can be of three types. Such as Active volcanos, Extinct volcanoes, and Dormant volcanos.

Active volcano: Active volcanos are those which erupts on a regular basis

Extinct volcano: Volcanos, which used to erupt in historical times but are quiet now, is known as the Extinct volcanos.

Dormant volcano: The volcanos which have not erupted since the historical times are known as the Dormant volcanos.

Another way to classify the volcanoes is by the composition of the erupted materials or lava. The lava can be classified into four categories. Such as:

  •      If the lava or the erupted magma include a high percentage of silica. This lava is known as the felsic. This type of lava is highly viscous and it erupts as stubby flows or domes. It contains more than 63% Silica.
  •     If the magma contains 52-63% silica, the lava is known as the intermediate composition of lava. This type of lava generally comes out of the andesitic volcanoes.
  •     The erupted magma which contains 45-52% silica, is known as Mafic.
  •    Lastly, some magmas contain less than 45% silica. This lava is known as the ultramafic lava.


Source by Benny