Explain the origin of Volcanic mountain.

 Q :- Explain the origin of Volcanic mountain. 

Answer :-  

Definition :-   Under the influence of internal forces, the underground semi-liquid viscous magma comes out along the cracks created in a weak part of the crust and accumulates on the surface of the earth over time. It is called a volcano. A volcanic mountain is a type of mountain of accumulation, that is, a mountain that is formed by accumulating volcanic material is called a volcanic mountain.

Examples:-  Fujiyama in Japan, Mauna Loa  in Hawaii (world's highest volcano), Vesuvius in Italy, Barren and Narcondum in India etc.

Origin of volcanic mountain:-

  1. Plate Tectonic Theory :-  

Plates floating on the asthenosphere are always in motion. The plates sometimes move toward each other, sometimes opposite each other and sometimes side by side, resulting in different types of sheet boundaries. Eruptions occur along the border.

(a) Convergent Plate Boundary :- Two plates move towards each other and the heavier sheet descends below the lighter plate. The subducting layer melts into the asthenosphere and causes eruptions.

This is how numerous volcanoes and volcanic mountains have been created along the convergent coastline around the Pacific Ocean.

(b) Parallel Plate Boundary :- Along parallel plate boundary, two plates move away from each other, creating cracks in the earth's crust. Through these cracks, magma from the earth's surface comes out in the form of lava and accumulates to form volcanic mountains.

Thus volcanic mountains such as Madeira, Hekla etc. have been formed under the Atlantic Ocean through eruptions along the Mid Oceanic Ridge located at the border of the parallel plates.

 2. Location of the plume :-

Hotspots are formed as a result of increased radioactive heating deep in the Earth's crust.  From there, magma erupts through upward convection currents of heat.  This upward flow of magma, called a plume, accumulates over time to form a volcano.

 Examples:-  Mauna Loa on the island of Hawaii, Samoa, Tibesti  etc.

3. As a result of strong earthquakes and stress :- 

 When earthquakes and pressures are created, the elasticity of the hot materials inside the earth is lost and liquid rock or magma is formed and hot gases are released.  When the pressure of the gas increases, it escapes through weak points in the surface.  As magma continues to erupt, it piles up around the vent to form volcanic mountains. 

 Examples :- Barren of India, Kilimanjaro of Africa.

   Apart from the above factors, reduction in surface pressure, intrusion of water into the ground,  chemical reactions, earthquakes, heat radiation from the surface etc. also cause eruptions and formation of volcanoes.