VOLCANO (Syllabus: GS Paper 1 – Geography)

Context: A volcano that had rumbled for weeks erupted in southwestern Iceland.

Volcano

• About: A volcano is an opening in the Earth’s crust through which molten rock, hot gases, and other materials erupt.
• Causes: Three predominate causes:

oThe buoyancy of the magma,

oThe pressure from the exsolved gases in the magma,

oThe injection of a new batch of magma into an already filled magma chamber. 

• Classification:

oActive volcanoes have a recent history of eruptions; they are likely to erupt again. 

oDormant volcanoes have not erupted for a very long time but may erupt at a future time.

oExtinct volcanoes are not expected to erupt in the future.

• Main types of volcanoes:

oShield Volcanoes: Low explosivity, basaltic flow. eg- Hawaii volcano

oComposite: They are usually tall with steep even sides and are made out of repeating layers of lava flows. more viscous and cooler lava than basalt, sometimes called stratovolcanoes. eg: Mount Fuji in Japan.

oCaldera: these are most explosive volcanoes, collapses when erupt.

• Distribution Of Volcanoes:

oCircum pacific ring of fire- Most of the volcanoes of earth, active subduction of pacific, Nazca cocos, jaun-de-fuca plate.

oMid Atlantic belt - Along mid Atlantic ridge.

oMid Continental belt- It includes volcanoes of the Alpine mountains and Mediterranean sea.