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Friday, 20 July 2012

Volcano : Intro, Formation, Types and Effects

A volcano is a vent or chimney which transfers molten rock known as magma from depth to the Earth's surface. Volcanoes are usually cone shaped mountains or hills. Some volcanoes happen underwater, along the seabed or ocean floor.

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The explosiveness of a volcanic eruption depends on how easily magma can flow and the amount of gas trapped within the magma. Large amounts of water and carbon dioxide are dissolved in magma causing it to behave in a similar way to gas expanding in fizzy drinks, which forms bubbles and escapes after opening. As magma rises quickly through the Earth's crust, gas bubbles form and expand up to 1000 times their original size.

Difference between Magma, Lava & Tephra :
Molten rock is called magma when it is beneath the earth’s surface. When it is erupted and flows through a volcanic vent it is called lava. And when it is erupted explosively as shattered fragments hurled into the air it is called tephra

Types :
Geologists generally group volcanoes into three main kinds.
1. Shield volcanoes

2. Composite volcanoes

3. Cinder cone volcanoes

Positive Effects :
·        It can provide opportunities for generating geothermal energy.
·        It provides valuable nutrients for the soil.
·        It creates very fertile soil which is good for agriculture.

Negative Effects :
·        Many lives can be lost as a result of a volcanic eruption.
·        It can destroy settlements and clear areas of woodland or agriculture.
·        Human and natural landscapes can be destroyed and changed forever.


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