Page 2 - Microsoft Word - 12.2 VOLCANIC ERUPTION

 Eventually, some of the magma pushes through fissures and vents in the earth’s surface.
 Hence a volcanic eruption occurs and the erupted magma is known as lava.

Why Do Volcanoes Erupt?

 The Earth’s mantle within the crust is classified into different sections depending on
individual seismology.
 The conditions change dramatically from the crust in the mantle location. The pressures
rise drastically and temperatures rise up to 1000 C.
o
 This viscous and molten rock gets collected into large chambers within the Earth’s crust.
 Since magma is lighter than surrounding rock, it floats up towards the surface and seeks
out cracks and weakness in the mantle.
 It finally explodes from the peak point of a volcano after reaching the surface.
 When it is under the surface, the melted rock is known as magma and erupts as ash
when it comes up.

 Rocks, lava and ash are built across the volcanic vent with every eruption

Categories of Volcanoes.
Volcanoes are categorized into three main categories:

 Active

 Dormant
 Extinct
An active volcano is one which is recently erupted and there is a possibility that it may erupt
soon. Examples of active volcanoes are Kilauea in Hawaii, Mount Etna in Italy and Mount
Stromboli also in Italy which has been erupting almost constantly for the last 2000 years.

Mt. Etna(Italy) Kilauea in Hawaii

A dormant volcano is one which has not erupted in a long time but there is a possibility it can
erupt in the future. Examples of dormant volcanoes are Mount Kilimanjaro, Tanzania, Africa and
Mount Fuji in Japan.