Volcanoes

A volcaic eruption takes place when hot ,moltan rock called magma rises up from deep inside the earth and forces its way to the surface.The magma may erupt as a flow of red-hot lava or explode into clouds of ash,rock and dust.

In general volcanoes occur near plate boundaries or under the ocean at plate edges.Hot spot volcanoes however burst through the middle of a plate;they are not related to plate margins.The amount of ash thrown out during an eruption is a good indicator of the size of an eruption.

Types of volcanoes:

Fissure volcano: This type of volcano is a long crack in the crust.Runny lava seeps out along its length and forms a plateau.

Composite Volcano: Cone shaped volcanoes build up from hardening sticky lava.Inside are layers of thick lava and ash from previous eruptions.Gas builds up pressure inside erupts violently.

Shield Volcano: A shield volcano usually has several side vents.The lava is runny and produces gently sloping sides.

Volcano Facts:

The worst volcanic eruption was Mount Tambora,Indonesia which killed 92,000 people in 1815.

Kilauea Hawaii is the most frequently active volcano.