A volcano can be simply defined as a rupture or an opening on the crust of a planet like earth. This opening allows hot ash, molten rock and gases to blow off from the underground spaces. Volcanoes generally acquire shape of a mountain. Volcanoes are usually found at places where tectonic plates get converged or diverged. But there existence at a particular place depends upon many environmental and geological factors. Volcanoes can also occur at a place because of hot spots or mantle plumes. Even hotspot volcanoes are very common at other planets of solar system especially on moons and rock based planets.
An eruption begins when pressure on a magma chamber forces magma up through the conduit and out the volcano's vents. When the magma chamber has been completely filled, the type of eruption partly depends on the amount of gases and silica in the magma. The amount ofsilica determines how sticky (level of viscosity) the magma is and water provides the explosive potential of steam.
When magma reaches earth's surface it is called lava. It may pour out in gentle streams called lava flows or erupt violently into the air. Rocks ripped loose from the inside of the volcano or torn apart by the gas may be shot into the air with the lava. These rocks blown out of a volcano are called pyroclastic rocks.
Volcanic activity is classified by how often a volcano erupts. A volcano may be active, intermittent, dormant, or extinct. Active volcanoes erupt constantly. Intermittent volcanoes erupt fairly regularly. Dormant volcanoes are inactive, but not long enough to determine whether they will erupt again or not. Extinct volcanoes have been inactive since the beginning of recorded history.
this is the video of volcanic eruption,. watch and enjoy
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