A volcano is an opening, or rupture, in a planet's surface or crust, which allows hot magma, volcanic ash and gases to escape from below the surface.
Volcanoes are generally found where tectonic plates are diverging or converging. A mid-oceanic ridge, for example the Mid-Atlantic Ridge, has examples of volcanoes caused by divergent tectonic plates pulling apart; the Pacific Ring of Fire has examples of volcanoes caused by convergent tectonic plates coming together.
The explosiveness of a volcanic eruption depends on how easily magma canflow and the amount of gas trapped in it. Large amounts of water and carbondioxide are dissolved in magma. They behave like gas in fizzy drinks. Afteropening the bottle the gas expands, forming bubbles that escape. This alsohappens when magma rises quickly through the crust - gas bubbles form andexpand up to 1000 times their original size.
There are many different types of Volcano, which are Fissure vents, Shield volcanoes, Lava domes, Cryptodomes, Volcanic cones (cinder cones), Stratovolcanoes (composite volcanoes), Supervolcanoes, Submarine volcanoes, Subglacial volcanoes, Mud volcanoes, and Lava texture.Effects of volcanoes
There are many different types of volcanic eruptions and associated activity: phreatic eruptions (steam-generated eruptions), explosive eruption of high-silica lava (e.g., rhyolite), effusive eruption of low-silica lava (e.g., basalt), pyroclastic flows, lahars (debris flow) and carbon dioxide emission. All of these activities can pose a hazard to humans. Earthquakes, hot springs, fumaroles, mud pots and geysers often accompany volcanic activity.
Volcanic Eruption...
References:
- http://en.wikipedia.org/wiki/Volcano
- http://www.nationalgeographic.com
- http://youtube.com
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