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What is a Volcano?
A volcano is a mountain that opens downward to a pool of molten rock below the surface of the earth. When pressure builds up, eruptions occur. Gases and rock shoot up through the opening and spill over or fill the air with lava fragments. 
Types of Volcanoes
1. Active Volcanoes
2. Dormant volcanoes
3. Extinct Volcanoes
Shapes of Volcanoes.
1. Composite Vvolcanoes
2. Spatter Cones
3. Complex volcanoes
4. Cinder Cones
How a Volcano erupts?
An eruption begins when pressure on a magma chamber forces magmaup 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.
What is Lava?
Lava is molten rock that spews from an erupting volcano. It is extremely hot, reaching temperatures as high as 1,300 to 2,000 degrees Fahrenheit (704 to 1093 degrees Celsius). In a volcanic eruption, lava is in liquid form. When it solidifies, it forms igneous rock. However,
Top Five Deadliest volcanoes eruptions?
Rank
Volcano
Year
Deaths
1.
Mount merapi,indonasia
1815
92,000
2.
Sangay,Ecuador
1883
36,417
3.
Stomboli,Italy
1902
29,025
4.
Mount yasur,vanautu
1985
25,000
5.
Mount etna
1792
14,300

Information downloaded from: http://library.thinkquest.org/17457/volcanoes/types.php , http://society.ezinemark.com/five-most-active-volcanoes-in-the-world-7736774e63ab.html and http://www.woodlands-junior.kent.sch.uk/homework/mountains/volcanotypes.html



A volcano is a rupture) on the crust) of a planetary mass object, such as the Earth, which allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface.

Earth's volcanoes occur because the planet's crust is broken into 17 major, rigid tectonic plates that float on a hotter, softer layer in the Earth's mantle.[1] Therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. For example,...

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