How Do Volcanoes Form

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                The Earth has evolved across millions of years to its
present form. Volcanoes have historically been natural processes in the
evolution of Earth. Traditionally, in ancient Greek, it was believed that
volcanoes are a supernatural event which connotes the actions of gods and
demigods. Today, human civilization has come a long way in scientifically
analyzing the cause of volcanic eruptions and their formation.<br>A
volcano is a fissure in the earth's top layer which allows the hot magma
from the bowels of the earth to break through to the surface. The
etymology of the word is drawn from the name of Vulcan, the roman god of
fire. <br>The earth's core is a mass of hot molten rock called the magma.
It is normally lighter than the rocks surrounding it. Over a period of
time, the magma gets built up and seeks to find out the weak layers on
the strata to come to the surface. When it reaches a weak surface, it
bursts through and spews a huge amount of molten rock, volcanic gases and
ash. This is the essential feature of most of the volcanoes which are
found in the world, especially those that are located in the Pacific Rim,
metaphorically known as the ring of fire.<br>A volcano is typically
formed through the movement of tectonic plates on earth. As these plates
move towards or away from each other, they cause weak spots for the
earth's hot mantle to seep through. The molten hot mantle in fact, also
melts down the hard rock on one or more tectonic plates. As the pressure
of this mantle reaches its peak, it gets released through any nearby
opening.<br>Most of the volcanoes are typically thought of as erupting
from active volcanic mountains. An interesting fact is that they may also
be released through any opening on the surface or through a sub-oceanic
fissure. The amount of ash and other material released through the
fissure would depend on the inherent pressure built up by the magma
before it gets released.<br>Different types of volcanoes are unique in
terms of the location where they occur. Some are sub-glacial volcanoes
which are found in cold glaciers. Other types of volcanoes are submarine
volcanoes, in which the lava comes out under the sea.<br>Volcanic
activity is not unique to planet earth alone. There are several active
volcanoes which have been reported across the planets in our solar
system. They occur in planets like Venus and Mars. They have also been
known to exist in some satellites of large planets like Jupiter.<br><br>

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