VOLCANO

Among the most powerfull forces of nature that can be found in our earth, the Volcano is a display of an unpredictable natural force. Its name was taken from Vulcano, an island located in the Mediterranean Sea, and given by the ancient Romans because it spewed smoke like vapor, and it was thought to be the home of Vulcan, their god of fire.
A Volcano consists of a fissure in the earth's crust, above which a cone of volcanic material has accumulated (As image below). At the top of the cone is located the crater. The cone is formed by molten or solid matter that flows or is ejected through the vent from inner earth. The study of volcanoes and volcanic phenomena is called volcanology.

The products of volcanoes are molten rocks or magma, solid particles and gases of differents kinds. It is proper to differ the magma of lave, because magma that rises in it is called lave after it flows out at the suface.
The types of eruptions are classified according to the violence level. the types are: Icelandic, Hawaiian, Strombolian, Vulcanian, Pelean and Phreatic (ordered from less violent to the most violent).
Actually, there are a few ways to predict volcanic activity. For example, the most widely used is to study the geogrephic area where the volcano is, because there are always many small earthquake before an eruption. The main problem is that is not very reliable and predictable with much time in advance.
Lately, geologists have joined volcanism into the theory of plate tectonics. that theory says that active volcanoes obtain their energy from the movements of crustal plates(see picture to the right). It is because of this that volcanoes tend to be associated with major plate boundaries.