Why Do Volcanoes Erupt?

Group One

There are several types of volcanoes and many different reasons for them to erupt. Volcanoes erupt due to pressure and density. Opening a shaken bottle of soda is a good demonstration of eruption. When a volcano erupts, magma rises and bubbles of dissolved gas release through the magma. This causes the magma to explode out of the top of the volcano.

Volcanoes are classified as Active, Dormant, or Extinct.

• Active Volcanoes - currently erupting or have erupted in recorded history
• Dormant Volcanoes - are not currently erupting but are likely to do so
• Extinct(Dead) Volcanoes - have never erupted and are never expected to do so

  There are six types of expolsive volcanoes. They are, from least explosive to most explosive:

• Icelandic
• Strombolian
• Vulcanian
• Palean
• Plinian

With volcanoes, there are three main types. They are mostly named by which they were formed.

Subduction Zone Volcanoes -	These form at the boundaries of two plates, one overriding the other. These are the most violent and destructive. (Ex.- Mt.St.Helens, Mt.Pinatubo, Mt.Vesuvius)
Mid-Ocean Rift Volcanoes -	These form where two oceanic plates are spreading apart. These are more in number than any other type of volcano. They are the world's longest continuous mountain chain, which circles the entire earth (approx. 40,000 miles long).
Hot Spot Volcanoes -	These volcanoes are usually found under the oceanic crust, and the continental crust

The volcano is very dangerous because there is no real way to predict when they are going to erupt, so the ability to warn people about them are less than any other natural disaster.

Sites relating to Volcanoes

Current Eruptions
Volcanoes
Parts of a Volcanoes
Eruption Scale