Volcano Eruptions

The form of the volcano depends on the minerals contained in the magma. The shape of a volcano is created by the violence of the explosion and the amount of water present in the magma.

• A shield volcano has a form that is large with low sloping sides and a broad summit area. This type of volcano is caused by a slow lava flow that has a basaltic composition. The island of Hawaii (the main island) is a great example of a shield volcano.

• A cinder cone volcano is a mound that is formed by flowing gases that are responsible for shooting blobs and ribbons of lava into the air. As the lava comes down, it hardens before touching the ground. When the pressure drops, the final stage of the building of a cinder cone volcano is when some lava flows through the base of the cone. The longer it takes for the volcano to erupt, the bigger the cone. Some sizes vary between a few meters to over 610 meters high. A good example is the Paricutin volcano in Mexico which after erupting regularly between 1943 and 1952 has been responsible for the destruction of the village.

• A composite volcano is the result of several eruptions, sometimes happening after a period of a hundred years to a hundred thousand years. This form has a cycle of quiet and explosive eruptions of lava. The lava covers the debris with a shell that is resistant to erosion. This shell is responsible for the formation of the strong and steep sides of this type of volcano.

# posted by kevin : 8:55 PM