Types of Volcanoes

Volcano types are determined by a number of factors.  Shape and eruption type are the main deciding elements in determining the type of volcano.  These determine how the volcano will behave, and therefore how it will be classified.

Fissure volcanoes occur when a dike extends to the surface.  When this occurs, large amounts of lava erupt and form flood basalts.

Central volcanoes are the what is commonly of as volcanoes.  Eruptions take place from a single hole in the ground.  The magma is brought up through a pipe like channel, and the volcano erupts onto the surface of the planet.  As eruptions continue, the volcano is build up by accumulation.

Within the category of central volcanoes, there are a few subcategories having to do with whether and how many offshoots there are from the main volcanic channel.

Shield volcanoes are the largest of the central volcanoes.  They erupt effusively, unless water contacts the lava.   They are generally made mostly of cooled lava, have small slopes and in most cases have craters at the top.

Strato-volcanoes, or composite volcanoes, are the most easily recognizable.  They are steep sided and often have a crater at the top.  They are called composite volcanoes because they are composed of alternating layers of lava and cooler cinders or ash.

Cinder cone volcanoes are also steep sided with craters at the top.  However, they have very little lava, and are mostly cinders and ash, as suggested by their name.  They are generally quite small because of this.