CONCEPTS in Action

Types of Volcanoes

Volcanoes have different types of magma. The viscosity of the magma plays a large part in determining a volcano's ultimate shape and appearance.

Volcanoes most commonly occur at three major locations on Earth—mid-ocean ridges, subduction zones, and hot spots. Each type of volcanic region produces a different kind of volcano because of the type of magma that exists there. The three main types of volcano are shield volcanoes, composite volcanoes, and cinder cones. Most volcanoes that form above subduction zones, for example, are composite volcanoes. In contrast, many volcanoes that form above hot spots are shield volcanoes.

Shapes of Volcanoes

Each type of volcano has a different shape. The shape is determined by the kind of lava, ash, and cinders that erupt from the volcano's vent, and especially the viscosity of the lava.

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