Types of volcano

There are two main types of volcano - composite and shield. The two types of volcano form in different places and have very different characteristics.

Composite volcanoes

Composite volcanoes are found on destructive plate margins, where the oceanic crust sinks beneath the continental crust. Composite volcanoes have the following characteristics:

  • Acidic lava, which is very viscous (sticky).
  • Steep sides as the lava doesn't flow very far before it solidifies.
  • Alternate layers of ash and lava. For this reason, they're also known as stratovolcanoes. Strato means layers.
  • Violent eruptions.
  • Longer periods between eruptions.
A composite volcano is made up of layers of ash and lava. It is steep-sided and cone shaped.

An example of a composite volcano is Mount Pinatubo in the Philippines.

Mount Pinatubo is a composite volcano

Shield volcanoes

Shield volcanoes are found on constructive plate margins, where two plates move away from one another. Shield volcanoes have the following characteristics:

  • basic lava, which is non-acidic and very runny
  • gentle sides as the lava flows for long distances before it solidifies
  • no layers, as the volcano just consists of lava
  • less violent eruptions
  • shorter periods between eruptions
A shield volcano is made up of layers of lava. It has a gentle slope and a low, wide cone.
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Mauna Loa is a shield volcano, but was formed over a hot spot, rather than at a constructive plate margin, like other volcanoes.
Mauna Loa is a shield volcano
Mauna Loa is a shield volcano