Composite Volcanoes – Volcanoes that happen on destructive plate margins

To remember the meaning of the term Composite Volcano, use the following mnemonic:

On the compost sit the Vulcans (composite volcanoes) but they quickly run away when there is a violent eruption that destroys plates (destructive plates).

Composite volcanoes occur on destructive plate margins, where the oceanic crust sinks beneath the continental crust (see subduction). Composite volcanoes have these 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