Composite and shield volcanoes are found along plate margins. They have distinctive characteristics and can have both positive and negative effects on people and the landscape.
Volcanoes form when magmaMolten rock that is found within the Earth., which is molten rock from beneath the Earth's crust, reaches the surface. The magma erupts to form lavaMolten rock that is released from the Earth's core in a volcano or fissure. .
Volcanoes usually form along plate marginThe region where two or more tectonic plates meet. It is a zone of intense seismic activity., where crustal plates are either moving towards or away from one another:
constructive plate marginAn area where two tectonic plates are moving away from one another. - this is where two plates move away from one another. Magma rises up to fill the gaps in between.
destructive plate marginWhen two tectonic plates move towards one another. The oceanic crust is forced to sink back into the mantle, whilst the continental crust rises above. Volcanoes and earthquakes are found here. - this is where two plates move towards one another. The oceanic crust sinks beneath continental crust at a subductionWhen one crustal plate is forced beneath the other. zone - a point where one crustal plate is forced beneath another. As the oceanic crust sinks into the mantle it creates magma, which rises to form a volcano.
Volcanoes affect different places in different ways. They cause more damage in poorer countries, where there are fewer resources to predict and prepare for them.