Tectonic Plates and Plate Boundaries

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Tectonic Plates and Plate Boundaries

The Earth's crust is broken up into tectonic plates. These plates are constantly moving due to convection currents, generated by radioactive decay in the Earth's core.

Earthquakes and volcanoes occur at plate boundaries, the place where two plates meet. There are three different types of plate boundaries; constructive, destructive and conservative.

Destructive plate boundaries

Destructive plate margins form where oceanic crust and continental crust move towards each other, and the oceanic crust is forced underneath the continental crust. This is because the granitic continental plate is much lighter than the basaltic oceanic plate, so it is pushed under forming what is known as an oceanic trench. This is called subduction.

Constructive plate boundaries

A constructive plate boundary is sometimes known as a divergent plate margin, and occurs when plates move apart from each other. Volcanoes are formed by magma pushing up through the gap until it hardens and a new crust is formed.

The majority of creation of new crust occurs under oceans forming ridges and chains of submarine volcanoes. Iceland is an example of a submarine volcano.

Conservative plate boundaries

A conservative plate boundary occurs when two plates slide past each other in different direction, or sometimes going the same direction but different speeds.

Sometimes friction between the two plates can happen as they are moving past each other, and the rocks can catch on each other. When the two plates suddenly release, this causes an earthquake.

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