earthquakes/volcanoes

• The Earth's surface is made up of two types of crust: oceanic crust and continental crust
• Oceanic crust


  The surface of the Earth's crust found underneath the oceans, forming the ocean floor. It is denser than the continental crust and can be subducted.
• Continental crust


  The surface of the Earth's crust found underneath large land masses. It is generally older than oceanic crust and is less often destroyed.
• Earthquakes are found along all types of plate boundaries (or margins)
• Volcanoes are also mainly formed at plate boundaries
• There are some important exceptions, for example the Hawaiian Islands, which are entirely volcanic in origin, formed in the middle of the Pacific Ocean, more than 3,200km from the nearest plate boundary
• Hotspot theory


  There are fixed spots in the mantle where magma rises to the surface. As the crust moves over these fixed spots, volcanoes are created, eventually forming a chain of volcanoes.