A2 Volcano question - need help please!!Watch this thread
Outline the formation of hot spots and explain their relationship to plate movement (8 marks)
1) A hot spot is the surface expression of a mantle plume (i.e. a volcano sitting above an area of high heat flow).
2) A mantle plume is a stationary area of high heat flow which originates in the mantle below the Earth's crust. The high heat flow causes partial melting of the rocks in the mantle, forming magma (molten rock).
3) When enough magma forms, it pushes upwards through the Earth's crust and forms a volcano (the hot spot).
I'm not entirely sure what the question means by 'relationship to plate movement', but some points you could mention are:
1) Hot spots form in the middle of tectonic plates, as opposed to at the edges of plates where volcanoes are formed at convergent boundaries (where tectonic plates collide with each other) and divergent boundaries (where tectonic plates move away from each other).
2) The age of hot spot volcanoes increases with distance from the mantle plume which formed them. As the plate moves via sea floor spreading (the process by which new oceanic crust is created as magma is erupted along mid-ocean ridges, pushing the plates apart), the current active volcano also moves with the plate, thereby becoming inactive. However, because the mantle plume is stationary, a new active volcano will start to form in place of the previous one.
I hope this helps