- Plumes of magma assocated with plate movement. Plau,es of magma wear away at the centre of the plate.
- Areas of intense volcanic activity away from the plate margins / concentrations of radioactive elements inside mantle cause hot spot to develop.
- Form plume volcanoes, e.g. Hawaiian Islands, Emperor seamount chan.
1- caused by plume magma (vertical column of magma that rises up from mantle)
2- volcano forms under plate
3- magma plume remains stationary and the crust moves.
4- Plate moves- volcanic activity in area decreases.
5- New volcanoes form above the hot spot
6- chain of volcano forms- the magma plume doesn't move but the crust does, so as the crust moves the plume of magma eats away at different area of plate.
Hot spots cont.
- Hot spot remains in the same place and the plate moves = line of volcanoes.
- Those above hot spot are active, those that are not above the plume are domrant- leaves a chain of extinct volcanoes (evidence of sea-floor spreading).
- Oldest volcanoes put pressure on the crust causing subsidence (sinking into crust again). Subsidence and marine erosion = reduced old volcanoes to Sea mounts.