1.7 Causes of Volcanoes

Question 1

formation of volcanoes on constructive plate boundaries

Answer 1

When two plates move apart, a rift in the earth’s crust is formed. Molten rock (magma) rises from the mantle towards the crust. ​​Magma builds up , cools and forms a volcano.

Question 2

formation of volcanoes in Destructive Plate Boundaries​

Answer 2

when oceanic plate subducts under the continental, due to its higher density, it melts because of the heat produced in the mantle releasing carbon gas. The gas released forces it’s way to the surface dragging magma with it and is released in a volcanic eruption (this forms a violent composite volcano). ​

Question 3

formation of hot spots

Answer 3

A hotspot is formed when a mantle plume rises from deep within the Earth and melts through the tectonic plate above it(because the crust above the plume was weak), creating a volcanic island. Over time, as the tectonic plate moves, the volcanic activity creates a chain of islands. This process continues until the mantle plume is no longer active.