Constructive margins

Question 1

When does a constructive margin occur?

Answer 1

When two plates are moving apart (diverging)

Question 2

How do constructive margins form volcanoes? 3

Answer 2

Mantle is under pressure from the plates above. When they move apart the pressure is released at the margin.
The release of pressure causes the mantle to melt, producing magma.
The magma is less dense than the plate above, so it rises and erupts to form a volcano

Question 3

How do constructive margins cause earthquakes? 3

Answer 3

Plates don’t move apart in a uniform way. This causes pressure to build up.
When the pressure becomes too much the plate cracks, making a fault line and causing an earthquake.
Further earthquakes may also occur along the fault line once it’s been created