Types of Plate Margins

Question 1

What type of Plate Margins do Earthquakes occur at ?

Answer 1

• Constructive Margins
• Destructive Margins
• Conservative Margins

Question 2

What type of Plate Margins do Volcanoes occur at ?

Answer 2

• Constructive Margins
• Destructive Margins

Question 3

How do Earthquakes and Volcanoes Occur at Constructive Margins ?

Answer 3

1) At a constructive margin plates diverge
2) Mantle is under pressure from the plates above, when they move apart pressure is released at the margin
3) This causes mantle to melt, produces Magma
4) Magma is less dense than the plates so can rise up and erupt to form a Volcano
5) Plates don’t move apart in a uniform way, causes pressure to build up which leads to the plates cracking and creating a fault line causing an Earthquake.

Question 4

What are the 2 different Landforms created at Constructive margins ?

Answer 4

1) Ocean Ridge
2) Rift Valley

Question 5

How does an Ocean Ridge Landform occur at a Constructive Margin ?

Answer 5

• When diverging plates are underwater an ocean ridge forms
• Underwater volcanoes erupt along mid-ocean ridges and they can build above sea level e.g Iceland was formed from the build up of underwater volcanoes along the Mid-Atlantic ridge.

Question 6

Which 2 plates are moving apart at the Mid-Atlantic Ridge?

Answer 6

Eurasion plate and North American plate.

Question 7

How does a Rift Valley occur at a constructive Margin?

Answer 7

• Where plates diverege beneath Land
• Rising magma causes the continental crust to fracture
• Forms fault lines
• Plates continue to move apart
• crust between the parallel faults drop down to form a rift valley.

e.gEast African Rift System stretches from Mozambique to the Red Sea

Question 8

Destructive plate boundaries the 3 plate margins:

Answer 8

Continental-Oceanic
Oceanic-Oceanic
Continental-continental

Question 9

Continental-Oceanic destructive plate margin…

Answer 9

The more dense oceanic plate is subducted beneath the continental plate, this leaves a deep sea trench.

Fold mountains also form where the plates meet, occur when sediment accumulated on the continental crust is pushed up during subduction.

Oceanic crust is melted as it subducts into the asthenosphere. Magma is less dense than the continental crust so will rise above and form volcanoes.

Earthquakes can form during subduction of the plates as they can get stuck and release the pressure in the form of an earthquake.

Question 10

Oceanic-Oceanic destructive plate margin…

Answer 10

• Denser of the 2 will be subducted causing a deep sea trench, earthquake and volcanic eruptions.
• Volcanic eruptions which take place underwater create island arcs, which are a cluster of islands that sit in a curved line e.g the ring of fire.

Question 11

Continental-Continental destructive plate margin…

Answer 11

• Neither are subducted so no volcanoes, but building pressure can cause Earthquakes.
• Fold mountains form when continental crusts converge.

Question 12

Conservative plate margins…

Answer 12

• 2 plates moving past one another
• 2 plates lock together pressure builds up and releases it in the form of an earthquake.

Question 13

What is a Magma plume and the steps of a Magma plume?

Answer 13

Magma plume = vertical column of extra hot magma that rises up from the mantle.

1) Volcanoes form above Magma plumes.
2) Magma plume remains stationary overtime but the crust moves around it
3) Volcanic activity in part of crust above Magma plume decreases as it moves further away.
4) Creates chain islands.