Plate boundaries - Constructive and conservative plate margins

Question 1

What is the name given to the type of fault at a conservative plate boundary?

Answer 1

Strike-slip fault

Question 2

What direction is the movement in - horizontal or vertical?

Answer 2

either (horizontal or vertical)

Question 3

Why do earthquakes occur on conservative plate boundaries?

Answer 3

1. Lateral movement allows pressure to build up due to friction between the plates.
2. Pressure is released when the plates spring past each other as shock waves.
3. These shock waves cause the ground to shake.

Question 4

What are the characteristics of earthquakes on conservative plate boundaries?

Answer 4

1. Shallow focus (0-70km)
2. can be high in magnitude but mostly moderate

Question 5

What landform is commonly associated with conservative plate boundaries?

Answer 5

The fault line between the two tectonic plates is visible on the earth’s surface.

Question 6

Describe the process of gravitational sliding.

Answer 6

1.As it cools, the lithosphere thickens with distance away from the mid-ocean ridge.
2.The boundary between solid lithosphere and plastic asthenosphere becomes deeper
3. As a consequence, this thickening causes the lithosphere to slope along the asthensophere away from the ridge.

Question 7

Describe the process of ridge push.

Answer 7

1. As magma wells up at mid-ocean ridges, new oceanic crust is formed.
2. The weight of this new crust (increased by gravity) acts upon the lithosphere near the ridge.
3. This pushes the older part of the plate in front.

Question 8

Describe the process of slab pull.

Answer 8

1. The lithosphere sinks into the mantle under its own weight as it cools.
2. The lithosphere then spreads across the asthenosphere and subducts into the mantle.

Question 9

How are rift valleys formed?

Answer 9

1. When two continental crusts are being pulled apart but gravitational sliding (slab pull/ridge push), the lithosphere begins to fracture.
2. This causes faulting to occur and the central part of each valley moves downwards, this part is called a graben.
3. The rocks at the edge of the valley move upwards/ appear to move upwards, these areas of rock that remain are called horsts.

Question 10

What landforms occur at Rift valleys?

Answer 10

1. Grabens
2. Horsts
3. Sheild and composite volcanoes
4. Faulting

Question 11

What hazards occur at a rift valley?

Answer 11

1. Frequent and low magnitude earthquakes
2. Volcanic events

Question 12

Give an example of a rift valley.

Answer 12

Rift valley in North East Africa