3.1.5.2 Plate Tectonics 2

Question 1

3 types of plate margins

Answer 1

Destructive (convergent)
Constructive (divergent)
Conservative

Question 2

What are the 3 types of destructive (convergent) plate margins

Answer 2

Oceanic + continental -> subduction
Oceanic + oceanic -> subduction
Continental + continental -> collision

Question 3

What happens at a destructive margin

Answer 3

2 plates collide (converge)

Question 4

Describe what happens when oceanic plate meets continental plate (subduction)

Answer 4

• Oceanic plate is denser + subducts under continental plate
• continental plate is lighter + less dense
• friction + melting occurs between 100km+700km deep where oceanic plate is melted -> Magma is formed and rises as it’s less dense than crust

Question 5

What’s the zone called where friction + melting occurs in subduction

Answer 5

Benioff zone

Question 6

2 landforms created when oceanic meets continental (destructive)

Answer 6

Ocean trenches - oceanic plate bends

Fold mountains - continental land mass uplifted,compressed + folded

Question 7

2 hazards when oceanic meets continental (destructive)

Answer 7

• intermediate + deep focus earthquakes

- explosive volcanoes

Question 8

Why do earthquakes occur

Answer 8

Due to the tension being released

Question 9

Describe what happens when 2 oceanic plates meet (destructive subduction)

Answer 9

When they collide, 1 plate (faster/denser) subducts beneath the other, there is melting in the Benioff zone and magma rises

Question 10

2 landforms formed when 2 oceanic plates meet (destructive subduction)

Answer 10

• ocean trenches

- island arcs

Question 11

2 hazards when 2 oceanic plates meet (destructive subduction)

Answer 11

• deep focus earthquakes

- explosive acid volcanoes

Question 12

Describe what happens when 2 continental plates meet (destructive collision)

Answer 12

Colliding plates + anything deposited between then get u-lifted + buckle (high fold mountains) - both plates are buoyant

Question 13

2 landforms formed when 2 continental plates meet (destructive collision)

Answer 13

• fold mountains

- Nappe

Question 14

Example or fold mountains

Answer 14

The Himalayas

Question 15

What’s nappe

Answer 15

A large body/sheet of rock moved about 2km

Question 16

What’s the main hazard created from 2 continental plates meeting (destructive collision)

Answer 16

Shallow focus earthquakes -> tension from crust being strained

Question 17

What happens at constructive (divergent) plate margins

Answer 17

2 plates separate

Question 18

What divergence happens in oceanic areas

Answer 18

Sea-floor spreading on either side of mid-oceanic ridge e.g mid-Atlantic ridge

Question 19

What divergence happens in continental areas

Answer 19

Stretching + collapsing of crust forming rift valleys e.g Great African Rift Valley

Question 20

What plate margins would you find some of the youngest rocks on earth
Why

Answer 20

Constructive (divergent)

As new crust is being formed as the gap created by spreading plates is filled by magma rising from the asthenosphere
As the magma cools, it solidifies to form new,dense basaltic rock

Question 21

Describe what happens at conservative plate margins
What hazard occurs

E.g of conservative plate margin

Answer 21

2 plates slide past each other in opposite directions/at different speeds
As this happens, stress builds as the plates snag + grind on each other, causing earthquakes

E.g Haiti, San Andreas fault