Hazards - Tectonic plates

Question 1

What are the layers of the earth? (4)

Answer 1

1 - Inner core

2 - Outer core

3 - Mantle - asthenosphere + Lithosphere

4 - Crust - continental + oceanic

Question 2

Describe the inner core?

Answer 2

A solid ball containing iron and Nickel

Question 3

Describe the outer core?

Answer 3

Is semi-molten and contains Iron and Nickel

Question 4

Describe the mantel?

Answer 4

Mostly made of Silicate rocks

Question 5

Describe the lithosphere? (3)

Answer 5

1 - Is the crust and the uppermost mantle

2 - This constitutes the hard and ridged outer layer of the earth

3 - It is the layer which is split into a number of tectonic plates.

Question 6

Describe the asthenosphere? (2)

Answer 6

1 - That part of the mantle which lies directly beneath the lithosphere

2 - Is semi - molten

Question 7

What is happening at a constructive plate margin?

Answer 7

The plates are moving apart/diverging

Question 8

What occurs at constructive plate margins?

Answer 8

1 - Earthquakes

2 - Volcanoes

Question 9

What landfroms are created a constructive plate margins? (2)

Answer 9

1 - Ocean ridge

2 - Ridge valley

Question 10

What is happening at destructive plate margins?

Answer 10

Plates are moving towards each other (converging)

Question 11

What occurs at destructive plate margins?

Answer 11

1 - Volcanoes

2 - Eathquakes

Question 12

What are the three types of destructives margins?

Answer 12

1 - Oceanic-Continental

2 - Oceanic-Oceanic

3 - Continental-Continental

Question 13

What three landforms occur at destructive plate margins?

Answer 13

Oceanic - Continental = Deep sea trench + fold mountains

Oceanic - Oceanic = Deep sea trench + Island arcs

Continental - Continental = Fold mountains

Question 14

What happens at conservative plate margin?

Answer 14

Plates are sliding past one another

Question 15

What occur at conservative plate margins?

Answer 15

Earthquakes

Question 16

What landform is created at conservative plate margins, giving a named example?

Answer 16

1 - Fault lines

2 - e.g San Andreas Fault in California.

Question 17

Compare the continental and oceanic crust?

Answer 17

Continental crust is thicker

Question 18

What is the average temperature of the inner core?

Answer 18

6000⁰c

Question 19

What is the average temperature of the mantel?

Answer 19

1000-3500⁰c

Question 20

What are the earths sources of internal energy? (3)

Answer 20

1 - Heat from inner core + mantel

2 - Heat energy left over from the earths formation

3 - Radioactive decay of elements

Question 21

What are plate margins/boundaries?

Answer 21

The places where the plates meet

Question 22

What is the theory of plate tectonics?

Answer 22

The earths lithosphere is made up of plates that move

Question 23

What is the theroy of convection currents? (4)

Answer 23

1 - lower parts of the asthenosphere, closer to the core, heat up, becomes less dense and slowly rises

2 - As they move towards the top of the asthenosphere they cool down, become more dense and slowly sink

3 - The circular movement of this semi-molten rock are called convection currents

4 - They create a drag on the base of the tectonic plates - causing them to move

Question 24

What is the theory of slab pull? (2)

Answer 24

1 - At destructive plate margins, denser crust is subducted under less dense crust

2- The sinking of the denser plates edge pulls the rest of the plate towards the boundary

Question 25

What is the theory of ridge push/ gravitational sliding?(4)

Answer 25

1 - At constructive plate margins, hot magma rises to the surface and forms new crust 2 - The hot magma heats the surrounding rock which expands and rises above the surface of the surroudning crust forming a slope 3 - The new crust cools and becomes denser. Gravity causes the dense rock to slide downslope, away from the margin 4 - This puts pressure on the tectonic plates, causing them to move apart

Question 26

What is sea floor spreading? (3)

Answer 26

1 - When tectonic plates diverge, magma rises to fill the gap, cools and forms new crust 2 - Over time the new crust is dragged apart and new crust forms between it 3 - If this occurs under the sea at a plate margin, the sea floor gets wider

Question 27

How doe volcanoes and earthquakes occur at constructive plate margins? (3)(2)

Answer 27

**Volcanoes:** 1 - The mantel is under pressure from the above plates 2 - when they diverge the pressure is released, causing the mantel to melt, producing magama 3 - Magma is less dense than the plate above so rises and erupys to form a volcanoe **Earthquakes:** 1 - When the plates diverge, some parts move faster than others causing pressure to build up 2 - This causes the plate to crack, making a fault line and causing an earthquake

Question 28

How are ocean ridges formed at constructive margins, giving a named exmaple? (2)

Answer 28

1 - When plates diverge underwater E.g **Mid-Atlantic ridge** formed where **Eurasian** and **North** **American** plate are diverging 2 - Underwater volcanoes can erupt along mid-ocean ridges and can build up to be above sea level E.g **Iceland** formed by the build up of underwater volacnoes along the **Mid-Atlantic ridge**

Question 29

How are rift valleys formed at constructive plate margins, named examples ? (3)

Answer 29

1 - When plates divereg beneath land, magma rises and causes the continental crust to bulge and fracture, forming fualt lines 2 - As the plates continue to diverge, the crust between parralell fault lines drops down to form a rift valley E.g **East African** rift system formed from **Nubian** and **Somalian** plates are diverging 3 - Volacnoes are found around rift valleys E.g **Mount Kilimangaro** is a volcanoe in the **East African** rift system

Question 30

How do deep sea trenches and fold mountains form at Oceanic-Continental plate margins, named examples?

Answer 30

**Deep sea trench:** 1 - Dense oceanic crust is subducted under the lighter continental crust E.g Peru-Chile trench In Pacific **Fold mountains:** 1 - When sediment accumulates on the continental crust the edge of the crust and the sediment is folded upwards

Question 31

How are Volacnoes and Eathquakes formed at oceanic-continental plate margins? (2)(2)

Answer 31

**Volcanoes:** 1 - The oceanic crust is melted by friction into magma 2 - The magma is less dense than the continental crust above so rises to the surface forming volcanoes **Earthquakes:** 1 - When plates get stuck this can causes pressure to build up 2 - This can cause plates to jerk past eachother causing an earthquake

Question 32

How are Island arcs and deep sea trenches formed at Oceanic-Oceanic plate margins, named example? (2)

Answer 32

**Deep sea trench:** 1 - Denser of the two plates will subduct 2 - This triggers earthquakes and volacnic eruptions **Island arcs** 1 - Formed by volacanic eruptions underwater E.g Mariana Islands

Question 33

How are fold mountains and earthquakes formed at Continental - Continetal margins, named example?

Answer 33

1 - When continental crust converges E.g Himalayas 2 - Pressure that builds up between contiental crust can cause earthquakes

Question 34

How are earthquakes formed at Conservative plate margins, names example? (3)

Answer 34

1 - Plates get locked together in places and pressure build up 2 - This causes the plates to jerk past eachother and crack to from fault line 3 - The energy is released as an earthquake E.g Many earthquakes occur along Sand Andreas fault line

Question 35

How do magma plumes form a chain of volacnoes, named example? (6)

Answer 35

1 - A magma plume is a column of very hot magma that rises from the mantel 2 - Volacanoes form above magma plumes 3 - The crust above the magma plume moves 4 - Volacanic activity in the part of the crust that was above the plume decreases as it moves away from the plume 5 - New volacnoes form in the part of the crust that is now above the magma plume 6 - As the crust continues to move a chain of volacnoes are formed E.g Hawaii formed by magma plumes