Tectonics

Question 1

What is the structure of the earth and properties of each layer ?

Answer 1

1. Crust - thinnest layer (5-70 km),basalt (under oceans) /granite (under land) / broken up pieces of tectonic plates
2. Mantel - thickest layer moving in convectional currents. Semi molten.
3. Outer core - semi liquid iron. Approx 2300km.
4. Inner core - 1250km thick. 5000 celsius. HOTTEST Iron and nickel / dense / 4 x more pressure than the crust

Question 2

Which part of the earth’s structure protects us from harmful solar winds and allows life on our planet ?

Answer 2

Outer core because it is semi liquid iron and acts as a magnetic - earth’s magnetic field

Question 3

What are plate tectonics?

Answer 3

Science behind how plates move making up Earth’s lithosphere

Question 4

What are plate boundaries?

Answer 4

2 or more plates meet / edge where earthquakes/volcanoes occur

Question 5

Who was Alfred Wegener

Answer 5

1912, a geologist Alfred Wegener proposed that all countries were one land mass called Pangaea 200 million years ago. Continental drift theory.

Question 6

What is continental drift ?
Who discovered it?

Answer 6

Continents slowly shifting their positions

Question 7

What is Pangaea?

Answer 7

All continents in one land mass

Question 8

How do the earth’s plates move?

Answer 8

Convection currents in the mantle heat up magma to 5000 celsius. Magma rises to the crust which cools and then sinks to be reheated.

Question 9

How do we know Pangaea existed?

Answer 9

CCFGP

1. Jigsaw fit / pattern (Wegener 1912) - fit together like pieces of a jigsaw puzzle Wegner Theory’s - Continental drift. The continents were once one but drifted apart
2. Convectional currents - magma is heated to 5000 Celsius and then cools and reheats which moves the earths plates
3. Fossil patterns - Similar fossils in continents e.g. Mesosaurus 265 million years ago found in S Africa and S America.
4. Geological patterns e.g. coal was found in Antarctica and coal requires warm climate to form
5. Palaeomagnetism (e.g. Mid Atlantic Ridge in The Atlantic Ocean) every 100 million years the earth’s polarity switches and when it switches the iron particles realign and this causes seafloor spreading

Question 10

What are the major plates globally?

Answer 10

Plate boundaries -
Eurasian
South American
North American
Cocos
Indie Australia
Nazca
Juan de Fuca
Pacific
Antarctic
Juan de Fuca
Caribbean
African

Question 11

What is the subduction zone?

Answer 11

1 plate is forced below another plate, grinding past causing huge amounts of friction and heat

Question 12

How is

Question 13

What is converging / destructive plate boundary?

Answer 13

2 plates move towards each other ie continental + oceanic

Question 14

What are fold mountains?

Answer 14

Mountain ranges formed by 2 plates colliding
(Collision Plate Boundary)

Question 15

What is a oceanic trench?

Answer 15

Deep point in the ocean where continental and oceanic crust drag each downwards

Question 16

What is a composite volcano?

Answer 16

Steep volcano at destructive boundary / magma with high silica (high explosive)

Question 17

What are 3 outputs from convergent/destructive plate boundaries?

Answer 17

composite volcanoes
earthquakes
fold mountains

Question 18

Name the 2 layers bottom part of crust/top part of the mantle?

Answer 18

1. Lithosphere
2. Asthenosphere

Question 19

What are pyroclastic flows?

Answer 19

Currents of hot gas and rock / 450 mph/1000 Celsius

Question 20

What are volcanic bombs?

Answer 20

> 64mm in diameter

Question 21

What are lahars?

Answer 21

mixtures of water, volcanic ash, tephra, rock fragments, and chunks of ice that can flow like wet concrete.

Question 22

What is an earthquake?

Answer 22

Vibrations of Earth’s crust (movement of plate boundaries/major fault lines)

Question 23

Where do most severe earthquakes occur ?

Answer 23

Conservative / divergent
Destructive / convergent

Question 24

What is an epicentre?

Answer 24

Point on the ground above the earthquake

Question 25

What is the focus?

Answer 25

The point in the crust where the earthquake originates

Question 26

What is a fault line?

Answer 26

A line on the earth's surface that traces the geological fault.

Question 27

What are shockwaves?

Answer 27

Shockwaves released from the focus

Question 28

What is stress and release?

Answer 28

Pressure builds between 2 plates and stress is placed on the fault When it builds up too much, it is then released

Question 29

What scale is used to measure magnitude of earthquakes?

Answer 29

Richter scale (how much ground shakes) 0-10

Question 30

What scale is used to measure intensity of earthquake?

Answer 30

Mercalli scale (how much damage) 1-12

Question 31

*** Why was Haiti 2021 earthquake so bad - impact (SEE) and responses?

Answer 31

7.2 Richter Scale and 10km deep IMPACT: SEEP Social - 316,000 died, 1m homeliness, Hospital and schools destroyed; increase in disease Economic - $1.6B damage Environmental -landslides and floods destroyed local ecosystems and habitats RESPONSES: Temporary shelters World Food Programme Temporary hospitals Red Cross and CAFOD sent aid.

Question 32

**** Explain causes and impact of tsunami in an example location

Answer 32

Special waves caused by earthquake Indian Ocean in 2004 Wave was 20 metres high (as high as RC school) As fast as a jumbo jet 500 mph Area affected was = 11 billion football pitches CAUSES: Magnitude of 9 on Richter Scale Epicentre was 30km under pacific ocean Plates moved but got stuck which build up pressure causing earthquake Sea floor was pushed upwards IMPACT Waves reached 12 countries Small islands complete destroyed People were homeless Communication was cut off Electricity was cut off Roads and Railways destryed Fires broke out 250,000 died Disease outbreak Lack of food Lack of jobs

Question 33

How are tsunamis formed?

Answer 33

Usually triggered by earthquakes - tectonic plates move which then triggers displacement of water 800 km/hour..

Question 34

Explain how convection currents move tectonic plates?

Answer 34

Core heats the magma pushing magma up to the earth crust As it cools, magma moves back to core This causes movement in place - diverge/converge

Question 35

Name the 4 types of plate boundaries?

Answer 35

1. Constructive/Divergent 2. Destructive/Convergent 3. Collision 4. Conservative

Question 36

What will occur at a constructive/divergent plate boundary and name an example

Answer 36

Mid-Atlantic, Iceland Under the sea Shield volcanoes (very flat) and earthquakes

Question 37

What will occur at a destructive/convergent plate boundary and name an example

Answer 37

Andes Sea and Land / lots of pressure Cone/Composite volcanoes (very high) and earthquakes

Question 38

What will occur at a collision boundary

Answer 38

Himalayas Continental+Continental towards eachother Fold mountain and Earthquakes

Question 39

What will occur at conservative boundary

Answer 39

San Andreas Fault Continental + Continental slide past eachother Earthquakes

Question 40

*** How can prediction, preparation and protection can reduce tectonic hazards?

Answer 40

Prediction – monitoring volcanoes/earthquakes using gas samples/seismographs/historic eruptions Protection – designing buildings or structures that will withstand natural hazards Preparation – Creating earthquake survival kit / earthquake drills

Question 41

Why was the impact of Haiti's earthquake so bad?

Answer 41

Significant seismic activity Heavily populated Non-existent building regulations