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IGCSEs > Geography 🌍 | Tectonic plates πŸ—Ί | > Flashcards

Geography 🌍 | Tectonic plates πŸ—Ί | Flashcards

1
Q

What is a tectonic plate?

A

Rigid sections of rock making up the earth’s crust that meet at plate boundaries where earthquakes, volcanoes, and fold mountains are created.

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2
Q

What is the crust and what does it contain?

A

The thinnest layer of the earth, containing rocks and minerals.

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3
Q

What is the mantle and what does it contain?

A

The thickest layer of the earth, containing solid rock that can flow known as plastic rock.

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4
Q

What is the core and what does it contain?

A

Consisting of the outer liquid core and inner solid core, it contains mostly iron and nickel.

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5
Q

How thick is the crust in km? (on oceans and land)

A

8-40km thick, thinner under oceans.

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6
Q

What are the circular currents in the mantle?

A

Convection currents

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7
Q

Why does the earth have a magnetic field?

A

The outer core creates a magnetic field due to its iron

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8
Q

How old is oceanic crust?

A

Mostly less than 200M years old, as they are created by eruption

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9
Q

How old is continental crust?

A

Older, mostly over 1500M years old

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10
Q

What are the properties of oceanic crust?

A
  • Denser
  • Can subduct
  • Can be renewed and destroyed
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11
Q

What are the properties of continental crust?

A
  • Less dense
  • Cannot subduct
  • Cannot be renewed or destroyed
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12
Q

How do convection currents work?

A

Heated rock from the mantle rises, and cools to fall. This creates a circular current of semi molten rock spreading out and carrying the plate.

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13
Q

Where is the pacific ring of fire?

A

Between the American and Eurasian plate, concentrated with volcanoes. Around the pacific plate.

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14
Q

What is a constructive plate boundary?

A

When two plates are moving apart, forming new land

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15
Q

What is a regular destructive plate boundary?

A

When an oceanic and continental plate boundary move towards each other. The oceanic plate subducts.

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16
Q

What is a conservative plate boundary?

A

When two plates slide alongside each other in different directions

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17
Q

What is a destructive collision plate boundary?

A

When two continental plates move towards each other, creating mountains

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18
Q

What is the lithosphere?

A

The area of solid rock on the earth, consisting of the crust and upper part of the mantle.

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19
Q

What is a subduction zone?

A

Areas where the oceanic lithosphere is recycled to the earth’s mantle at a destructive boundary.

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20
Q

What hazards are found at a conservative plate boundary?

A

Earthquakes because plates slide past each other, locking and eventually releasing their pressure in shockwaves.

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21
Q

What hazards are found at destructive collision plate boundaries?

A

Since the continental crust is of the same density, fold mountains are created. Earthquakes too.

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22
Q

What hazards are found at a constructive plate margin?

A

Creation of shield volcanoes since lava rises, earthquakes, and eruptions

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23
Q

What hazards are found at destructive (oceanic and continental) plate margins?

A

Earthquakes, volcanoes, tsunamis, and creation of a deep ocean trench.

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24
Q

Example of a conservative plate margin

A

Pacific Plate and North American Plate

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25
Q

Example of a destructive collision plate margin

A

Himalayas (Indian and Eurasian plate)

26
Q

Example of a constructive plate margin

A

Iceland (North American and Eurasian plate)

27
Q

Example of a destructive plate margin

A

Indonesia (Australian plate and Eurasian plate)

28
Q

Define crater.

A

A funnel shaped hollow at the top of a volcano

29
Q

Define main vent.

A

The area through which the magma can travel to the surface

30
Q

Define magma chamber

A

A store of molten rock deep inside the earth.

31
Q

What forms the mountain of a volcano?

A

Layers of ash and lava built up from previous eruptions.

32
Q

Define volcanic bombs.

A

Layers of molten rock that solidify as they fall.

33
Q

Define falling ash.

A

Small pieces of shattered rock thrown from the volcano, weighing down buildings.

34
Q

Define secondary cones

A

Openings that form if the main vent of a volcano is blocked and the magma is forced to the surface by another route

35
Q

How does a volcano erupt?

A

Deep within the earth, heat from the core melts rocks to magma. The magma, lighter than the rock around it, forms magma chambers as it rises. Due to being confined in a small area for many years, pressure builds up and magma makes its way up the crust.

36
Q

Why does magma rise?

A

It is less dense than the rock around it.

37
Q

What natural resources draw people to live near volcanoes?

A
  • Fertile soils from ash
  • Rocks for building
  • Mineral deposits are valuable
  • Hot water springs
38
Q

Why don’t people living near volcano’s feel too at risk?

A

Eruptions and earthquakes are uncommon, and better building design and earthquake monitoring makes people feel less at risk.

39
Q

How do areas with faults help those in desert reigons?

A

Fault lines associated with earthquakes allows water supplies to reach the surface.

40
Q

What is the mid-atlantic ridge?

A

A constructive plate margin that stretches through the middle of the Atlantic ocean.

41
Q

What are the 3 Ps?

A

Prediction, protection, planning

42
Q

How effective are we at predicting earthquakes?

A

Ineffective; Scientists have tried seismometers, foreshocks, water pressure changes, but they are not reliable.

43
Q

What is our best way of predicting earthquakes?

A

Studying historical records of earthquakes and identifying high risk areas at plate margins.

44
Q

How can we predict volcanoes?

A
  • Laser beams detecting plate movement
  • Seismometer picking up vibrations
  • Measuring levels of radon gas from earth’s crust
45
Q

How effective is predicting volcanoes?

A

Quite effective, however, we cannot know exactly when it will erupt and LEDCs cannot afford the equipment.

46
Q

How do we protect ourselves from volcanoes?

A

Use earth embankments or explosives to divert lava flows from property. However, the sheer force means little can be done to protect.

47
Q

How can we plan for earthquakes?

A

Produce maps to show the effects of an earthquake and identify areas at risk, or practice earthquake dirlls.

48
Q

How can we protect buildings from earthquakes, above the ground level?

A
  • Weights on roof to counterbalance shaking
  • A steel frame can support the buildings, cross bracing providing extra support to the frame.
  • A counterweight to swing in the opposite direction of the waves
49
Q

How can we plan for earthquakes to stop people from being hurt in buildings?

A
  • Have large open areas for evacuees and emergency services to gather.
  • Have emergency staircases and exits
  • Have a roof to protect pedestrians from being hit by glass.
50
Q

How can we protect a building from earthquakes in the foundation?

A
  • Deep foundation in solid rock

- Shock absorbers in foundation to absorb seismic waves.

51
Q

How can buildings in LEDCs be protected from earthquakes?

A
  • Hollow concrete bricks to cause minimal damage
  • Foundation can be made from stone from destroyed houses
  • Roof can be made from reinforced cement concrete
  • Reinforced steel pillars can provide strength and flexibility
  • Use shock resistant materials like bamboo
52
Q

How can the government regulations help protect us from earthquakes?

A

Enforce planning regulations such as building height limits, and put in extra protection such as hospitals and reservoirs in vital areas.

53
Q

Where does an earthquake start?

A

The β€œfocus”

54
Q

What is the epicentre?

A

The point directly above the focus of an earthquake on the surface.

55
Q

How does an earthquake start?

A

Below the surface where rocks are in great stress, when pressure is at a breaking point it makes a sudden jerking movement that releases seismic waves spreading in concentric circles around the epicentre.

56
Q

What is the Richter scale?

A

A scale from 1-12, where each magnitude number is 10x the energy of the previous

57
Q

What are the categoristics of a composite volcano?

A
  • Destructive plate boundaries
  • Viscious lava
  • Deadlier
  • Volcanic bombs
  • Magma can leak to form secondary cones
58
Q

What are the categoristics of a shield volcano?

A
  • Constructive plate boundaries
  • Flatter
  • Created without great build up of pressure; eruptions more common and less explosive
  • Lava is less acidic and so more runny
  • Created in oceans and peaks can form islands
59
Q

What are examples of composite volcanoes?

A
  • Mayon volcano in Philippines

- Ol doinyo Lengui in Thailand

60
Q

What are examples of Shield volcanoes?

A

Mauna lou in Hawaii, and Kiluea in Hawaii

IGCSEs (68 decks)

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