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GCSE Geography > The restless earth > Flashcards

The restless earth Flashcards

1
Q

What are the four layers of the earth?

A

Inner core, outer core, mantle, lithosphere/crust

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2
Q

What is the crust/lithosphere divided into?

A

Tectonic plates

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3
Q

Why do the tectonic plates move?

A

Due to convection currents in the mantle they float on

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4
Q

What is a constructive plate margin?

A

Where two tectonic plates are moving apart; causing cracks in the crust where a gap is forming; magma rises up into cracks to form new crust

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5
Q

What hazards are found at constructive plate margins?

A

Volcanoes and earthquakes

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6
Q

What is a destructive-subductive plate margin?

A

Where and oceanic plate is forced underneath a continental plate; the oceanic plate is destroyed as is it melts to form magma

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7
Q

What hazards are found at destructive-subductive plate margins?

A

Volcanoes and earthquakes

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8
Q

What is a destructive-collision plate margin?

A

Where two continental plates move towards each other and collide.

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9
Q

What hazards occur at destructive-collision plate boundaries?

A

Earthquakes

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10
Q

What is a conservative plate margin?

A

Where two plates slide past each other; they move at different angles and speeds- causing sticking

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11
Q

What hazards occur at conservative plate margins?

A

Earthquakes

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12
Q

What are the characteristics of oceanic crust?

A

Newer (most less than 200 million years old) , thinner (5-10 km thick), denser (more basalt in it), can sink, can be renewed and destroyed

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13
Q

What are the characteristics of continental crust?

A

Older (most over 1500 mil yrs old), thicker (20-70 km), less dense (more granite in it), cannot sink, cannot be renewed or destroyed

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14
Q

What is the difference between the focus and the epicentre?

A

The focus: where the pressure build up has occurred (underground) between the plates
The epicentre: point on the crust directly above the focus, from which seismic waves radiate out

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15
Q

What is a seismograph?

A

The machine that measures the size/magnitude of the waves

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16
Q

When did the Haiti earthquake occur?

A

12th January 2010

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17
Q

What % of people in Haiti live in poverty and what % have access to clean water? (pre-earthquake)

A

80% of Haitian people lie in poverty

46% have access to clean water (not even half)

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18
Q

Where is Haiti?

A

An island in the Caribbean, (half of the island is the Dominican republic); it is found in the South American continent

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19
Q

What is the average life expectancy in Haiti? how many people per doctor?

A

Average life expectancy: 62 yrs old (1/2 pop. under 18)

People per doctor: 1000 people per 0.25 doctors

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20
Q

Where was the epicentre and focus of the Haiti earthquake?

A

Epicentre: 25 km from Haitian capital Port-au-Prince
Focus: only 13 km underground

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21
Q

What were 4 direct impacts of the earthquake in Haiti?

A

34/37 of doctors in Port-au-prince were killed, 1/3 buildings destroyed, 300,000 people left homeless, 230,000 (approx.) killed directly

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22
Q

What were 4 indirect impacts of the earthquake in Haiti?

A

5 years later people still living in tents in capital, Nov. 2010 cholera outbreaks, over 300,000 killed by cholera, only 2% of $1 million relief funds raised for Haiti released, Haitian tourism decline

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23
Q

What were 3 short term responses of the Haiti earthquake?

A

3/4 damaged buildings inspected and repaired, 200,000 received food or cash for public work (e.g. clearing rubble), 2000+ helped by Dominican republic emergency team

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24
Q

What were 2 long term responses of the Haiti earthquake?

A

World bank pledged $100 mil to support reconstruction/recovery programmes, red cross & UN remained in Haiti to help- stayed for 2 yrs & built long term shelters

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25
Q

When did the Japan earthquake begin?

A

11th March 2011

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26
Q

What was the rating of the Japan earthquake?

A

The earthquake was a 9 on the Richter scale

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27
Q

How strong was the Japan earthquake?

A

It was the force of 2 million Hiroshima bombings happening simultaneously

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28
Q

Where was the focus of the Japan earthquake?

A

Only 30 km underground

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29
Q

Where was the epicentre of the Japan earthquake?

A

130 km away from the city of Sendai

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30
Q

What physically happened to Japan as a country when the earthquake struck?

A

The whole of Japan shifted 3 m out to sea, and parts of the coast sunk over 1 m

31
Q

What were 4 direct impacts of the Japan earthquake?

A

Gas and oil lines ruptured- causing fires, liquification, 350 km away in Tokyo buildings shook for 5 minutes, railways buckled (transport impossible)

32
Q

What were 3 secondary impacts of the Japan earthquake?

A

Tsunami, Fukishima nuclear power plant flooded, over 500 aftershocks (over 7 exceeded 7.2 on Richter scale)

33
Q

How many people were killed by the Japan tsunami?

A

19,000 to 20,000 people

34
Q

How fast was the Japan tsunami travelling?

A

800 km/h with a 100 km wavelength

35
Q

What kind of plate boundary is Japan on?

A

A stick-slip fault boundary

36
Q

What are the steps to attempt to reduce the impacts of earthquakes?

A

Protect, prepare, predict

37
Q

What does the ‘protect’ stand for (in terms of earthquake impact reduction)?

A

Constructing buildings so they are safe to live in and will not collapse

38
Q

What does the ‘prepare’ stand for (in terms of earthquake impact reduction)?

A

Organising activities/drills so that people know what to do if an earthquake happens

39
Q

What does the ‘predict’ stand for (in terms of earthquake impact reduction)?

A

Attempts to forecast an event- where it will happen- bases on current knowledge

40
Q

Where are ocean trenches formed?

A

On destructive-subductive plate boundaries

41
Q

Where are fold mountains formed?

A

On destructive-subductive and destructive-collision boundaries

42
Q

How are fold mountains formed?

A

Geosyncline (depression between plates)under sea, fills with sediment from rivers, sediment compressed to rock, plates move together-sediment folds

43
Q

What are 3 reasons that people live close to volcanoes?

A

The soil is fertile from ash and lava, they are tourist attractions, they are a source of geothermal energy

44
Q

Where are the world’s most active volcanoes found?

A

At the edge of plate margins- specifically the ‘pacific ring of fire’

45
Q

What are the two main types of volcano?

A

Composite and shield volcanoes

46
Q

What are the characteristics of shield volcanoes?

A

Gentle sloping sides, usually non-violent, caused by eruptions of ‘basic lava’

47
Q

What are the characteristics of composite volcanoes?

A

Steep-sided, symmetrical, narrow base, acid lava, lava cools quickly, often explosive eruptions

48
Q

Why do composite volcanoes have explosive eruptions?

A

Lave cools quickly, so can plug the vent, causing pressure build-up and explosive eruptions (more pressure is released)

49
Q

Where are composite volcanoes usually formed?

A

Destructive subductive plate boundaries

50
Q

Where are shield volcanoes usually formed?

A

Constructive plate boundaries

51
Q

How are volcanoes formed at destructive-subductive boundaries?

A

Oceanic plate subducts, part of oceanic melts into magma, heat/pressure in mantle forces magma along cracks in earth’s crust, magma erupts at surface (volcano), layers of ash/lava heightens volcano over time

52
Q

How are shield volcanoes formed at constructive plate boundaries?

A

Plates move apart, magma rises up to plug gap (new rock), some magma may be forced along a crack/vent + erupt at surface, a submarine volcano is formed, volcano grows higher after constant eruptions

53
Q

What is a natural hazard?

A

An event over which people have no control, but threatens people’s lives/possessions,

54
Q

What are 4 methods used to monitor volcanoes?

A

Measuring earthquakes (using seismographs), tiltmeters, digital time lapse cameras, GPS

55
Q

When did the eruption of Eyjafjallajokull occur?

A

It continuously erupted from late March 2010-October 2010

56
Q

When was the ash cloud (of Eyjafjallajokull) released?

A

14th April 2010

57
Q

Where is the volcano (Eyjafjallajokull) located?

A

Southern Iceland

58
Q

What was the main local impact of the Eyjafjallajokull eruption?

A

Primary: Heavy ash fell close to volcano
Secondary: flooding due to melted glacier that was on top of volcano

59
Q

What were the local responses to the Eyjafjallajokull eruption?

A

People had to evacuate, livestock put inside, rescuers wore face masks to prevent choking on dense ash, people breached embankments to protect bridges from flood water

60
Q

What were the global impacts of the Eyjafjallajokull eruption?

A

ash cloud caused an 8 day flight ban where around 107,000 flights were cancelled, Kenya affected (20% economy from perishable goods) so over 50,000 farmers unemployed-their goods not sold

61
Q

What were the positive impacts of the Eyjafjallajokull eruption?

A

Icelandic tourist attraction and tourist centre, good crops (from nutrient rich ash), valuable materials are often found in volcanic regions

62
Q

What are signals of a volcanic eruption?

A

Swelling of the magma chamber (and base of volcano) and higher concentration of gases emitted from volcano (such as sulphur dioxide)

63
Q

What are the characteristics of a supervolcano?

A

larger scale, emit at least 1000 km3 of material (when erupting), have a large caldera

64
Q

What is a caldera?

A

a large depression

65
Q

How are calderas formed?

A

Rising magma can’t escape, crust bulges, crust cracks, gas/ash escapes, magma chamber collapses forming caldera

66
Q

Where is the Yellowstone supervolcano?

A

North America

67
Q

How would population be threatened by a Yellowstone eruption?

A

Entire N. American population would be damaged, but an ash cloud of that size could threaten world population

68
Q

How big is the magma chamber of the Yellowstone supervolcano?

A

It’s thought to be 80 km long, 40 km wide and 8 km deep

69
Q

What would be the direct impacts of a supervolcanic eruption?

A

All life up to 1000 km away destroyed by lava/falling ash/force of explosion, 1000 km3 lava, amount of ash and gas would block most of the sun’s rays

70
Q

What would be the secondary impacts of a supervolcanic eruption?

A

Harsh winter across Earth (little sun), starvation (no crops), economic collapse

71
Q

When and where was the last supervolcanic eruption?

A

Toba, Indonesia, 74,000 years ago -caused a 6 year volcanic winter

72
Q

When was the last eruption at Yellowstone?

A

640,000 years ago

73
Q

How much lava would be created by a Yellowstone eruption?

A

1000 km3 ; enough to cover the whole of North America in a layer 12.5 cm thick

GCSE Geography (6 decks)

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