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AQA Physical Geography > The restless earth > Flashcards

The restless earth Flashcards

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1
Q

What is the crust?

A

The outer layer of the earth.

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2
Q

What is the crust split into?

A

Plates of varying size and at plate margins.

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3
Q

Why are the plates at plate margins able to move?

A

Due to the slabs of crust floating on the semi-molten upper mantle.

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4
Q

What determines plate movement?

A

Convection currents within the mantle.

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5
Q

What are the two types of crust? 2

A
  • oceanic

* continental

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6
Q

What is the mantle?

A

The dense, mostly solid layer between the outer core and the crust.

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7
Q

What are the properties of the oceanic crust? 4

A
  • newer
  • denser
  • can sink
  • can be renewed and destroyed
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8
Q

What are the properties of the continental crust? 4

A
  • older
  • less dense
  • cannot sink
  • cannot be renewed or destroyed
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9
Q

What are the types of plate margin? 3

A
  • destructive
  • constructive
  • conservative
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10
Q

What occurs at a destructive plate margin?

A

The denser oceanic crust sinks under the lighter continental crust through subduction. Great pressure is exerted and the oceanic crust is destroyed as it melts to form magma.

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11
Q

What is the collision boundary?

A

If two continental plates meet each other, they collide.

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12
Q

What happens at a constructive plate margin? 4

A
  • plates pull away from each other
  • cracks and fractures form between the plates where there is no solid crust
  • magma forces its way into the cracks to the surface to form volcanoes
  • new land is formed as the plates gradually pull apart
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13
Q

What happens at a conservative plate margin? 6

A
  • plates are sliding past each other
  • moving in similar direction
  • moving at slightly different speeds/angles
  • plates tend to get stuck
  • build-up of pressure causes them to release
  • sudden release of pressure cause an earthquake
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14
Q

What are fold mountains and ocean trenches a result of?

A

Plates moving together.

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15
Q

What mountain ranges include young fold mountains? 4

A
  • Himalayas
  • the Rockies
  • the Andes
  • the Alps
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16
Q

Why are older ocean trenches less high?

A

Due to erosion.

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17
Q

What do older fold mountains include? 2

A
  • Cambrian mountains

* Cumbrian mountains

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18
Q

Where do ocean trenches form?

A

In some of the deepest parts of the ocean.

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19
Q

What are the 2 types of volcano?

A
  • composite

* shield

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20
Q

Where do composite volcanoes occur?

A

Destructive plate margins.

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21
Q

Where do shield volcanoes occur?

A

Constructive plate margins.

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22
Q

Can you describe a composite volcano? 7

A
  • crater
  • steep slopes
  • narrow base
  • eruptions infrequent
  • eruptions violent
  • secondary cones
  • layers of thick lava and ash
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23
Q

Can you describe a shield volcano? 7

A
  • low, rounded peak
  • wide base
  • gentle slopes
  • eruptions frequent
  • eruptions non-violent
  • layers of runny lava, with little ash
  • crater
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24
Q

What case study will you use for fold mountains?

A

The Andes and its people.

25
Q

What are the ways in which the Andes are used? 4

A
  • farming
  • mining
  • hydroelectric power
  • tourism
26
Q

How is farming used in the Andes? 5

A
  • grow potatoes which are main source of food
  • use of terraces
  • llamas carry materials for irrigation and buildings into inhospitable and inaccessible areas
  • llamas can carry over 25% of their body weight
  • female llamas used for meat and milk, their wool is used in clothes and rugs
27
Q

What advantages does terracing in the Andes offer? 3

A
  • retain water in an area that receives little
  • limit the downward movement of the soil
  • cash crops are produced
28
Q

How are the Andes used for mining? 5

A
  • rank in the top ten for tin, nickel, silver and gold
  • half of Peru’s exports
  • has the largest gold mine
  • Cajamarca has grown from 30,000 inhabitants to 240,000 in 2005 bringing source of jobs
  • growth led to lack of services and increased crime rate
29
Q

How are the Andes used for hydroelectric power? 4

A
  • steep slopes and narrow valleys
  • they can be more easily dammed
  • relief encourages the rapid fall of water
  • melting snow increases the supply of water
30
Q

How are the Andes used for tourism? 2

A
  • many natural attractions

* show how people settled in these inhospitable areas (Macchu Picchu)

31
Q

Where are volcanoes located?

A

Relates closely to plate margins. The area around the Pacific Ocean is prone to volcanoes.

32
Q

What caused the eruption of Nyiragongo?

A

Disturbed by the movement of plates along the East African rift valley.

33
Q

What were the primary effects of Nyiragongo volcano?

A
  • destroyed many homes
  • destroyed roads and water pipes
  • set off explosions in fuel stores
  • killed 45 people
34
Q

What were the secondary effects of Nyiragongo? 7

A
  • 0.5 million people fled to Rwanda so to escape the lava
  • no shelter, electricity or clean water as area couldn’t cope with the influx
  • diseases such as cholera were a huge risk
  • people were frightened of going back
  • looting was a problem
  • many residents returned within a week in the hope of aid
  • Oxfam were involved in the distribution of food, medicine and blankets
35
Q

What were the immediate responses to the eruption of Mt Helens? 7

A
  • mobilising helicopters for search and rescue
  • rescuing survivors was a priority
  • emergency treatment at nearby towns
  • ash clogged air-conditioning
  • ash blocked roads
  • ash was cleared within 3 days of eruption
  • Carter promised to send 2 million masks
36
Q

What are the positive impacts of the eruption of Mt Helens? 4

A
  • ash improved quality of soil by increasing its fertility
  • sterile moon has been transformed to be bursting with life
  • has become a better-known area after the eruption
  • $1.4 million spent to transform area
37
Q

What were the long-term responses to the eruption of Mt Helens? 6

A
  • buildings and bridges needed rebuilding
  • drainage in the area had to be looked at to see that flooding would not occur
  • forest began to be replanted
  • removal of fallen timber
  • roads need to be rebuilt
  • attempts to bring tourists back
38
Q

How was the eruption of Mt Helens monitored? 5

A
  • bulge that appeared on northern flank was evidence of moving magma
  • tiltmeters can identify small, subtle changes in the landscape
  • GPS use satellites to detect movement of as little as 1mm
  • change in temperature can be seen on satellite images
  • digital cameras can photograph events relatively safely
39
Q

How was the eruption of Mt Helens predicted? 7

A
  • samples were collected from the crater entrance
  • “spiders” can monitor changes
  • past frequency of eruptions
  • gap between eruptions
  • pattern of lava flows
  • ash movement
  • lahars
40
Q

What are the characteristics of a supervolcano? 3

A
  • much bigger scale than volcanoes
  • emit at least 1,000km3 of material
  • have calderas
41
Q

What are the likely effects of a supervolcano eruption? 8

A
  • destroy 10,000km3 of land
  • kill 87,000 people
  • 15cm of ash would cover buildings with 1,000km
  • 1 in 3 people affected would die
  • ash would affect transport, electricity, water and farming
  • lahars are a probability
  • global climates would change
  • crops would fail
42
Q

How do earthquakes occur at destructive plate margins?

A

Pressure resulting from the sinking of the subducting plate and its subsequent melting can trigger strong earthquakes as this pressure is periodically released.

43
Q

How do earthquakes occur at constructive plate margins?

A

Tend to be less severe. The friction and pressure caused by the plates moving apart.

44
Q

How do earthquakes occur at conservative plate margins?

A

Great strength. Where the plates slide past each other, they tend to stick. This causes stress and pressure to build. The release of pressure occurs in a sudden, quick release and the result is an earthquake.

45
Q

What is an earthquake’s focus?

A

The place where the earthquakes begin, deep within the earth’s crust.

46
Q

What is the epicentre of an earthquake?

A

The point at the earth’s surface directly above the focus.

47
Q

What are an earthquake’s shock waves?

A

Seismic waves generated by an earthquake that pass through the earth’s crust.

48
Q

What caused the Kobe earthquake?

A

Philippines Plate shifted uneasily beneath the Eurasian Plate along the Nojima fault line that runs beneath Kobe.

49
Q

What were the primary effects of the Kobe earthquake? 5

A
  • 5000 died
  • 300,000 made homeless
  • 102,000 buildings destroyed
  • worst affected area was the centre
  • estimated cost for rebuilding £100billion
50
Q

What were the secondary effects of Kobe? 4

A
  • emergency aid for the city needed to use damaged roads
  • raised motorways collapsed during the shaking
  • many small roads were closed by fallen debris from buildings, cracks or bumps
  • 300 fires took 2 days to put out
51
Q

What were the immediate responses? 3

A
  • clean, fresh water supply was in short supply until April
  • many people had to sleep in cars or tents in cold winter conditions
  • government was criticised for being slow to rescue people
52
Q

What were the long-term responses? 5

A
  • water, electricity, gas and telephone services were fully working by July 1995
  • railways were back in service by August 1995
  • 80% of the port was working a year after
  • by January 1999, 134,000 housing units had been constructed
  • new laws were passed to make buildings and transport structures even more earthquake proof
53
Q

What caused the Haiti earthquake?

A

Caribbean Plate south of the fault line was sliding east and the smaller Gonvave Plate north of the fault was sliding west.

54
Q

What were the immediate impacts of the Haiti earthquake? 8

A
  • 316,000 people died
  • 1 million people made homeless
  • Port Au Prince crumbled to dust
  • 3 million people affected
  • 250,000 residences damaged
  • 30,000 commercial buildings damaged
  • rubble blocked roads and rail links
  • roads were littered with cracks
55
Q

What were the short term responses to Haiti earthquake? 4

A
  • many countries responded to appeals for aid, pledging funds and dispatching rescue and medical teams
  • communication systems had been damaged which slowed rescue and aid efforts
  • there was much confusion over who was in charge, air traffic congestion complicated early relief work
  • supplies, medical care and sanitation were priorities
56
Q

What were the long term responses? 5

A
  • EU gave $330 million and the World Bank waived the countries debt repayments for 5 years
  • 98% of rubble remained un cleared 6 months later
  • $1.1 billion had been collected for Haiti for relief efforts
  • 1 million people remained displaced a year later
  • Dominican Republic offered support and accepted some refugees
57
Q

What caused the Indian Ocean tsunami?

A

Info-Australian Plate subducting beneath the Eurasian Plate.

58
Q

What were the effects of the Indian Ocean tsunami? 7

A
  • 220,000 people died
  • 650,000 seriously injured
  • 2 million made homeless
  • public buildings were wiped out
  • pictures were posted in the hope that loved one had survived
  • identification of the dead on such a scale was an issue
  • 1,500 settlements were believed to have been wiped out completely in Banda Aceh
59
Q

What were the responses to the Indian Ocean tsunami? 8

A
  • rescue services were swamped
  • injured people were untreated for days
  • bodies littered the streets
  • fresh water, water purification tablets, food, sheeting and tents all poured in as aid
  • UK government promised £75 million
  • £372 million had been donated by the British public
  • £128 million had been sent out by DEC
  • plans to spend £190 million building 20,000 homes for 100,000 homeless people

AQA Physical Geography (3 decks)

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