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✅👁️Y1 Geography Physical > Paper 1 - Section A - Tectonic Processes and Hazards > Flashcards

Paper 1 - Section A - Tectonic Processes and Hazards Flashcards

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1
Q

Define a hazard

A

A potential threat to human life and property

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2
Q

Define a disaster

A

An event which has effected people or civilisation in any way

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3
Q

Where are tectonic hazards distributed around the world? (Think plate boundary types etc) — and consider anomalies!!

A

Earthquakes:

  • predominantly convergent plate boundaries
  • intraplate tectonics: central plate activities which occurs due to weaknesses in the crust

Volcanoes:

  • predominantly around convergent plate boundaries
  • hotspots: in the centre of plates where hot molten material breaks its way through weakened crust
  • pacific ring of fire
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4
Q

What are the names of the 7 major plates?

A
  1. African plate
  2. Antarctic plate
  3. Eurasian plate
  4. Pacific plate
  5. Indo-Australian plate
  6. North American plate
  7. South American plate
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5
Q

What are the names of the 7 minor plates?

A
  1. Arabian plate
  2. Caribbean plate
  3. Cocos plate
  4. Nazca plate
  5. Juan de Fuca plate
  6. Philippine sea plate
  7. Scotia plate
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6
Q

List the changes in the trends of tectonic activity since the 1960s in terms of frequency of events, number of fatalities / costs etc

A
  • total number of recorded hazards has increased
  • number of fatalities has decreased
  • total number of people being affected by the hazards has increased due to population growth
  • economic costs associated with hazards has increased
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7
Q

What makes reporting disaster impacts difficult?

A
  • depends on whether direct or indirect deaths are recorded
  • location: rural / isolated areas hard to get data from
  • different methods / sources document different statistics
  • number of deaths stated by governments subject to bias
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8
Q

Starting from the innermost section, name the 4 sections within the earths structure

A
  1. Inner core:
  • Over 5000km below earths surface
  • solid due to high pressure
  1. Outer core:
  • over 2900km below earths surface
  • dense semi molten rock
  1. Mantle (asthenosphere):
  • over 700km below earths surface
  • semi molten
  • convection currents due to temperature gradient
  1. Crust (lithosphere):
  • thinnest, lightest, uppermost layer of earth
  • oceanic crust: 7km thick
  • continental crust: 70km thick
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9
Q

Describe the landforms a convergent plate margin creates

A

Continental + continental:
- fold mountains
- earthquakes

Continental + oceanic

  • fold mountains
  • earthquakes
  • volcanoes

Oceanic + oceanic:

  • ocean trenches
  • island arcs
  • earthquakes
  • volcanoes
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10
Q

Describe the landforms a divergent plate margin creates

A

Continental + Continental:

  • rift valleys
  • volcanoes

Oceanic + oceanic

  • ocean ridges
  • volcanoes
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11
Q

Describe the landforms a conservative plate margin creates

A
  • earthquakes
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12
Q

Define Benioff zone

A

A seismically active underground area with a subduction zone

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13
Q

Describe the process of mantle plumes occurring i.e Hawaii island arc

A
  1. Hot magma rises through weak parts of the oceanic lithosphere (melts it) which forms new volcanic island
  2. As tectonic plate moves over stationary hotspot / plume, volcano shifts along
    which forms a new volcanic island
  3. A chain of volcanic islands are created (island arcs)

The further down the chain, the more old / extinct / eroded they become

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14
Q

Describe the 5 stages of mantle convection

A
  1. The core heats up the magma within mantle
  2. Hot mantle becomes less dense — RISES
  3. As it travels further from the heat source, it cools — becomes LESS DENSE
  4. It then begins to sink
  5. The cycle repeats!

(Takes place within the asthenosphere)

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15
Q

Define paleomagnetism

A

Study of past changes in earths magnetic field

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16
Q

Describe the process of paleomagnetism I.e mid Atlantic ridge

A

Every 400,000 years or so, the earths magnetic fields change direction (poles swap)

Scientists discovered same pattern of magnetic direction on either side of the ridge (can only happen if new rock got formed at the same time on both sides)

(Sea floor progressively ages, the further it is from the ridge)

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17
Q

Describe the process of sea floor spreading, and what landforms can it create?

A

Occurs at mid ocean ridges, where new oceanic crust is formed through volcanic activity
Which then gradually moves away from the ridge

Hot magma gets forced through asthenosphere before hardening; forming new ocean crust

OCCURS AT DIVERGENT PLATE BOUNDARIES

(Plates pushed apart by hot magma, forming new oceanic crust: mid ocean ridges, underwater mountain ranges)

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18
Q

Describe the process of subduction

A

This is when one plate sinks beneath another at a convergent boundary

As oceanic + oceanic or continental + oceanic plates move towards each other, one slides underneath and meets at a subduction zone

(Despite seafloor spreading the earth isn’t expanding, as new crust is being formed in a location it’s being destroyed in another)

(Zone where lithosphere is recycled back into the mantle at the surface, the subduction zone coincides with the bottom of the trenches)

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19
Q

Describe the process of slab pull

A

Pulling forces exerted by cold, dense oceanic plate plunges them into the mantle due to their density and weight
(Aka subduction)

Newly formed oceanic lithosphere at mid ocean ridges are less dense than the asthenosphere (becomes denser as it ages) — sinks into mantle at subduction zones, pulling lithosphere slabs apart (divergent boundaries)

The descending plate which is pulled into the asthenosphere melts

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20
Q

At what plate margins does mantle convection occur?

A
  • divergent
  • convergent
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21
Q

At what plate margins does paleomagnetism occur?

A
  • divergent
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22
Q

At what plate margins does sea floor spreading occur?

A
  • divergent
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23
Q

At what plate margins does subduction occur?

A
  • convergent
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24
Q

At what plate margins does slab pull occur?

A
  • divergent
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25
Q

What are the 3 types of earthquake waves?

A
  1. Primary waves
  2. Secondary waves
  3. Love waves
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26
Q

Which 2 earthquake waves are known as body waves and which is known as a surface wave?

A

Body waves: (travel through earths body)

  • primary 8km/s; travels through solids, compressional, vibrates in direction of travel
  • secondary 4km/s; travels only through solid rocks, vibrates at right angles to direction of travel, large amplitude

Surface wave: (travel through earths surface)

  • love: higher amplitude / most destructive; near to ground surface, rolling motion movement, large amplitude
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27
Q

What are the differences between the two types of crust?

A

Oceanic: high density — 3.0mg/m^3, mainly basalt, thin, new

Continental: low density — 2.6mg/mg^3, mainly granite, thick, old

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28
Q

Define hypocentre

A

Point within the earth where an earthquake rupture starts

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29
Q

Define epicentre

A

Point on the earths surface directly above the hypocentre

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30
Q

Secondary hazards: what is the process of soil liquefaction?

A

It affects poorly compacted sand and silt

  1. Moisture in the ground separates from the soil particles and rises to the surface making it waterlogged (due to the large tremors)
  2. Shaking destabilises the soil by increasing the space between the grains
  3. This can cause the soil to behave like a liquid and loses its strength, which can cause building subsidence or landslides
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31
Q

Secondary hazards: how do landslides occur?

A
  1. Earthquake tremors can weaken / damage cliff faces, hills and snow material
  2. In consolidated material or loose rocks can collapse
  3. Landslides can travel several miles and accumulate sediment along tour way

Risk varies with topography, rainfall, soil and land use

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32
Q

What are the 5 stages to a tsunami?

A
  1. Earthquake causes fault or plate boundary to jolt at the seabed, causing a column of water to vertically displace
  2. Gravity pulls this water back down, transferring the energy through the water in the form of a wave
  3. The water travels outwardly at a fast pace yet a low amplitude (height)
  4. As this water approaches the coast, the seabeds get shallower creating friction between the bed and the waves
  5. This causes the water to slow down and gain height, creating a wall of water that can reach 100ft
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33
Q

Which type of zones are tsunamis typically created?

A

Subduction zones (convergent plate margins)

I.e pacific ring of fire

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34
Q

Define a wave train

A

A succession of similar tsunami waves at equal intervals

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35
Q

What varies the impact of a tsunami?

A
  • population density
  • coastal defences
  • duration of the event
  • wave amplitude and distance travelled
  • warning / evacuation systems
  • level of economic development
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36
Q

Name 4 primary hazards as a result of a volcano

A
  1. Lava flows
  2. Pyroclastic flows
  3. Tephra and ash flows
  4. Volcanic gases
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37
Q

What are lava flows?

A

Streams of lava which have erupted onto the earths surface — fast flowing lava can be dangerous (depends on viscosity)

Explosiveness and viscosity depends on it’s silicon content

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38
Q

What are pyroclastic flows?

A

Mixture of hot rock, lava, ash and gases which move very rapidly along the earths surface — extremely dangerous

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39
Q

What is tephra / ash flows, and it’s impact on surrounding buildings?

A

When pieces of volcanic rock and ash are blasted into the air — can seriously damage buildings which collapse under their weight

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40
Q

What are volcanic gases?

A

Sulphur dioxide and carbon monoxide get released into the atmosphere — can travel long distances due to their potency

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41
Q

Name 3 secondary hazards as a result of a volcano

A
  1. Lahars
  2. Jokulhlaups
  3. Acid rain
42
Q

What are lahars / how do they occur

A

A combination of rock, mud and water which quickly travel down the sides of volcanoes
Can occur due to meltwater from volcano heat or when an eruption coincides with heavy rainfall

43
Q

What are jokulhlaups?

A

Snow and ice glacier meltwater after an eruption which causes sudden flooding

44
Q

What is acid rain?

A

When sulphur dioxide gets released into the atmosphere and mixes with the moisture in the air

45
Q

What is the hazard risk equation?

A

Risk = hazard x vulnerability
——————————
Capacity to cope

46
Q

What factors make a place at high risk?

A
  • if their capacity to cope is low
  • they are quite vulnerable
  • the hazard is large / high intensity
47
Q

What is isostatic readjustment / post-glacial adjustment?

A

Where ice masses / glaciers caused the land mass to sink

The weight of the ice compresses the land

When this ice melts the crust can rise

48
Q

Name the 2 types of volcanic eruptions

A
  1. effusive
  2. explosive
49
Q

Describe what an effusive volcanic eruption is like

A
  • Where lava steadily flows out of a volcano onto the ground
  • dissolved gases escape easily
  • sloping shield volcanoes I.e Hawaii
50
Q

Describe what an explosive volcanic eruption is like

A
  • occurs when cooler, more viscous magma reaches the surface
  • dissolved gases cannot escape easily
    — causes pressure to build
  • gas explosions; rock bombs
51
Q

What are the two shapes of a volcano?

A
  1. composite volcano i.e Mt Fuji
  2. shield volcano I.e eyjafjallajokull
52
Q

Why do people live in hazardous volcano zones?

A
  • fertile soils
  • minerals
  • tourism
  • family ties
  • cheaper living
53
Q

Define a submarine earthquake

A

Convergent plate boundary which displaces the water column above (causes tsunamis)

54
Q

What is a locked fault?

A

Fault which cannot ‘slip’ because the frictional resistance on the fault is greater than the sheer stress along the fault

55
Q

Who came up with the theory of continental drift?

A

Alfred Wegener

56
Q

Continental crust properties:

                      Continental

Age

Colour
+ example

Thickness

Density

A

Continental

Age. >1500 mil years old

Colour light I.e granite
+ example

Thickness 35-40 km on average

Density light: 2.6 mg/m^3

57
Q

Oceanic crust properties:

                      Oceanic

Age

Colour
+ example

Thickness

Density

A

Oceanic

Age >200 mil years

Colour Dark I.e basalt
+ example

Thickness 6-10km on average

Density Heavy: 3.0 mg/m^3

58
Q

What is a harmonic tremor and what are they typically followed by?

A

Continuous rhythmic earthquakes which can be detected by seismographs

  • often precede volcanic eruptions
  • underground movement of magma
  • long duration
59
Q

How did wegener prove his theory, and what discovery in 1948 concluded that the plates were being driven apart

A
  • geological and fossil evidence which connects broken up continents

Rocks of similar age and type found in Africa and South America

1948 mid Atlantic ridge was discovered — suggested processes were driving the plates apart

60
Q

Composite volcano properties:

                      Composite

Temp

Margin

Silica

Gas

Lava viscosity

A

Composite volcano properties:

                      Composite

Temp Cooler: 600-800°

Margin Convergent

Silica High: 70%

Gas High: 4-6%

Lava viscosity Thick

61
Q

Shield volcano properties:

                      Shield

Temp

Margin

Silica

Gas

Lava viscosity

A

Shield volcano properties:

                      Shield

Temp Hotter: 1000-1200°

Margin Divergent

Silica High: 70%

Gas Low: 0.5-2%

Lava viscosity Runny

62
Q

What are the 3 types of lava?

A
  1. Andesitic lava
  2. Basaltic lava
  3. Rhyolitic lava
63
Q

Define magnitude

A

Measures amount of energy released at the epicentre

64
Q

What are the 2 types of magma, and some of their proprieties?

A
  1. Basic magma
    - rich in iron, aluminium
    - low silica content
    - low viscosity
  2. Acid magma
    - rich in silica
    - relatively low temp
    - high viscosity
65
Q

What is the MMS (moment magnitude scale) and what does it record?

A

It measures large earthquakes

Records:
- size of seismic wave
- resistance of affected rocks
- amount of slippage

66
Q

What is the Mercalli scale and what does it record? Is it reliable?

A

It measures large earthquakes

Records:
- intensity of earthquakes
- based on opinion; subjective; unreliable
- uses amount of damage as an indicator of earthquakes intensity

  • it doesn’t consider economic, environmental and social impacts
67
Q

What does the VEI (volcanic explosivity index) record?

A

Records:
- measures relative explosiveness of a volcanic eruption
- based on height of ejected material and duration of eruption
- scale goes from 0-8 and is logarithmic

68
Q

What does the Richter scale record?

A

amplitude of waves produced during and earthquake
- most widely used scale
- logarithmic scale
- must infer social or environmental impact which can be misleading

69
Q

What does the PAR (pressure and release model) measure?

A

It’s used to analyse factors which causes a population to be vulnerable to a hazard

It considers the hazard itself and along with the factors that determine the populations vulnerability

  • complex
70
Q

What factors increase the resilience of a community?

A
  • positive attitude of people
  • pre-planning
  • good communications
  • wealth of nation
  • emergency procedures
  • foreign debt repayments
  • medical supplies available
71
Q

What factors decrease the resilience of a community?

A
  • low doctor patient ratio
  • lack of skills
  • unequal trade agreements
  • rapid population growth
  • environmental degradation
  • large scale rural to urban migration
72
Q

What characteristics are on a hazard profile? (Conducted after hazard occurs)

A
  1. frequency of hazard
  2. Magnitude — how extensive it could affect
  3. Duration — how long it lasts
  4. Speed of onset
  5. Fatalities
  6. Economic loss
  7. Spatial predictability — where would be affected
73
Q

What are hazard profiles used for?

A

Help with decision making when deciding where to allocate most human and financial resources

74
Q

What human and physical factors affect the severity of hazards on populations?

A

Human:
- wealth
- access to education
- housing
- healthcare
- income opportunities

Physical:
- accessibility
- urbanisation
- population density

75
Q

How does governance / investment influence the scale of a disaster?

A
  • corruption
  • building codes and regulations
  • preparedness plans
  • infrastructure
  • emergency services
  • communication systems
  • public education and practised hazard response
76
Q

What are the issues with using hazard profiles?

A
  • degree of reliability in comparing different events
  • easy to compare hazards of same type however difficult to compare across hazards as they have different impacts
  • difficult to gather data from remote areas
77
Q

What is a mega disaster?

A

A high magnitude, high impact, infrequent disaster that affects several countries directly or indirectly

78
Q

Define a multiple hazard zone

A

A place where multiple hazards occur

79
Q

Describe the pattern of multiple hazard zones around the world

A

They are predominantly in Asia (including japan, the Philippines, Taiwan, Indonesia) along with Central America (Guatemala, Costa Rica)

80
Q

How can scientists predict when earthquakes happen?

A

Currently it isn’t possible to predict

Earthquake risk can be forecasted bashed on statistical likelihood

81
Q

What role do scientists play in prediction and forecasting?

A

The encourage and enforce stricter building regulations by the government

82
Q

How is hazard risk reduced?

A
  • disaster preparedness
  • adaption to climate change
  • development
  • disaster recovery
  • disaster response
  • disaster mitigation
83
Q

What is the hazard management cycle?

A

A process in which governments and other organisations work together to protect people from the natural hazards that threaten their communities

AIM: REDUCE LOSS OF LIFE AND PROPERTY

84
Q

What are the stages within the hazard management cycle?

A

Before the hazard event;

  Preparation

HAZARD EVENT;

  Response

After hazard event;

  Recovery

  Mitigation
85
Q

What are they key players within the hazard management cycle?

A
  • governments
  • international organisations
  • businesses
  • community groups
86
Q

How can tsunamis, earthquakes and volcanoes be prepared for?

A

Tsunamis:

  • infrastructure I.e seawalls
  • tsunami warning systems i.e DART

earthquakes:

  • monitor seismic activity
  • hazard profiles
  • land-use zoning

Volcanoes:

  • hazard maps
  • monitor temperatures
  • visual signs I.e ice melting, cone changing shape
  • lava flows diversions
87
Q

Define mitigation

A

Ways to prepare in advance in the event of a hazard

88
Q

Define adaption

A

Strategies designed to reduce the impacts of hazard events i.e education, community preparedness

89
Q

What are some mitigation strategies

A
  • houses on wheels
  • mounds / channels
  • diversion of lava flows
  • land-use zoning
90
Q

What is the parks model?

A

A graphical representation of human responses to hazards to hazards. It shows out the steps of recovery after a hazard giving a rough indication of timeframe

Steepness of curve:

Shows how quickly an area deteriorates and recovers

Depth of curve:

Shows scale of disaster

91
Q

What are the 3 stages to the parks model? (3 R’s)

A

Stage one — relief
Hours to days

Stage two — rehabilitation
Days to weeks

Stage three — reconstruction
Weeks to years

92
Q

Name some examples of short term aid

A
  • providing aid, water, food, shelter
  • providing financial assistance so people can rebuild their livelihoods
93
Q

Name some examples of long term aid

A
  • rebuilding homes
  • building and repairing infrastructure
  • reopening schools and businesses
94
Q

What is the role of insurers during disasters?

A

Insurance coverage can help communities recover from disaster

In many countries few people have insurance as more pressing economic needs take priority
— they are more vulnerable + less resistant

I.e New Zealand had insurance and was rebuilt in 2 years (2011 Christchurch) whereas Haiti 2010 didnt

95
Q

What is the role of NGO’s and TNC’s during disasters?

A

They provide funds, coordinate rescue efforts and help develop reconstruction plans

Charity events may be hosted to raise money

96
Q

What inequalities may affect a communities resilience to a hazard?

A
  • asset inequality
  • political inequality
  • social status inequality
  • entitlement inequality
97
Q

What are aseismic buildings?

A

Buildings designed to withstand or minimise destruction during an earthquake

98
Q

What is continental drift?

A

The movement of tectonic plates, due to varying weights of crust. It was originally thought that convection currents caused the movement of the plates, but now slab pull is thought of as the primary driving force

99
Q

What is Degg’s model?

A

A model that shows that a hazard becomes a disaster if it affects a vulnerable population

100
Q

What is a love wave?

A

A surface earthquake wave with horizontal displacement

101
Q

What are primary waves?

A

An earthquake wave causing compressions within the body of rock

102
Q

What are secondary waves?

A

An earthquake wave causing vertical displacement within the body of rock

✅👁️Y1 Geography Physical (2 decks)

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