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Edexcel A-Level Geography > 1.1 Tectonic processes and hazards > Flashcards

1.1 Tectonic processes and hazards Flashcards

1
Q

Types of natural hazard (2)

A
  • hydro-meteorological (caused by climatic
    processes)
  • geophysical (caused by land processes)
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2
Q

Define intra-plate earthquakes

A
  • Earthquakes near the middle of plates
  • plates have pre-existing weaknesses which become reactivated, forming seismic waves.
  • e.g. an intraplate earthquake may occur if solid crust, which has weakened over time, cracks under pressure.
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3
Q

Define inter-plate earthquakes

A
  • an earthquake that occurs at the boundary between two tectonic plates
  • usually at conservative, collision, or destructive boundaries
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4
Q

What is a volcanic hotspot?

A
  • hotspots are situated amongst the centre of plates
  • a localised area of the lithosphere which has an unusually high temperature due to the upwelling of hot molten material from the core
  • At hotspots, magma rises as plume
  • e.g. Hawaii
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5
Q

Define the OFZ (Oceanic Fracture Zone)

A

a belt of activity through the oceans and along the mid-ocean ridges through Africa, the Red Sea, the Dead Sea

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6
Q

Define the CFZ (Continental Fracture Zone)

A

a belt of activity along the mountain ranges from Spain through the Alps to the Middle East and to the Himalayas.

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7
Q

Describe tectonic trends since 1960 (4)

A

▪ total number of recorded hazards has increased
▪ number of fatalities has decreased - some spikes during mega disasters.
▪ population growth means total number of people being affected by tectonic hazards is increasing
▪ economic costs increased significantly - due to development as infrastructure in more developed countries costs more to repair, and increasing number of insurance policies

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8
Q

Why is reporting disaster impacts difficult? (4)

A

▪ Depends on whether you look at the direct deaths or indirect deaths due to secondary impacts
▪ Location: rural and isolated areas are hard to reach and so hard to collect data from them. Similarly, data may be difficult to collect in areas with very high population densities.
▪ Different methods may be used by different organisations so as a result different sources may quote different figures
▪ The number of deaths quoted by a government could be subject to bias

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9
Q

4 layers of the Earth’s structure

A
  • crust (lithosphere)
  • mantle (asthenosphere)
  • outer core
  • inner core
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10
Q

Describe the crust (3)

A
  • uppermost, thinnest, least dense, and lightest layer
  • Oceanic crust is only 7km thick
  • continental crust can be up to 70km thick.
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11
Q

Describe the mantle (4)

A
  • Largely composed of silicate rocks, rich in iron and magnesium
  • semi-molten
  • temperature gradient (towards the core) generates convection currents, which causes to the circulation of the mantle and may contribute to the lithosphere’s plate tectonic movement.
  • from 700km to 2890km below the surface
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12
Q

Describe the outer core (2)

A
  • Dense, semi-molten rocks containing iron and nickel alloys.
  • 2890km to 5150km below the Earth’s surface.
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13
Q

Describe the inner core (3)

A
  • Similar composition to the outer core.
  • over 5150km below the Earth’s surface
  • solid due to the extreme pressures it experiences
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14
Q

Why does the inner core experience such high temperatures? (2)

A

○ primordial heat left over from the earth’s formation
○ radiogenic heat produced from radioactive decay

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15
Q

Describe convection currrents

A
  • hot magma rises because it becomes less dense with heat
  • magma cools at the top as it is further away from the heat source
  • it then becomes more dense and sinks back down
  • cooler magma is reheated and begins to rise again
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16
Q

Describe a destructive plate boundary between a continental and oceanic plate (7)

A

● Denser oceanic plate subducts below the continental.
● leaves a deep ocean trench.
● oceanic crust melts as it subducts
● extra magma created causes pressure to build up.
● Pressurised magma forces through weak areas in the continental plate
● composite volcanoes erupt through the continental plate
● Fold mountains occur when sediment is pushed upwards during subduction.

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17
Q

Describe a destructive plate boundary between 2 oceanic plates (3)

A

● Heavier plate subducts leaving an ocean trench and fold mountains
● Built up pressure causes underwater volcanoes bursting through oceanic plate.
● Lava cools and creates new land called island arcs.

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18
Q

Describe a collision plate boundary (5)

A

● 2 continental plates
● Both plates are not as dense as oceanic so lots of pressure builds.
● there is no subduction of continental crust.
● Pile up of continental crust on top of lithosphere due to pressure between plates.
● Fold mountains formed from piles of continental crust.

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19
Q

Describe a constructive plate boundary between 2 oceanic plates (3)

A

● Magma rises in between the gap left by the two plates separating, forming new land when it cools.
● Less explosive underwater volcanoes formed as magma rises.
● New land forming on the ocean floor by lava filling the gaps is known as sea floor spreading (as the floor spreads and gets wider).

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20
Q

Describe a constructive plate boundary between continental plates (4)

A

● Any land in the middle of the separation is forced apart, causing a rift valley.
● Volcanoes form where the magma rises.
● Eventually the gap will most likely fill with water and separate completely from the main island.
● The lifted areas of rocks are known as horsts whereas the valley itself is known as a graben.

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21
Q

Describe a conservative plate boundary (5)

A
  • Between any crust, the parallel plates move in different directions or at different speeds.
  • No plates are destroyed so no landforms are created
  • When these plates move, a lot of pressure is built up.
  • On oceanic crust, this movement can displace a lot of water.
  • On continental crust, fault lines can occur where the ground is cracked by the movement.
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22
Q

Describe paleomagnetism and how it provides evidence of seafloor spreading

A
  • As new rock is formed and cools the magnetic grains within the rock align with the magnetic poles
  • Our poles switch periodically. Each time these switch the new rocks being formed at plate boundaries align in the opposite direction to the older rock.
  • On the ocean floor either side of constructive plate boundaries, Geologists observed that there are symmetrical bands of rock with alternating bands of magnetic polarity.
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23
Q

What are different mechanisms causing plate movements? (3)

A
  • slab-pull
  • ridge-push
  • convection currents
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24
Q

Describe ridge-push

A
  • The slope created when plates move apart has gravity acting upon it as it is at a higher elevation.
  • Gravity pushes the plates further away, widening the gap
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25
Q

Describe slab-pull

A
  • When a plate subducts, the plate sinking into the mantle pulls the rest of the plate (slab) with it, causing further subduction
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26
Q

How has tectonic theory changed?

A
  • tectonic movement isn’t fully understood.
  • Previously, convection currents were thought to be the primary cause of plate movement.
  • However, researchers now believe that Slab Pull is the primary mechanism for plate movement
  • convection currents seem too weak to move massively dense plates.
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27
Q

What causes an earthquake?

A
  • Plates do not perfectly fit into each other so plates can become stuck due to the friction
  • the convection currents in the asthenosphere continue to push, which builds the pressure
  • the plates eventually give way.
  • All of this pressure is released in a sudden movement, causing a jolting motion in the plates.
  • This is responsible for seismic movement spreading throughout the ground in the form of seismic waves
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28
Q

Define the focus (or hypocentre) of an earthquake

A
  • the point underground where the earthquake originates from
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29
Q

Define the epicentre of an earthquake

A
  • the area above ground that is directly above the focus
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30
Q

Name the 4 types of seismic waves

A
  • primary
  • secondary
  • love
  • rayleigh
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31
Q

Describe primary waves (P-Waves)

A
  • Travels through solids
  • Compressional
  • Vibrates in the direction of travel
  • Travels at 4-8 km/s
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32
Q

Describe secondary waves (S-waves)

A
  • Vibrate at right angles to direction of travel
  • Travels only through solid rocks
  • Travels at 2.5 - 4 km/hr
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33
Q

Describe love waves

A
  • Near to ground surface
  • Rolling motion producing vertical ground movement
  • Travels at 2-6 km/hr
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34
Q

Describe Rayleigh waves

A
  • Vertical and horizontal displacement
  • Travels at 1-5 km/hr
  • Compressional
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35
Q

Which types of wave are most destructive?

A
  • Secondary and Love waves are the most destructive as they have large amplitudes. - Due to their different speeds, these different waves will hit a location at different times.
  • The aftershocks that survivors feel are these different types of waves arriving after each other.
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36
Q

What affects the intensity of a seismic wave?

A
  • Intensity will decrease further from the epicentre, as waves lose energy as they travel.
  • this does not mean that impacts felt or damage caused will always decrease further from the epicentre as other factors affect a location’s vulnerability
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37
Q

Factors affecting an area’s vulnerability to earthquakes (5)

A
  • geology
  • geographical location (whether the earthquake occurs near the sea or intraplate)
  • education of locals,
  • durability of buildings
  • mitigation
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38
Q

Name 3 secondary impacts of earthquakes

A
  • soil liquefaction
  • landslides
  • tnusamis
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39
Q

Describe liquefaction

A

● Affects poorly compacted sand and silt.
● Water moisture within the soil separates from the soil particles and rises to the surface.
● This can cause the soil to behave like a liquid, which can cause building subsidence or landslides.

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40
Q

Describe landslides caused by earthquakes

A

● The shaking caused by the earthquake can weaken or damage cliff faces, hills and snow material.
● Unconsolidated material or loose rocks can collapse.
● Landslides can travel several miles and accumulate material on the way.
● Risk varies with topography rainfall, soil and land use.

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41
Q

Describe tsunamis

A

● When an oceanic crust is jolted during an earthquake, all of the water above this plate is displaced
● This water is then pulled back down due to gravity. The energy is transferred into the water and travels through it like a wave.
● The water travels fast but with a low amplitude
● As it gets closer to the coast there is friction between the sea bed and the waves.
● This causes the waves to slow down and gain height

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42
Q

Where do tsunamis usually occur?

A
  • Tsunamis are generated generally in subduction zones at convergent plate margins.
  • Most tsunamis are found along the Pacific ring of fire
  • hence the most vulnerable countries are often located in Asia or Oceania
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43
Q

Physical factors affecting tsunami impacts (5)

A
  • geographical location
  • Duration of the event
  • Wave amplitude and distance travelled
  • Gradient of the continental shelf
  • The shape of the land - bays will funnel and concentrate tsunami waves.
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44
Q

Human factors affecting tsunami impacts (4)

A

● Population density of area hit, if the population is higher than more people are likely to be affected
● Coastal defences (e.g. Tsunami walls)
● Warning & Evacuation Systems
● Level of economic and human development

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45
Q

Describe strato (composite) volcanoes

A
  • steep-sided cones formed from layers of ash and acidic lava flows.
  • lava is viscous so it cannot travel far down the slope of the volcano before it cools.
  • usually found at destructive plate margins.
  • Most composite volcanoes contain complex internal networks of lava flows which contain intrusive (below ground) igneous features
  • e.g. Mount Fuji, Mount St Helens
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46
Q

Describe the eruption of a composite volcano

A
  • The eruptions from these volcanoes may be a pyroclastic flow rather than a flow of lava.
  • When composite volcanoes erupt they are explosive and pose a threat to nearby life and property.
  • Eruptions are explosive due to the thick, highly viscous lava that is produced by composite cone volcanoes.
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47
Q

What is a caldera?

A
  • A caldera is a volcanic crater
  • They form when an explosive eruption destroys the cone and the magma chamber below is emptied.
  • Without magma providing support below a caldera is formed when the sides of the volcano collapse.
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48
Q

Describe a shield volcano

A
  • Shield volcanoes are low with gently sloping sides and are formed from layers of lava.
  • Eruptions are typically non-explosive. Shield volcanoes produce fast flowing basic (fluid) lava that can flow for many miles.
  • Eruptions tend to be frequent but relatively gentle.
  • Although these eruptions destroy property, death or injury to humans rarely occurs.
  • Shield volcanoes are usually found at constructive boundaries and sometimes at volcanic hotspots.
  • e.g. Mount Kilauea and Maunaloa on Hawaii.
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49
Q

Define strombolian eruption

A
  • The effects are impressive but not particularly dangerous.
  • They eject short bursts of lava 15 to 90 meters in the air.
  • The lava has a fairly high viscosity, so gas pressure builds up before the material can be ejected from the volcano.
  • Lava flows from Strombolian eruptions are not common though they do produce small amounts of ash.
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50
Q

Define vulcanian eruptions

A
  • Vulcanian eruptions involve violent gas explosions that blow out sticky plugs of lava.
  • These fragments build up cones of ash and pumice.
  • Lava is very viscous and solidifies rapidly.
  • The eruption usually clears a blocked vent and releases a significant amount of ash.
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51
Q

Define Vesuvian eruptions

A
  • vesuvian eruptions involve very large blasts of gas that force large ash clouds into the sky.
  • They are more violent than Vulcanian eruptions.
  • Ash falls on the surrounding area and lava flows can also happen.
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52
Q

Define Plinian eruptions

A
  • most explosive and violent of volcanic eruptions.
  • They produce huge plumes of ash and gas that typically takes the shape of a huge mushroom cloud.
  • They are highly explosive and the AD79 eruption that buried Pompeii was one of these.
  • started by highly viscous magma that has high gas content.
  • As the magma emerges it depressurizes and this allows the gas to expand, propelling pyroclastic material as high as 45 km in the air
  • These eruptions can last for days and create a sustained and tall eruption plume, which drops a huge amount of tephra, fallen volcanic material, on surrounding areas.
  • Additionally, a Plinian eruption can produce extremely fast-moving lava flows that destroy everything in their path.
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53
Q

Primary hazards caused by volcanic eruptions (4)

A
  • lava flows
  • pyroclastic flows
  • tephra and ash flows
  • volcanic gases
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54
Q

Describe lava flows

A

– Streams of lava that have erupted onto the Earth’s surface

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55
Q

Factors affecting magma types (3)

A
  • silica content
  • viscosity
  • gas content
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56
Q

How does magma’s silica content, viscosity, and gas content affect an eruption’s explosivity?

A
  • As viscosity, silica content, and gas content increase, explosivity increases
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57
Q

Describe pyroclastic flows

A
  • a mixture of hot dense rock, lava, ash and gases which move very quickly along the surface of the Earth.
  • Due to their high speeds, they are extremely dangerous and can cause asphyxiation for anyone caught by the flow.
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58
Q

Describe tephra and ash flows

A
  • When pieces of volcanic rock and ash are blasted into the air.
  • This can cause serious damage to buildings, which can collapse under the weight of ash or tephra
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59
Q

Describe volcanic gases

A
  • Gases like sulphur dioxide and carbon monoxide are released into the atmosphere.
  • Due to their potency, volcanic gases can travel long distances.
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60
Q

Secondary hazards caused by volcanic eruptions (3)

A
  • lahars
  • jokulhaup
  • acid rain
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61
Q

describe lahars

A
  • Combination of rock, mud and water which travel quickly down the sides of volcanoes.
  • These can occur when the heat of the eruption causes snow and ice to melt or alternatively when an eruption coincides with heavy rainfall.
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62
Q

Describe a jokulhaup

A

– Snow and ice in glaciers melt after an eruption which causes sudden floods that are very dangerous

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63
Q

Describe acid rain

A
  • caused when gases such as sulfur dioxide are released into the atmosphere by an eruption and dissolve in rain
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64
Q

Define multiple-hazard zone

A
  • Multiple hazard zones are places where two or more natural hazards occur, and in some cases interact to produce complex disasters.
  • Examples are California, Indonesia and Japan.
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65
Q

Features of multiple-hazard zones (4)

A
  • tectonically active and so earthquakes (and often eruptions) are common
  • geologically young with unstable mountain zones prone to landslides
  • often on major storm tracks either in the mid-latitudes or on tropical cyclone tracks
  • suffer from global climate perturbations such as ENSO
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66
Q

Define disaster

A

A serious disruption of the functioning of a community or society involving human, material, economic and environmental losses which exceeds the ability of the affected community or society to cope using its own resources

67
Q

What is the Risk equation?

A

Risk (R) = (Hazard (H) x Vulnerability (V))/ capacity to cope (C)

68
Q

When might a place be high risk?

A
  • Their capacity to cope is low.
  • They are quite vulnerable.
  • The hazard is large/ high intensity.
69
Q

What is the difference between a hazard and a disaster?

A
  • A disaster will only occur when a vulnerable population (one that will be significantly disrupted and damaged) is exposed to a hazard
  • Different organisations will define a hazard and disaster differently, based on their interests and what they believe is most important
70
Q

What does the Park Model show?

A
  • The Park Model is a graphical representation of human responses to hazards.
  • The model shows the steps carried out in the recovery after a hazard, giving a rough indication of time frame.
  • The steepness of the curve shows how quickly an area deteriorates and recovers.
  • The depth of the curve shows the scale of the disaster
71
Q

4 stages of the Park model

A
  • pre-disaster
  • relief
  • rehabilitation
  • reconstruction
72
Q

Describe the relief stage of the Park model

A
  • hours-days after event
    ● Immediate local response - medical aid, search and rescue
    ● Immediate appeal for foreign aid - the beginnings of global response
73
Q

Describe the rehabilitation stage of the Park model

A
  • days-weeks after event
    ● Services begin to be restored
    ● Temporary shelters and hospitals set up
    ● Food and water distributed
    ● Coordinated foreign aid - peacekeeping forces etc.
74
Q

Describe the reconstruction stage of the Park model

A
  • weeks-years after the event
    ● Restoring the area to the same or better quality of life
    ● Area back to normal - ecosystem restored, crops regrown
    ● Infrastructure rebuilt
    ● Mitigation efforts for future events
75
Q

How can the Park model be used?

A
  • The model works as a control line to compare hazards.
  • An extremely catastrophic hazard would have a steeper curve than the average and would have a slower recovery time than the average
76
Q

What is the Pressure and Release Model used for?

A
  • used to analyse factors which cause a population to be vulnerable to a hazard
  • On one side of the model we have the natural hazard itself, and on the other side different factors and processes which increase a population’s vulnerability to the hazard.
  • This vulnerability is often rooted in social processes
77
Q

What are the three factors affecting vulnerability under the PAR?

A
  • root causes are often caused by economic, demographic and/or political processes, often affecting large populations or entire countries.
  • Dynamic pressures are local economic or political factors, that can affect a community or organisation
  • unsafe conditions are the physical conditions that affect an individual
78
Q

Types of root causes

A

Limited access to:
- power
- structures
- resources
Ideologies:
- political systems
- economic systems

79
Q

Types of dynamic pressures

A

Lack of
- training
- local investment
- press freedom
Macro-forces:
- rapid population change
- rapid urbanisation
- deforestation

80
Q

Types of unsafe conditions

A
  • physical
  • environment
  • local economy
  • social relations
  • public actions
81
Q

Define physical vulnerability

A

Individuals live in a hazard-prone area, with little protection naturally or through mitigation.

82
Q

Define economic vulnerability

A

People risk losing their employment, wealth or assets during a hazard. MEDCs tend to be more economically vulnerable than LEDCs

83
Q

Define social vulnerability

A

Communities are unable to support their disadvantaged or most vulnerable, leaving them at risk to hazards

84
Q

Define knowledge vulnerability

A
  • Individuals lack training or warning to know the risks of a hazard or how to safely evacuate.
  • Alternatively, religion and beliefs may limit their understanding of hazards; hazards are an act of God, so individuals don’t mitigate or evacuate (known as fatalist belief)
85
Q

Define environmental vulnerability

A

A community’s risk to a hazard is increased due to high population density in the area

86
Q

Examples of root causes (3)

A
  • Weak Governance
  • Mismanagement by Industry, NGOs or IGOs
  • High reliance on products easily affected by hazards (local agriculture near to the hazard, imports by air during a volcanic eruption)
87
Q

Examples of dynamic pressures

A
  • lack of training/knowledge in locals.
  • rapid urbanisation
  • poor communication between government and locals
  • natural environment degraded (mangroves removed, rivers & channels filled with debris)
  • lack of basic services (health, education, police)
88
Q

Examples of unsafe living conditions

A
  • lack of infrastructure (clean water, sewage removal, electricity)
  • dangerous location of settlements (close to nuclear stations or the natural hazard itself)
  • no warning system for locals
  • disease and fire can easily spread between households
89
Q

What does a tectonic hazard profile do?

A
  • A hazard profile compares the physical characteristics which all hazards share.
  • Hazard Profiles can help decision makers when deciding where to allocate the most human and financial resources
90
Q

What characteristics are included in a Hazard Profile? (7)

A
  • magnitude
  • speed of onset
  • areal extent
  • duration
  • frequency
  • spatial predictability
91
Q

How effective are hazard models?

A
  • Hazard models are useful, but the unpredictability of hazards makes the models less effective at accurately representing human responses to hazards
92
Q

Describe the Volcanic Explosivity Index (VEI)

A

● Measures the relative explosiveness of a volcanic eruption.
● Based on the height of ejected material and duration of eruption.
● Scale goes from 0-8 and is logarithmic (increase of 1 on the scale indicated a 10 times more powerful eruption).

93
Q

Describe the Modified Mercalli Scale

A

● Measures the destructiveness of an earthquake.
● It is a relative scale as people would feel different amounts of shaking in different places.
● It subjective as based on if people wake up, if furniture moves, how much damaged structures receive.
● The scale varies from I to XII
I = Generally not felt by detected on seismographs
XII = Nearly total destruction
● It doesn’t consider economic, social and environmental impacts.

94
Q

Describe the Moment Magnitude Scale

A

● Measures the amount of energy released in earthquake.
● Scale has no upper limit (highest recorded was 9.5)
● It’s a simple measure, so environmental or social impacts must be inferred.

95
Q

Describe the Richter Scale

A

● Measures the amplitude of the waves produces during an earthquake
● Most widely used scale, as it’s absolute
● Must infer social or environmental impacts, which can be misleading. The highest Richter scale earthquake readings won’t necessarily be the worst disasters.
● Like the VEI its scale is logarithmic.

96
Q

What are the 4 components of the response and risk management to volcanic hazards plan?

A
  • prevention
  • preparedness
  • mitigation
  • adaptation
97
Q

Describe prevention of volcanic hazards

A
  • volcanic eruptions cannot be prevented
  • only the risk to people can be prevented by not allowing people near volcanic hazards (e.g. preventing buildings around volcanoes)
98
Q

Describe preparedness to volcanic hazards

A
  • monitoring increases the notice of volcanic eruptions, meaning warning can be given out
  • education on volcanoes in areas of risk so people know what to do
99
Q

Describe mitigation against volcanic hazards

A
  • direct intervention to the volcano (e.g. concrete blocks to steer lava away from areas at risk)
  • strengthening buildings that are at risk of mudflows or ash pileup
  • evacuation and exclusion zones
  • mitigation effects on health by having emergency aid and rescue
100
Q

Describe adaptation to volcanic hazards

A
  • moving away from area at risk
  • capitalise on opportunities, such as encouraging tourism
  • change profession so it is less likely to be affected by volcanic hazards
101
Q

What is the hazard management cycle?

A

The Hazard Management Cycle outlines the stages of responding to events , showing how the same stages take place after every hazard.

102
Q

What are the four stages of the hazard management cycle?

A
  • preparedness
  • response
  • recovery
  • mitigation
103
Q

Define preparedness

A

Being ready for an event to occur (public awareness, education, training)

104
Q

examples of preparedness

A
  • Developing preparation plans
  • Developing warning systems
  • Stockpiling medicines, food, water etc.
  • Education, training, drill
105
Q

Define response

A

Immediate action taken after event, the main aims would be to rescue people and reduce economic losses

106
Q

Examples of responses

A
  • Search and rescue efforts
  • Evacuating people
  • Restoring vital infrastructure like water and electricity
  • Restoring vital services like law enforcement and health care
107
Q

Define recovery

A

Long-term responses (restoring services, reconstruction)

108
Q

Define recovery

A

Long-term responses (restoring services, reconstruction)

109
Q

Define mitigation

A

Identifies the characteristics of the potential hazard and what can be done reduce their impact on people

110
Q

Examples of mitigation

A
  • Land use zoning
  • Building codes and regulation
  • Protective defences (tsunami wall)
111
Q

How can the risk of an earthquake be predicted?

A
  • not possible for us to predict accurately when a earthquake will happen
  • risk of an earthquake can be forecast based on a statistical likelihood
  • Forecasts can be based on data and evidence gathered through global seismic monitoring networks and from historical records
112
Q

How are volcanoes predicted?

A

● Small earthquakes - called tremors
● Changes to the top surface of the volcano as it swells when magma builds up
● Changes to the tilt as the slope angle changes when magma builds up

113
Q

Examples of short-term aid

A
  • Providing aid, food, water, shelter
  • Providing financial assistance so people can rebuild their livelihoods
114
Q

Examples of long-term aid

A
  • Rebuilding homes
  • Building and repairing infrastructure
  • Reopening schools and businesses
115
Q

Name the three different approaches to managing hazards

A
  • Modify the Event
  • Modify the Vulnerability
  • Modify the Loss.
116
Q

How can events be modified on a micro scale?

A

Strengthening individual buildings and structures

117
Q

How can events be modified on a macro scale?

A

→ Large scale support and protective measures designed to protect whole communities

118
Q

Modifying the event - earthquakes

A
  • Mainly micro approach
  • Emphasis put into public buildings like hospitals, police stations and other vital infrastructure
  • Schools and factories strengthened to help shelter people
  • Some improvements to private houses
119
Q

Modifying the event - tsunamis

A
  • Tsunami walls which work for a given amplitude and threshold of wave
  • Replanting coasts with mangroves and coastal forestry which dissipates energy from waves
120
Q

Modifying the event - volcanoes

A
  • Diverting flows of lava
  • Reinforce house roofs to withstand large deposits of ash
121
Q

Examples of modifying the event (4)

A
  • land use zoning
  • resistant buildings
  • tsunami defences
  • lava diversion
122
Q

Describe land use zoning

A

Preventing building on low lying areas and areas of high risk

123
Q

Advantages of land use zoning

A
  • low cost
  • reduces vulnerability
124
Q

Disadvantages of land use zoning

A
  • Stops economic development on some high value land
  • Strict enforcement required
125
Q

Define resistant buildings

A

Buildings with deep foundations, sloped roofs so that ash doesn’t build and create pressure

126
Q

Advantages of resistant buildings

A
  • Can help prevent collapsing
  • Protects people and property
127
Q

Disadvantages of resistant buildings

A
  • High cost for larger buildings
  • Low income families cannot afford this
128
Q

Describe tsunami defence

A

Sea walls which stop waves travelling inland

129
Q

Advantages of tsunami defences

A
  • Reduces damage
  • Provides security
130
Q

Disadvantages of tsunami defences

A
  • Very high cost
  • Doesn’t look nice
  • Can be overtopped
131
Q

Describe lava diversion

A

Barriers and water cooling to divert and slow down lava flow

132
Q

advantages of lava diversion

A
  • Diverts lava away
  • Low cost
133
Q

Disadvantages of lava diversion

A

Only works for low VEI lava

134
Q

Examples of modifying the vulnerability (3)

A
  • hi tech scientific monitoring
  • community preparedness and education
  • adaptation
135
Q

advantages of Hi Tech Scientific Monitoring

A
  • Predicting eruption is possible in some cases
  • Warning and evacuation can help save lives
136
Q

Disadvantages of hi tech scientific monitoring

A
  • Costly, in LDCs, volcanoes aren’t usually monitored
  • Doesn’t prevent property damage
137
Q

Advantages of community preparedness and education

A
  • Low cost and often implemented by NGOs
  • can save lives through small actions
138
Q

Disadvantages of community preparedness and education

A
  • Doesn’t prevent property damage
  • Harder to implement in isolated rural areas
139
Q

Advantages of adaptation

A
  • Helps save lives and property
140
Q

Disadvantages of adaptation

A
  • High population densities prevent it
  • Disrupts people’s traditional home and traditions
141
Q

Modifying the loss examples (3)

A
  • short term aid
  • long term aid
  • insurance
142
Q

Advantages of short term aid

A
  • Can help reduce death toll by saving lived and keeping people alive until long term aid is provided
143
Q

Disadvantages of short term aid

A
  • High costs and technical difficulties in isolated areas
  • Emergency services are limited and are poorly equipped in LDC
144
Q

Advantages of long term aid

A
  • Reconstruction can help improve resilience through
    land use planning and better construction methods
145
Q

Disadvantages of long term aid

A
  • Very high costs
  • Needs are quickly forgotten by the media shortly are the disaster
146
Q

Advantages of insurance

A
  • Allows people to recover economically for paying reconstruction
147
Q

Disadvantages of insurance

A
  • Doesn’t help save lives
  • Not many in LDCs have insurance
148
Q

Describe the role of communities in modifying losses

A

In remote and isolated areas, it may take a long time for aid to come and people may begin local recovery operations, communities may clear debris from roads and set up temporary shelters.

149
Q

Describe the roles of NGOs and TNCs in modifying losses

A
  • NGOs play a very important role from providing funds, coordination rescue efforts and helping to develop reconstruction plans.
  • Occasionally, TNCs and NGOs may cooperate; Charity buckets or events may be organised by businesses to improve NGOs ability to help.
150
Q

Why might less developed countries be more vulnerable to hazards?

A
  • Governments of developing countries may not prioritise investing money in hazard mitigation as they tend to focus their resources on development and economic growth.
  • This lack of investment in hazard management often means that less developed countries and
    their populations are more vulnerable to hazards.
151
Q

Human factors contributing to a population’s vulnerability (4)

A
  • unstable political governance and/or corruption
  • population density
  • geographical isolation and accessibility
  • level of urbanisation
152
Q

How might unstable political governance and/or corruption increase vulnerability?

A

a lack of political cohesion can impact on how prepared a country is for a hazard and can also negatively impact response and recovery efforts after the event.

153
Q

How might population density increase vulnerability?

A

the higher the population density the more people affected by a hazard.

154
Q

How might geographical isolation and accessibility increase vulnerability?

A

remote, rural areas often have poor transport links which can negatively effect rescue efforts.

155
Q

How might levels of urbanisation increase vulnerability?

A

urban areas tend to be worse affected by hazards due to two factors:
- urban areas are densely populated
- they have larger amounts of infrastructure meaning there is more economic damage.

156
Q

Factors caused by governance that increase vulnerability (4)

A
  • meeting basic needs
  • planning
  • preparedness
  • corruption
157
Q

Describe how meeting basic needs affects vulnerability

A

When food supply, water supply and health needs are met, the population is generally less vulnerable to secondary hazards such as diseases.

158
Q

Describe how land-use planning affects vulnerability

A

Land-use planning can reduce risk by preventing people living in areas of high risk. Secondary hazards may be made worse by deforestation

159
Q

Describe how preparedness affects vulnerability

A

Education and community preparation programmes raise awareness and teach people how to prepare, evacuate and act when a disaster strikes.

160
Q

Describe how corruption affects vulnerability

A
  • If government politicians accept bribes and do unethical things, then vulnerability would increase as money may not be invested in crucial areas like emergency services.
161
Q

What are the characteristics of tectonic mega-disasters?

A

▪ Large scale disaster affecting a large spatial areas or large population.
▪ They pose problems in effective management to minimise the impacts.
▪ The scale of the impact may require international support and aid.
▪ Mega Disasters are low probability (rare).

162
Q

Global impact of mega-disasters

A
  • The globalisation of production and supply chains has allowed international businesses to reduce the costs and become more efficient.
  • However, mega-disasters significantly damage globalised businesses
  • e.g. Tohoku 2011, Eyjafjallajokull 2010
163
Q

Benioff zone

A

A region of the subducting plate, most affected by pressure and friction, where most destructive margin earthquakes originate.

Edexcel A-Level Geography (16 decks)

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