1
Q
What’s a hazard?
A
- A hazard is a potential threat to human life and property caused by an event
- Anthropogenic causes or natural causes
- An event only becomes a hazard when it becomes a threat to people
- Hazards shouldn’t be confused with natural disasters – a disaster will only occur when a vulnerable population is exposed to a hazard
2
Q
What are the three types of geographical hazard?
A
- Geophysical
- Atmospheric
- Hydrological
- Hazards can be classed as a mixture of these geographical processes e.g. a tropical storm could be classed as a hydrological-atmospheric hazard
3
Q
What’s a geophysical hazard?
A
– caused by land processes, mainly tectonic plates e.g. volcanic eruptions
4
Q
What’s an atmospheric hazard?
A
– Caused by atmospheric processes and the conditions created because of these, such as weather systems e.g. wildfires
5
Q
What’s a hydrological hazard?
A
– Caused by water bodies and movement e.g. floods
6
Q
What’s hazard perception?
A
- People have different views of how dangerous hazards are, and what risks they pose, depending on economic and cultural lifestyle factors
7
Q
Hazard perception - wealth
A
– Wealthier people may perceive a hazard to be less of a risk as they’re less vulnerable (e.g. they have the ability to evacuate with transport access and can build stronger houses)
- However, they may also view the risk as greater as there’s more risk of property damage and financial loss
8
Q
Hazard perception - experience
A
- Someone who has experienced more hazards may be more likely to understand their full effects, and may have an optimistic and unrealistic outlook
9
Q
Hazard perception - education
A
– Someone who’s more educated on hazards may understand their full effects
10
Q
Hazard perception - religious beliefs
A
- Some may view hazards as God’s creation, and part of the natural cycle of life, something positive
- However, those who believe strongly in environmental conservation may perceive hazards to be a huge risk to the environment
11
Q
Hazard perception - mobility
A
- Those who have limited access to escape hazards may perceive them to be greater threats than they are
12
Q
What are human responses to hazards?
A
- Hazards can be responded to in an active or passive way
- Active responses to hazards are strategies used to contribute to a lower hazard risk
13
Q
Human responses to hazards - Fatalism
A
– The view that hazards are uncontrollable natural events, and any losses should be accepted, as nothing can be done to present them
– This is passive
14
Q
Human responses to hazards - prediction
A
– The use of scientific research and past events in order to predict when a hazard will take place, so that warnings can be delivered and the impacts can be reduced
- In some cases, hazards can be prevented when predicted early enough
15
Q
Human responses to hazards - adaptation
A
– Attempting to live with hazards by adjusting lifestyle choices, so that vulnerability to the hazard is lessened
16
Q
Human responses to hazards - mitigation
A
– Strategies carried out to reduce the severity of a hazard
17
Q
Human responses to hazards - management
A
– Co-ordinated strategies to reduce a hazard’s effects – this includes prediction, adaptation, and mitigation
18
Q
Human responses to hazards - risk sharing
A
– A form of community preparedness, where the community shares the risk posed by a natural hazard, and invests collectively to mitigate the impacts of future hazards
19
Q
What’s an example of risk sharing?
A
- New Zealand is an example of where risk sharing has been successful
- As a multi-hazard environment, New Zealand is under threat from earthquakes, tsunamis, volcanoes, and weather-related hazards
- The costs of these hazards are huge; the Canterbury Earthquake (2010) alone costed the country 20% of its national GDP
- There are now attempts to share the risk through insurance investment, so strategies can be put in place before the disasters rather than investing more in a clean up
20
Q
Aspects of hazards and how they affect human response - incidence
A
– The frequency of a hazard – how often a hazard occurs, not affected by the strength
- Low incidence hazards may be harder to predict, and there tends to be less management strategies put in place, meaning the hazard could be more catastrophic
- Low incidence hazards are usually more intense than high incidence hazards, e.g. there are only 36 recorded earthquakes since 1500 that were a magnitude of 8.5 or higher, but millions of earthquakes that are too weak to be recorded are thought to happen every year
21
Q
Aspects of hazards and how they affect human response - distribution
A
– Where hazards occur geographically
- Areas of high distribution are likely to have a lot of management strategies, and those living there will be adapted to the hazardous landscape
22
Q
Aspects of hazards and how they affect human response - intensity
A
– The power of a hazard – how strong it is and how damaging the effects are
23
Q
Aspects of hazards and how they affect human response - magnitude
A
– The size/scale of the hazard – this is usually how a hazard’s intensity is measured
- High magnitude, high intensity hazards will have worse effects, meaning they require more management e.g. more mitigation strategies
- Magnitude and intensity aren’t interchangeable terms – the magnitude is usually definable and can be a number, and this doesn’t change. Intensity, however, is the effects on the person, and can change depending on distance from the hazard, or the management strategies used
24
Q
Aspects of hazards and how they affect human response - level of development
A
– Economic development will impact how well an area can respond to a hazard – a hazard of the same magnitude may have different effects in two different places, due to contrasting levels of development
- The effects of a hazard are likely to be much more catastrophic in a less economically developed area
- However, there are many HICs that aren’t as prepared as they should be – this is especially true in multi-hazardous environments where resources are spread over a variety of hazards
25
What's an example of how level of development affects human response?
- In Canada, where the number of wildfires has been increasing (as a result of climate change), less money and resources have been available for earthquake and tsunami preparation - even detailed evacuation routes and tsunami sirens aren’t available on popular tourist beaches, such as Vancouver Island
- SMS systems are available to act as a warning system, however many people switch their phones off at night, reducing the effectiveness
26
What's the park model?
- A graphical representation of human responses to hazards, showing the steps carried out in recovery after a hazard with a rough indication of the 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 (the lower the curve, the lower the quality of life)
- The model also works as a control line to compare hazards – an extremely catastrophic hazard would have a slower recovery time than the average hazard
27
What's stage 1 of the park model?
- Relief (hours - days)
- Immediate local response – medical aid, search and rescue
- Immediate appeal for foreign aid – the beginning of global response
28
What's stage 2 of the park model?
- Rehabilitation (days - weeks)
- Services begin to be restored
- Temporary shelters and hospitals are set up
- Food and water are distributed
- Coordinated foreign aid – peacekeeping forces, etc.
29
What's stage 3 of the park model?
- Reconstruction (weeks - years)
- 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
30
What's the hazard management cycle?
- Outlines the stages of responding to events, showing how the same stages take place after every hazard
- Preparedness, response, recovery, mitigation
31
What's preparedness?
- Being ready for an event to occur (public awareness, education, training)
32
What's response?
- Immediate action taken after an event (evacuation, medical assistance, rescue)
33
What's recovery?
- Long-term responses (restoring services, reconstruction)
34
What's mitigation?
- Strategies to reduce the effects of another hazard (barriers, warning signals, observatories)
35
Evaluation of the effectiveness of models
- Hazard models are useful, but the unpredictable nature of hazards makes the models less effective at accurately representing human responses to hazards
1. Can they be applied to every hazard?
2. Do more complicated hazards require a more complex model?
3. Does the model take every aspect of the hazard into account e.g. level of development?
4. Do the models accurately lay out the time taken for a full response, and how this can change due to aspects such as intensity?
5. Could the model be less vague/include more steps that can be applied to all hazards?
6. Does the model represent hazards currently e.g. are there any alterations that could be made to account for hazards affected by climate change?
36
What's the structure of the earth?
- Inner core
- Outer core
- Mantle
- Asthenosphere
- Lithosphere
- Crust
37
What's the inner core?
- Solid ball of iron/nickel
- Very hot due to pressure and radioactive decay – contains elements such as uranium which give off heat when they decompose
- This heat is responsible for the earth’s internal energy, and it spreads throughout
38
What's the outer core?
- Semi-molten
- Iron/nickel
39
What's the mantle?
- Mainly solid rock, and the rocks are high in silicon
- However, the very top layer of the mantle is semi-molten magma, which is known as the asthenosphere. The lithosphere rests on top
40
What's the asthenosphere?
- Semi-molten layer constantly moves due to flows of heat called convection currents
- Movement is powered by heat from the core
- The lithosphere is above
41
What's the lithosphere?
- Broken up into plates
- The majority of the lithosphere is within the mantle
- The top of the lithosphere is the crust, which is the land and sea we live on
42
What's the crust?
- The thin top layer of the lithosphere
- The oceanic crust is dense, and is destroyed by plate movement
- The continental crust is less dense, and isn’t destroyed
43
What's plate tectonic theory?
- The lithosphere is broken up into large slabs of rock called tectonic plates
- These plates move due to convection currents in the asthenosphere, which push and pull the plates in different directions
- Convection currents are caused when the less dense magma rises, cools, and then sinks
- The edges where plates meet are called plate boundaries/plate margins
44
What's the process of convection currents?
1. Heat from the inner core convects through the mantle into the asthenosphere
2. Hot magma rises as it becomes less dense with heat, as particles spread out
3. The magma is cooler at the top as it’s further away from the heat source – it becomes denser and sinks back down to the bottom
4. Cooler magma is reheated and begins to rise again, creating a loop called a convection current
45
What are the three types of plate boundary?
- Destructive - plates move apart
- Constructive - plates move towards each other
- Conservative - plates slide past each other
46
Destructive plate boundary - continental & oceanic
- The denser oceanic plate subducts below the less dense continental plate
- The plate subducting leaves a deep ocean trench
- Fold mountains occur when sediment is pushed upwards during subduction
- The oceanic crust is melted as it subducts into the asthenosphere
- The extra magma created causes pressure to build up
- Pressurised magma forces through weak areas in the continental plate
- Explosive, high-pressure volcanoes erupt through the continental plate – these are known as composite volcanoes
47
Destructive plate boundary - oceanic & oceanic
- The heavier plate subducts, leaving an ocean trench and fold mountains
- Built up pressure causes underwater volcanoes to burst through the oceanic plate
- Lava cools and creates new land called island arcs
48
Destructive plate boundary - continental & continental
- Both plates aren’t as dense as the oceanic plate, so lots of pressure builds
- Ancient oceanic crust is subducted slightly, but there’s no subduction of continental crust
- Continental crust piles up on top of the lithosphere due to the pressure between the plates
- Fold mountains formed from piles of continental crust
49
Constructive plate boundary - oceanic & oceanic
- Magma rises in between the gap left by the two plates separating, forming new land when it cools
- Less explosive underwater volcanoes are formed as magma rises
- New land forming on the ocean floor by lava filling the gaps is known as sea floor spreading
- Paleomagnetism
50
What's paleomagnetism?
- The study of rocks that show the magnetic fields of the earth
- As new rock is formed and cools, the magnetic grains within the rock align with the magnetic poles
- Our poles switch periodically – each time they 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 – this is evidence of sea floor spreading
51
Constructive Plate Boundary - Continental & Continental
- 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 rock are known as horsts, whereas the valley itself is known as a graben
- Ridge push and slab pull
52
What's ridge push?
- The slope created when plates move apart has gravity acting upon it, as it’s at a higher elevation
- Gravity pushes the plates further away, widening the gap (known as gravitational sliding)
53
What's slab pull?
- When a plate subducts, the plate sinking into the mantle pulls the rest of the plate with it, causing further subduction
54
What occurs at conservative plate boundaries?
- 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 builds 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
55
What are hotspots?
- Areas of volcanic activity that aren’t related to plate boundaries
- Hot magma plumes from the mantle rise and burn through weaker parts of the crust – this can create volcanoes and islands
- The plume stays in the same place, but the plates continue to move, which sometimes causes a chain of islands e.g. Hawaii
56
Hazards associated with volcanic eruptions - lava flows
- Lava can flow quickly or slowly, depending on its viscosity
- Silica makes lava viscous and slow, which is common in explosive eruptions
57
Hazards associated with volcanic eruptions - lahars (mudflows)
- Caused by a number of reasons, usually by melting ice at high latitudes
58
Hazards associated with volcanic eruptions - glacial floods (jokulhlaups)
- When temperatures are high from magma, glaciers or ice sheets at high temperatures quickly melt, and a large amount of water is discharged
59
Hazards associated with volcanic eruptions - tephra
- Any type of rock that’s ejected by a volcano
60
Hazards associated with volcanic eruptions - toxic gases
- Released during some eruptions
- Even CO2 can be toxic, since it’s heavier than oxygen and can therefore replaces it
61
Hazards associated with volcanic eruptions - acid rain
- Caused when gases such as sulphur dioxide are released into the atmosphere
62
Hazards associated with volcanic eruptions - nuees ardentes/pyroclastic flows
- Clouds of burning hot ash and gas that collapse down a volcano at high speeds
- Average speeds of around 60mph, but can reach 430mph
63
What's the spatial distribution of volcanoes?
- Located along constructive or destructive plate boundaries, or on hotspots
- The Ring of Fire is an area of high volcanic and earthquake activity located in the Pacific, and the majority of large volcanoes occur within this 25,000-mile belt
64
How is the magnitude of volcanic eruptions measured?
- Vulcanicity is measured using the Volcanic Explosivity Index (VEI)
- The more powerful, the more explosive
- The scale is logarithmic from VEI 2 and onwards
- Multiple features are considered when calculating the VEI – these include how much tephra is erupted, how long it lasts, and how high the tephra is ejected, etc.
- Intense, high magnitude eruptions are explosive, whereas calmer, low magnitude eruptions are effusive
65
What's the frequency of volcanic eruptions?
- Frequency of eruptions varies depending on the volcano
- Volcanoes are classed as either active, dormant, or extinct
- An estimated 50-60 volcanoes erupt each month, meaning volcanic eruptions are always frequent, and some volcanoes erupt constantly
- Usually, a higher frequency eruption means that the eruptions are effusive, whereas low frequency means the eruptions are explosive
66
What's the regularity of volcanic eruptions?
- Volcanic eruptions are regular in the way that the eruptions on each type of boundary are similar (e.g. eruptions on destructive boundaries will regularly be explosive)
- Sometimes, eruptions are irregular and don’t fit patterns
67
What's the predictability of volcanic eruptions?
- Regularity of eruptions can help with estimating when eruptions will take place (e.g. every 10 years)
- Seismic activity, gases released, elevation, etc. can all indicate an imminent eruption, but there’s no definite predictions for volcanic eruptions
68
What are the primary impacts of volcanic hazards?
- Environmental - ecosystems damaged, reduced biodiversity
- Economic - businesses and industries destroyed or disrupted
- Social - people killed, displacement, homes destroyed from lava/pyroclastic flows
- Political - government buildings destroyed or disrupted
69
What are the secondary impacts of volcanic hazards?
- Environmental - water acidified by acid rain, volcanic gases contribute to the greenhouse effect
- Economic - jobs lost, profit from tourism - Social - fires can start, mudflows or floods, trauma, homelessness
- Political - conflicts concerning government response, food shortages, insurance
70
What does prevention of volcanic hazards involve?
- Volcanic eruptions can’t be prevented – only the risk to people can be somewhat prevented, by not allowing people to be near volcanic hazards
71
What does preparation for volcanic hazards involve?
- Monitoring increases the notice of volcanic eruptions, meaning that warnings can be distributed
- Education in areas of risk ensures that people know what to do if an eruption takes place
- Evacuation procedures are planned
- Training response teams
72
What does mitigation of volcanic hazards involve?
- Direct intervention e.g. concrete blocks to steer lava away from areas at risk
- Strengthening buildings that are at risk from mudflows or ash pileup
- Evacuation and exclusion zones
- Mitigating effects on health by having emergency aid and rescue
73
What does adaptation for volcanic hazards involve?
- Moving away from areas at risk
- Capitalise on opportunities, such as encouraging tourism
- Change profession so it’s less likely to be affected by volcanic hazards
74
Why do seismic hazards occur?
- Plates don’t perfectly fit into each other, meaning they don’t move in fluid motions – at all boundaries, plates can become stuck, due to friction
- When the plates are stuck, the convection currents in the asthenosphere continue to push, which causes pressure to build up – it builds up so much that it can’t be sustained, and the plates eventually give way
- All of this pressure is released in a sudden movement, causing a jolting motion
- This jolt is responsible for seismic movement spreading throughout the ground, in the form of seismic waves/shock waves
- The focus in the point underground where the earthquake originates from
- The epicentre is the area above ground, directly above the focus
75
What's the spatial distribution of seismic hazards?
- They take place along all boundaries
- The Ring of Fire accounts for 90% of the world’s earthquakes
- The Alpine-Himalayan belt accounts for 5-6% of the world’s earthquakes
76
How is the magnitude of seismic hazards measured?
- Seismicity is measured using the logarithmic Richter Scale (0-10), which is a measure of the strength of seismic waves
- The Modified Mercalli Intensity Scale is also used – this is a rating of the destruction caused
- Unlike the Richter Scale, the Mercalli Scale has a definite end at 12 (XII)
- The Mercalli Scale is subjective, meaning it’s sometimes disputed as it’s dependent on human development being present, rather than the strength of the seismic waves
- The magnitude of the earthquake is also dependent on the depth of focus
- Conservative boundaries are the shallowest, meaning they’re closer to the epicentre, and the seismic waves are stronger
- Destructive boundaries usually have deeper focuses, meaning the seismic waves are spread over a larger area before they reach the epicentre – this is dependent on the earthquake
77
What's the frequency of seismic hazards?
- Earthquakes are frequent around the world, and occur every day at boundaries
- Hundreds of smaller magnitude earthquakes that can’t be felt by humans occur every day, whereas larger earthquakes are more frequent
78
What's the regularity of seismic hazards?
- Earthquakes follow no pattern and are random, so there’s irregularity between events
79
What's the predictability of seismic hazards like?
- Earthquakes are almost possible to predict
- Microquakes may give some indication, but the magnitude can’t be predicted
80
Hazards caused by seismic events - shockwaves/seismic waves
- When two plates move side by side, friction builds up and pressure increases
- This pressure is stored as potential energy – it can’t move so it just builds up
- When the pressure becomes too much, the plates eventually move
- All of the energy that has built up must go somewhere, so it’s transferred into kinetic energy, which is released and vibrates throughout the ground
- The further away from the focus, the weaker the shockwaves, as the energy is transferred into the surroundings
81
Hazards caused by seismic events - tsunamis
- When an oceanic crust is jolted during an earthquake, all of the water above the plate is displaced
- The water travels fast, but with a low amplitude (height)
- As it gets closer to the coast, the sea level decreases, so there’s friction between the seabed and the waves
- This causes the waves to slow down and gain height, creating a wall of water, that’s, on average, 10 feet high, but can reach 100 feet
82
Hazards caused by seismic events - liquefaction
- When soil is saturated, the vibrations of an earthquake cause it to act like a liquid
- Soil becomes weaker, and more likely to subside when it has a large weight on it
83
Hazards caused by seismic events - landslides
- Movement in soil or snow will cause it to become unstable
84
What are the primary impacts of seismic hazards?
- Environmental - earthquakes can cause fault lines which destroy the environment - Economic - businesses destroyed
- Social - buildings collapse, deaths, injuries, entrapment
- Political - government buildings destroyed
85
What are the secondary impact of seismic hazards?
- Environmental - radioactive materials and substances can leak from power plants, saltwater from tsunamis can flood freshwater ecosystems, leading to soil salinisation
- Economic - economic decline as businesses are destroyed (tax breaks, etc.), high rebuilding cost, insurance payout, sources of income lost
- Social - gas pipes rupture and start fires, water supplies are contaminated as pipes burst, diseases spread, flooding from tsunamis
- Political - political unrest from food and water shortages, borrowing money for international aid, initial chaos and ‘lawlessness’ e.g. looting
86
What does prevention of seismic hazards involve?
- The majority of seismic hazards can’t be prevented – earthquakes and tsunamic will occur regardless
- Liquefaction of soils can be prevented through soil stabilisation – gravel columns can be put in the ground
- Avalanches can be prevented through controlled explosions
87
What does preparation for seismic hazards involve?
- Earthquake prone areas (e.g. Japan) have extensive awareness strategies and education in place e.g. drop, cover, hold on
- Earthquake warning systems and tsunami warning systems after an earthquake
- Evacuation plans and training
88
What does mitigation of seismic hazards involve?
- Search and rescue, immediate emergency aid, evacuation (short term)
- Demolishing older, unsafe buildings
- Tsunami wave breaks and sea walls
89
What does adaptation for seismic hazards involve?
- Move away from areas at risk
- Capitalise on opportunities e.g. encouraging tourism
- Insurance if living in areas at risk
- Changing lifestyle choices e.g. moving valuable items so they can’t fall
- Building specially designed, ‘earthquake proof’ buildings
90
What's a tropical storm?
- A tropical storm is a low pressure, spinning storm with high winds and torrential rain
91
Conditions required for tropical storms to develop - temperature
- Ocean temperatures must be around 26-27 degrees, and at least 50 metres deep
- Warm water provides energy for the storm
92
Conditions required for tropical storms to develop - air pressure
- Must be in areas of unstable air pressure – usually where areas of high pressure and low pressure meet (convergence zones)
- This is so warm air rises more readily, and clouds can form – the air must also be humid for cloud formation
- Warm air rises because it’s less dense than cold air
93
Conditions required for tropical storms to develop - wind shear
- Winds must be present for the swirling motion to form, but not too strong or the storm system will be ripped apart in the early stages
94
Conditions required for tropical storms to develop - rotation
- Tropical storms only form around the equator, but no less than 5o on either side
- The Coriolis Effect is the effect of the earth’s rotation on weather events - the storm spins because the Earth in spinning
- However, there’s no Coriolis Effect at the equator, hence why these storms will only form a certain distance away from it
95
Conditions required for tropical storms to develop - a trigger
- A pre-existing thunderstorm, a spot of very high sea surface temperature, an area of low pressure, and many other factors can act as triggers for a storm to develop, which will only further develop when the other conditions are present
96
How do tropical storms form?
97
What's the spatial distribution of tropical storms?
98
How is the magnitude of tropical storms measured?
- Measured on the Saffir-Simpson Scale (1-5) based on wind speed (power of the storm)
99
What's the frequency of tropical storms?
- Tropical storms form in the northern hemisphere from June-November, and the southern hemisphere from November-April
- The majority don’t develop into strong storms, and don’t reach land
- Tropical storms that are higher in magnitude and reach land, are thought to be increasing in frequency
100
What's the regularity of tropical storms?
- Tropical storms are irregular because although they occur in the same areas, their path doesn’t follow a set route – the route taken is dependent on the storm, and the climatic conditions
101
What's the predictability of tropical storms like?
- Tropical storms form away from land, meaning satellite tracking of cloud formations and movement can be tracked , and the general route can be predicted
- The closer the hurricane gets, the easier it is to predict
- Storm surges can also be predicted, based on the pressure and intensity of the storm
- From past storms and climatic trends, the probability of a storm hitting an area can also be predicted – scientists have predicted how many years it will take for a tropical storm to hit certain areas
102
Hazards caused by tropical storms - high winds
- Winds reach over 300km/h, and are therefore very strong
- Hurricane winds are strong enough to blow a house down, and also blow heavy debris at high speeds, which can cause damage and injure anyone who comes into contact with them
103
Hazards caused by tropical storms - flooding
- Coastal/river flooding from storm surges and heavy rain
- River flooding also sends more floodwater to other places, which can cause areas outside of the tropical storm’s path to flood
104
Hazards caused by tropical storms - landslides
- Landslides occur when soils become heavy due to saturation from heavy rainfall
105
Hazards caused by tropical storms - storm surges
- Large rise in sea levels, due to low pressure and high winds, pushing water towards the coast
106
What are the primary impacts of storm hazards?
- Environmental - beaches eroded, sand displaced, coastal habitats such as coral reefs destroyed
- Economic - businesses destroyed, agricultural land damaged
- Social - drowning, debris carried by high winds can injure or kill, buildings destroyed
- Political - government buildings destroyed
107
What are the secondary impacts of storm hazards?
- Environmental - rivers flooding, saltwater contamination, animals displaced e.g. alligators, water sources change course due to blockages
- Economic - rebuilding and insurance payout, sources of income lost, economic decline
- Social - homelessness, polluted water supplies, spread of disease, food shortages
- Political - issues paying back international aid, pressure on government to act against global warming
108
What does prevention of storm hazards involve?
- In current climates and weather conditions, tropical storms can’t be avoided
- Strategies to mitigate climate change could prevent higher category storms
109
What does preparation for storm hazards involve?
- Awareness through education of what to do during a tropical storm
- Evacuation plans and training
- Satellite image tracking to manage the areas at risk
- Storm warning systems and TV broadcasts tracking the storm
110
What does mitigation of storm hazards involve?
- Search and rescue, immediate emergency aid, evacuation (short term)
- Strengthening the home through door barricades, roof strengthening, etc.
- Clearing loose debris before storms
111
What does adaptation for storm hazards involve?
- Move away from areas at risk
- Design buildings to withstand high winds and flooding
- Flood defences, such as houses on stilts, coastal walls, river levees, etc.
112
What are wildfires?
- Large, uncontrolled fires that quickly spread through vegetation
- Recent temperature increases have caused an increase in the number of wildfires, and an increase in the length of wildfire seasons
- There are also arguments that, despite climate change, wildfires aren’t increasing everywhere
- Studies have shown that this is somewhat true – between 1998 and 2015, globally burned areas declined by around 24%
- However, this may also be down to agricultural productivity and land use change, as there are less areas that can be burned (less forests)
113
Conditions favouring intense wildfires - vegetation type
- Thick, dense vegetation allows fires to spread quickly and easily
- Trees and thick bushes lead to more intense wildfires
- Grasslands don’t burn as intensely
- Vegetation with flammable oils (e.g. eucalyptus) causes more intense fires
114
Conditions favouring intense wildfires - fuel characteristics
- Vegetation should be dry to allow it to catch fire
- Finer vegetation causes fires to spread quicker, but larger, thicker forms of vegetation burn for longer and more intensely
115
Conditions favouring intense wildfires - climate
- Wildfires occur in climates that have enough rainfall to have sufficient plant growth, but enough dry spells and droughts to dry out the fuel
- Areas with dry seasons allow for intense wildfires
- Wind also causes fire to spread quicker (e.g. the Santa Ana Winds and Diablo Winds in California)
- El Nino (warm phase) and La Nina (cold phase) affect wildfires
116
How do fires spread quickly?
- Fires spread quickly on hills, as the heat rises
- Fires can also ‘jump’ across rivers, and into areas due to lit debris, which causes it to spread
117
What are the three types of wildfire?
- Crown fires
- Surface fires
- Ground fires
118
What are crown fires?
- Burn the entire tree from bottom to top
- Most dangerous and destructive type
119
What are surface fires?
- Only burn leaf litter
- Easy to extinguish
120
What are ground fires?
- Burn the dry peat or vegetation beneath the surface
- Move slowly through dried underground - Difficult to put out
121
What are the human causes of wildfires?
- Lit Cigarettes
- BBQs
- Agriculture
122
What are the natural causes of wildfires?
- Lightning (biggest cause)
- Volcanoes
123
What are the primary impacts of wildfires?
- Environmental - air pollution from ash, water pollution, habitats destroyed, toxic gases released, loss of biodiversity, damage to soil structure and nutrient content
- Economic - businesses destroyed, agricultural land damaged, cost of fighting fires, loss of crops, timber, and livestock
- Social - people killed or injured, homes destroyed (urban expansion into rural areas means more homes are at risk), people go missing during evacuations
- Political - government buildings destroyed
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What are the secondary impacts of wildfires?
- Environmental - removal of invasive species and stimulating seed germination, migration patterns of animals affected, increased CO2, increased flood risk, some species of plant can’t reproduce without fire
- Economic - high cost of rebuilding and insurance pay-out, sources of income lost, tourism sector decline, planes cancelled, unemployment
- Social - homelessness, food shortages after destroyed agricultural land, health problems from smoke inhalation, displacement
- Political - international aid, pressure on government to take more action on global warming
125
What are short term responses to wildfires?
- Emergency response teams try to put the fire out
- Warnings shared via social media, TV, and radio
- Fires can be diverted away from settlements
- Evacuation
- Spraying water onto the roofs of houses to prevent embers igniting them
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What does preparation for wildfires involve?
- Households write an emergency plan and buy emergency supplies of food, water, and medication
- Defensible space established around homes in vulnerable areas
- Authorities make emergency shelters
- Community preparedness in the form of early detection and suppression of wildfires. This is helped by trained rural firefighting teams staffed by volunteers
- Warnings are released using social media, TV, and radio
- A Red Flag Warning is used in the USA when weather conditions are perfect for wildfires to occur
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What does prevention of wildfires involve?
- Public awareness can prevent the ignition of wildfires – Smokey Bear is a 70-year-old US mascot used to provide information on preventing wildfires
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What does mitigation of wildfires involve?
- To immediately mitigate the effects, the fire must be extinguished or diverted
- Long-term mitigation strategies work to reduce the impacts of wildfires before they occur
- Controlled burning
- Fire breaks
- Those who live in areas at risk can mitigate the effects of wildfires by ensuring that their homes don’t contribute to the spread e.g. keeping flammable objects at least 30 ft away from the house
- To limit the effects of toxic gases and material contaminating the ecosystem, homes can be built using materials that won’t produce harmful substances when burnt
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What does controlled burning involve?
-Small-scale, controlled fires that remove flammable material, so less fuel is available for the wildfire to spread
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What are fire breaks?
- Gaps in vegetation created to limit the spread of wildfires
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What does adaptation for wildfires involve?
- Adapting lifestyles to decrease contribution to CO2 levels
- Fatalistic outlook – wildfires are natural meaning we have no control over them
- Many believe that it’s not worth the money or resources to extinguish wildfires if they’re only going to happen again
- There are ecological benefits of wildfires, supporting the idea that we should adapt to them and let them burn – they eradicate disease and stimulate seed germination
A Level Geography - Paper 1
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