Hazards Flashcards

(118 cards)

1
Q

forms and nature of natural hazards

geophysical

A

caused by land processes

including earthquakes, landslides, volcanic eruptions and tsunamis

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2
Q

forms and nature of natural hazards

atmospheric

A

caused by climatic processes

include tropical cyclones, storms, draughts, extremes of hot/cold weather and wildfires

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3
Q

forms and nature of natural hazards

hydrological

A

caused by water movement

include floods and avalanches

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4
Q

hazard perception

A

some believe they will never experience a particular hazard, others adapt their lifestyle to minimise risk and others accept that hazards are beyond their control

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5
Q

economic/social/cultural factors determining hazard perception

A

wealth: rich can afford to move away from hazard/built homes resistant
religion: hazards as acts of god to punish
education: better education = better understanding of risks/able to reduce or mitigate impacts
past experience
personality: fear/excitement

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6
Q

human responses

fatalism

A

hazards cannot be avoided so they must just be accepted

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7
Q

human responses

prediction

A

working out when and where a hazard might occur which allows people to respond to it by evacuating therefore reducing impacts

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8
Q

human responses

adaption

A

reducing impacts through adaption e.g. adding earthquake resistant features to buildings

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9
Q

human responses

mitigation

A

reducing the impacts of a hazard, e.g. through adaption or prediction

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10
Q

human responses

management

A

governments may coordinate responses to a hazard to manage it correctly

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11
Q

human responses

risk sharing

A

sharing the costs of reducing a hazard, benefits or it or the costs of not preventing it, e.g. insurance

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12
Q

responses in relation to hazard incidence

magnitude/intensity

A

how powerful the hazard is

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13
Q

responses in relation to hazard incidence

level of development

A

less developed countries may lack the wealth and technology to manage hazards effectively

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14
Q

the park model of human responses to natural disasters

stages

A

pre disaster: normal, before event

disruption: during/directly after disaster, destruction of property/loss of life
relief: saving people/preventing further damage
rehabilitation: resolve longer term probs, temporary shelter/aid
reconstruction: re building houses/infrastructure, same standard/higher

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15
Q

the hazard management cycle

A

mitigation: before or after, minimising impacts e.g. flood defences or fire resistant roofs
preparedness: planning how to respond, e.g. warning systems
response: how people react when a disaster occurs e.g. emergency services rescuing
recovery: getting the effected area back to normal, e.g. repairing/rebuilding houses.

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16
Q

the park model of human responses to natural disasters

A

shows how responses progress during a disaster which may help planners predict what resources will be needed at each stage
also help planners to prepare for future hazard events, mitigating impacts

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17
Q

natural hazards potential impacts

A

emergency responses, e.g. evacuating area

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18
Q

disaster definition

A

when a hazard actually seriously affects humans

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19
Q

hazard defintion

A

something that is a potential threat to human life or property
natural hazards are caused by natural processes

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20
Q

risk definition

A

the likelihood that humans will be seriously affected by a hazard

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21
Q

vulnerability definition

A

how susceptible a population is to damage caused by a hazard

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22
Q

responses in relation to hazard incidence

distribution

A

the areal extent of a hazard

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23
Q

responses in relation to hazard incidence

incidence

A

how often a hazard occurs

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24
Q

the park model of human responses to natural disasters

A

shows how responses progress during a disaster which may help planners predict what resources will be needed at each stage
also help planners to prepare for future hazard events, mitigating impacts

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25
what is the earth's structure
inner core, outer core, mantle, asthenosphere, lithosphere, crust
26
about the core
inner: solid ball containing iron and nickel outer: semi molten containing iron and nickel
27
about the mantle
most made of silicate rocks nearest core: quite rigid layer above that: asthenosphere, semi molten top: rigid
28
about the crust
rigid top part of mantle + crust: lithosphere continental crust: thicker and less dense oceanic: thinner and more dense
29
the earth's internal energy sources
the main source of internal energy is the core and the mantle as they are very hot some of the heat is left over from when the world was formed and some comes from radioactive decay of elements such as uranium
30
plate tectonic theory: | tectonic plates
the lithosphere is divided into slabs called tectonic plates which move in relation to each other the places where the plates meet are called plate boundaries/plate margins
31
plate tectonic theory: | ridge push/gravitational sliding
at constructive plate margins magma rises to the surface and forms new crust which is very hot, this heats the surrounding rocks which expand and rise above the surface of the surrounding crust forming a new slope the new crust cools and becomes denser, gravity causes the new crust to move downslope, away from the plate margin this puts pressure on the tectonic plates causing them to move apart
32
plate tectonic theory: | slab pull
at destructive plate margins denser crust is forced under less dense crust the sinking of the plate edge pulls the rest of the plate towards the boundary
33
plate tectonic theory: | convection currents
the earth's mantle is hottest closest to the core so lower parts of the asthenosphere heat up, become less dense and slowly rise as they move towards the top they cool down, become more dense and slowly sink these circular movements of semi molten rock are known as convection currents they create drag on the case of the tectonic plates, causing them to move
34
plate tectonic theory: | sea floor spreading
as tectonic plates diverge magma rises up to fill the gap created, then cools to form new crust over time the new crust is dragged apart and even more new crust forms between it when this happens at a plate margin under the ses the sea floor gets wider: sea floor spreading it creates mid ocean ridges: ridges of higher terrain on either side of the margin
35
what are destructive plate margins
when two margins are moving towards each other (converging)
36
what are constructive plate margins
two plates are moving apart (diverging) the mantle is under pressure from the plates above, when they move apart pressure is released at the margin the release of pressure causes the mantle to melt producing magma
37
what are conservative plate margins
where two plates are moving past each other, the two plates get locked together in places and pressure builds up
38
conservative plate margins characteristic processes seismicity and vulcanicity
pressure build up causes plates to jerk past each other or to crack forming fault lines releasing energy as an earthquake e.g. pacific and north american plates: san andreas fault line in california
39
magma plumes
a magma plume is a vertical column of extra hot magma that rises up from the mantle volcanos form above magma plumes as the tectonic plate moves the volcanic activity subsides but the magma plume remains in the same place causing a chain of volcanic islands, e.g. hawaii
40
magma plumes
a magma plume is a vertical column of extra hot magma that rises up from the mantle volcanos form above magma plumes the magma plume remains stationary over time but the crust moves above it the volcanic activity in the part of the crust the was above the magma plume decreases as it moves away new volcanos form in the part of the crust that is now above the magma plume as the crust continues to move a chain of volcanos is formed e.g. hawaii
41
destructive plate margins | oceanic-continental
where continental crust and oceanic crust converge, the more dense oceanic crust is subducted under the less dense continental crust this forms a deep sea trench fold mountains also form where the plates meet, made up of sediments that have accumulated on the continental crust which are folded upwards along with the edge of the continental crust the oceanic crust is heated by friction and contact with the upper mantle which melts it into magma the magma is less dense than the continental crust and will rise back to the surface to form volcanos as one plate moves under the other they can get stuck which causes pressure to build up, when the pressure becomes too much the plates jerk past each other causing an earthquake
42
destructive plate margins | oceanic-oceanic
most of the same processes as oceanic-continental, denser of the two will be subducted forming a deep sea trench and triggering earthquakes and volcanos volcanic eruptions that take place underwater (when oceanic-oceanic converge) they create island arcs, clusters of islands that sit in a curved line, e.g. mariana islands
43
destructive plate margins | continental-continental
neither is subducted so no
44
destructive plate margins | continental-continental
neither is subducted so no volcanos but pressure build up between them can cause earthquakes fold mountains form e.g. himalayas
45
volcanic hazards | at constructive margins
basaltic lava: very hot and low viscosity so flows easily and quickly, eruptions are frequent and go on for a long time but they're not violent if the margin is underwater magma rises to fill the space left by plates moving apart forming ocean ridges if the margin is on land as plates pull apart forming rift valleys they become thinner and magma is able to break through the surface
46
volcanic hazards | at destructive margins
adesitic and rhyolitic lavas are formed here, they are cooler and more viscous than basaltic lava so they flow less easily. andesitic and rhyolitic lavas usually erupt intermittently and the eruptions are short lived at subduction zones where one plate is pulled underneath another, melting of the plate forms magma, which rises to the surface as volcanos. because the lava is viscous, it forms blockages in volcanic events causing pressure to build. the blockage is cleared by a violent eruption
47
volcanic hazards | at hot spots
few volcanos form away from plate margins at hot spots above magma plumes most hot spots have basaltic lava that flows quickly, forming volcanos with gentle slopes (shield volcanos)
48
volcanic hazards primary hazards pyroclastic flows/nuee artendes
a mixture of super heated gas, ash and volcanic rock that flows down the side of a volcano, travels and high speed and a flows long way because they travel fast and happen with relatively little warning, pyroclastic flows can cause widespread death and destruction through e.g. burning and burial
49
volcanic hazards primary hazards lava flows
can flow from a volcanic vent down the side of a volcano the speed of the flow and distance travelled depends on the temp and viscosity of the lava as well as the steepness of the slope most flows are relatively slow so people have time to evacuate areas that will be affected, however laval flows destroy anything in their path including buildings and vegetation, by burning, burying or knocking down
50
volcanic hazards primary hazards volcanic gases
lava contains gases such as carbon dioxide and sulfur dioxide which are released into the atmosphere when a volcano erupts some of these gases can be harmful to humans and animals if they're breathed in e.g. sulfur dioxide can cause breathing difficulties
51
volcanic hazards primary hazards pyroclastic and ash fallout
pyroclastic fallout is material that has been ejected from a volcano during an eruption and falls back to the ground when fallout consists of mostly ash, it is called ash fallout range of sizes, from large pieces of rock to ash particles, can travel thousands of kms, heavier particles are deposited earlier than light ones so material ends up well sorted larger pieces of falling tephra can damage buildings and kill or injure people. finer material can form a layer several metres thick which can kill vegetation, hinder road and rail transport and cause buildings to collapse. ash can be harmful if it is breathed in
52
volcanic hazards secondary hazards mudflows/lahars
occur when volcanic material mixes with large amounts of water from rainfall or ice melt, flows move quickly and can travel 10's of kms mudflows can bury or destroy natural habitats, settlements and infrastructure
53
volcanic hazards secondary hazards acid rain
volcanic gases can react with water vapour in the atmosphere which then falls as acid rain, e.g. sulfur dioxide reacts with water to form weak sulfuric acid this can damage ecosystems and can also cause stone and metal to deteriorate damaging buildings, bridges and statues etc
54
volcanic hazards | magnitude
small slow lava flows to huge eruptions of lava, ash and gas magnitude can be measured using the volcanic explosivity index which grades volcanos 0-8 based on the amount of material ejected and how high material is blasted
55
volcanic hazards | frequency
how often they erupt, less frequent are larger in magnitude and more damaging
56
volcanic hazards | randomness vs regularity
some erupt at regular intervals whereas some remain dormant for years then erupt several times in quick succession
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volcanic hazards | predictability
the regularity with which a volcano erupts can help scientists to predict when it might erupt again. they also monitor tiny earthquakes and changes in the shape of the volcano which suggests that an eruption is imminent
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volcanic hazards | primary impacts
a direct result of the eruption, e.g. people being killed by falling tephra
59
volcanic hazards | secondary impacts
occur as a result of the primary impacts e.g. pyroclastic flows can melt glaciers and cause flooding
60
volcanic hazards impacts social
people are killed buildings and infrastructure destroyed by pyroclastic flows and fallout pyroclastic flows and lava flows can start fires that damage buildings mudflows and flooding from ice melt can cause further damage and deaths
61
volcanic hazards impacts environmental
ecosystems damaged/destroyed by flows and fallout of volcanic material acid rain can cause acidification of aquatic ecosystems, killing some plants and animals. also damages leaves of trees and removes nutrients from the soil, damaging forests volcanic gases contribute to the enhanced greenhouse effect and can add to global warming clouds of ash and volcanic debris can reduce the amount of sunlight reaching earth, decreasing temperatures over large areas
62
volcanic hazards impacts economic
eruptions can destroy businesses and ash clouds can prevent aircraft flying and damage crops which damages the economy damage to buildings and infrastructure is expensive to repair eruptions and the scenery they form can attract tourists, boosting the economy
63
volcanic hazards impacts political
damage to agricultural land can cause food shortages, leading to conflict and political unrest governments may have to spend money on repairing damage to buildings and roads rather than hospitals and schools so countries may not develop as rapidly
64
volcanic hazards responses short term
normally occur immediately before, during or immediately after the hazard begins, includes evacuating people from areas at risk and providing emergency food supplies.
65
volcanic hazards responses long term
designed to reduce the impacts of future eruptions by managing risks
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volcanic hazards responses long term prevention
not possible to prevent a volcanic eruption | possible to prevent eruptions posing a risk to people, e.g. authorities prevent land around a volcano being developed
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volcanic hazards responses long term preparedness
when happens before an eruption to minimise risk or vulnerability, e.g. monitoring systems to predict when an eruption may occur and make plans for how they will evacuate people if an eruption is imminent authorities can stop people entering the area individuals can find emergency shelter/make emergency kits search and rescue teams or fire response units
68
volcanic hazards responses long term adaption
changing behaviour or surroundings to minimise risks amd maximise benefits of living near a volcano buildings can be strengthened to reduce the chance of collapse if a layer of ash lands on them people can capitalise on opportunities of living near a volcano e.g. by farming or working in the tourist industry
69
seismic hazards | earthquakes
the primary hazard associated with a seismic event caused by tension that builds up at all 3 types of plate margin when the plates jerk past each other it sends out shockwaves; these shockwaves are the earthquake shockwaves spread out from the focus, could be the fault line. near the focus the waves are stronger and cause more damage the epicentre is the point on the earth's surface where the earthquake is felt first, it is directly above the focus earthquakes cause the ground to shake and sometimes rupture along the fault
70
seismic hazards | tsunamis
large waves caused by the displacement of large volumes of water can be triggered by underwater earthquakes, they cause the seabed to move which displaces water. waves radiate out from the epicentre of the earthquake. the greater the movement of the sea floor, the greater the volume of water displaced and the bigger the wave produced usually more powerful if it starts closer to the coast because waves lose energy as they move towards land waves travel very fast in deep water so they can hit the shore without much warning meaning they can cause a high death toll
71
seismic hazards | landslides and avalanches
shaking of the ground can dislodge rock, soil, or snow causing landslides or avalanches that move downslope quickly shaking can also loosen ground material, making it easier for water to infiltrate. the weight of extra water may trigger a landslide even after ground shaking has stopped
72
seismic hazards | soil liquefaction
when soil is saturated with water, the vibrations of an earthquake can cause it to act like a liquid this makes the soil weaker and easier to deform so it is more likely to subside, especially where it has a heavy weight on top of it, e.g. a building
73
the nature and magnitude of an earthquake | margin type
biggest earthquakes occur at destructive plate margins the subduction of a plate causes massive pressure to build up causing a huge earthquake when its released earthquakes at constructive margins tend to be lower magnitude than destructive or conservative
74
the nature and magnitude of an earthquake | rate of movement
tectonic plates move in relation to each other at different rates, 1-15cm per year no clear relationship between rate of movement and earthquake magnitude
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the nature and magnitude of an earthquake | depth of focus
the focus can be close to earth's surface or deep below it deep focus earthquakes tend to be higher magnitude than shallow focus earthquakes. however, deep focus earthquakes generally do less damage than shallow focus earthquakes because shock waves generated deeper in the the earth have to travel further to reach the surface which reduces their power
76
seismic hazards | magnitude and frequency
100's of low magnitude earthquakes happen every day, earthquakes of high magnitude occur much less often, the number of earthquakes globally varies year to year
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seismic hazards | randomness vs regularity
occurrence is largely random
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seismic hazards | predictability
scientists can monitor the movement of tectonic plates to predict which areas are at risk from seismic hazards however it is currently impossible to tell when an earthquake will strike a particular place and what magnitude it is likely to be
79
seismic hazards impacts social
buildings collapse, killing and injuring people and leaving others homeless earthquakes and liquefaction cause gas and power lines to break, starting fires that kill more people. broken pipes cause flooding and lack of water makes it hard to put out fires lack of clean water can cause disease to spread tsunamis can flood large areas killing people and causing widespread damage to property
80
seismic hazards impacts environmental
industrial units including powerplants can be damaged by earthquakes and tsunamis causing leaks of chemicals or radioactive material that damages the environment fires started by damaged gas and electricity lines can destroy ecosystems tsunamis can flood freshwater ecosystems, killing plants and animals and salinising water and soil
81
seismic hazards impacts economic
earthquakes can destroy business premises through ground shaking and liquefaction, this damages the economy damage to industry may mean that the country has to rely on expensive imports of goods and energy damage to buildings and infrastructure can be very expensive to repair
82
seismic hazards impacts political
shortages of food water and energy can cause conflict and political unrest governments may have to borrow money to repair damage, putting the country in debt money that is earmarked for development may have to be spent on repairing damage rather than development
83
seismic hazards responses prevention
not possible to prevent most seismic hazards sometimes possible to prevent them posing a risk, e.g. authorities can prevent land that is prone to liquefaction from being build on or build giant sea walls to prevent tsunamis hitting land
84
seismic hazards responses preparedness
earthquake warning system individuals and businesses have plans of how to respond, e.g. staying away from buildings if possible, finding a strong door frame or desk to shelter under tsunami warning systems and evacuation routes well signposted search and rescue teams or fire response units
85
seismic hazards responses adaption
adapt behaviour or surroundings to minimise risks buildings designed to withstand earthquakes, e.g. strong or flexible materials buildings designed to reduce vulnerability to tsunamis e.g. tall strong buildings allow people to escape the tsunami quickly, and buildings with raised, open foundations are less likely to be damaged
86
how are earthquakes measured
1) the richter scale: measures how powerful the shaking is, doesnt have an upper limit and is logarithmic (mag of 5 is ten times greater than mag of 4) major earthquakes 7+ 2) the moment magnitude scale: based on total amount of energy released, logarithmic and has no upper limit, more accurate than richter scale 3) the mercalli scale: measures the impact of the earthquake using observations of the event, e.g. reports and photos, scale is 1-12
87
what is a tropical storm
huge spinning storms with strong winds and torrential rain they develop over warm water, as warm moist air rises and condenses, it releases energy that increases wind speed they are circular in shape, hundreds of kms wide and last 7-14 days they spin anticlockwise in the northern hemisphere and clockwise in the southern hemisphere at the centre of the storm there is an area of low pressure called the eye rising air spirals around the eye in the eyewall, causing strong winds near the top of the storm there is an outflow of moisture laden air so cloud cover extends for a long distance either side of the eye
88
how are tropical storms formed
form in the tropics because the water is warm enough occur in the caribbean sea: hurricanes the bay of bengal: cyclones the china sea: typhoons and in northern autralia tropical storms lose strength when they move over land because their supply of warm moist air is cut off they initially move westwards due to easterly winds in the tropics e.g trade winds move cyclones west across the atlantic ocean they move away from the equator because of the coriolis effect
89
how is storm magnitude measured
using the saffir simpson scale which is based on wind speed. category 5 is the strongest and 1 is the weakest also estimates how much damage a storm of a given magnitude will do, from limited to catastrophic
90
storm hazards | frequency
tropical storms are quite frequent, around 100 per year some never reach land so never develop into a major hazard storms are more frequent in the northern hemisphere between june and november and more frequent in the southern hemisphere between november and april
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storm hazards | regularity
lots of factors that affect when and where a tropical storm will form and where it will land so the hazards created by storms are largely irregular follow no clear spatial or temporal pattern
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storm hazards | predictability
certain cloud formations in tropical areas can be identified from satellite imagery and used to tell when a tropical storm is forming. the storm can then be tracked using satellite imagery and models, helping scientists work out when and where it might hit land. the path of a tropical storm can therefore be predicted fairly accurately
93
what are storm hazards
high winds: 300km/h+, destroy buildings, uproot trees, carry debris long distances and smash them into other objects storm surges: a large rise in sea level caused by high winds pushing water towards the coast and by the low pressure of a storm heavy rain: warm moist air cools and condenses it causes torrential rain flooding: heavy downpours cause river discharge to increase suddenly causing rivers to overtop their banks and flood the surrounding area. heavy rain and storm surges can also cause flooding in coastal areas landslides: water infiltrates soil and rock making it less stable and increasing the risk of landslides
94
storm hazards impacts social
people may drown/be injured or killed by debris houses are destroyed so people are left homeless electricity cables are damaged and supplies are cut off flooding causes sewage overflows, contaminating water the lack of clean water can help diseases spread damage to agricultural land can cause food shortages
95
storm hazards impacts political
people may blame authorities for shortages of food/water/energy, leading to conflict and political unrest expensive repairs limit the amount of money that can be spent on development
96
storm hazards impacts economic
buildings and infrastructure are expensive to rebuild business are damaged/destroyed so cant trade agricultural land is damaged, affecting commercial farming
97
storm hazards impacts environmental
beaches are eroded and coastal habitats e.g. coral reefs are damaged. sediment deposited in aquatic ecosystems may damage fish breeding grounds environments are polluted e.g. by salt water, oil and chemicals spilled from damaged factories landslides can block watercourses so they change course
98
storm hazards long term responses prevention
storms cannot be prevented but they can be studied to help scientists understand which areas are most likely to be affected which means that future developments can be planned to avoid high risk areas
99
storm hazards long term responses preparedness
emergency services train and prepare for disasters, governments plan evacuation routes to get people away from storms quickly and educate people about how to prepare about how to prepare for a storm e.g. stock piling water and food and boarding up windows
100
storm hazards long term responses adaption
buildings can be designed to withstand tropical storms e.g. by using reinforced concrete or by fixing roofs securely so they're not blown off buildings can also be put on stilts so they're safe from floodwater flood defences can be built along rivers and coasts
101
what are wildfires
uncontrolled fires that destroy forests, grassland, and other areas of vegetation. usually occur in rural areas but if they reach inhabited areas they will also destroy agricultural land and settlements
102
types of wildfire | ground fire
where the ground itself burns | it is a slow, smouldering fire with no flame and little smoke
103
types of wildfire | surface fire
where leaf litter and low lying vegetation burn, fire can be low or high intensity
104
types of wildfire | crown fire
where fire moves rapidly through the canopy (top layer of vegetation) fires are more likely to be intense and fast moving
105
conditions for an intense wildfire | vegetation type
thick undergrowth or closely spaced trees allow fire to travel easily eucalyptus and pine contain a lot of oil so burn easily eucalyptus trees shed strips of their bark which helps the fire to spread quickly
106
conditions for an intense wildfire | fuel characteristics
fine, dry material catch fire and burn most easily | large amounts of fuel that form a continuous cover will help the fire burn for longer and spread
107
conditions for an intense wildfire | climate and recent weather
rainfall must be sufficient for vegetation to grow so there's plenty of fuel the area usually has a distinct dry season when rainfall is low for a significant time. warm, dry weather causes water in the vegetation to dry up so its more flammable strong winds provide more oxygen to help the fire burn and spread burning embers
108
conditions for an intense wildfire | fire behaviour
creeping fire moves across the ground surface fairly slowly whereas a running fire spreads rapidly and is more intense fires can throw out burning debris (firebrands) that help the fire spread and become more intense
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wildfires causes natural
fuel, oxygen, heat | heat: lightening especially without rain, volcanic eruptions produce hot lava, gas or ash which starts fires
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wildfires causes human
fuel, oxygen, heat most fires are started by people this can be accidental, e.g. by dropping cigarettes, allowing campfires or barbecues to get out of control, pr if fireworks/sparks from machinery land in vulnerable areas can also be started on purpose: arson
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wildfires impacts social
people killed or injured if they don't evacuate in time homes destroyed so people left homeless destroy powerlines and damage reservoirs, leaving people without electricity or clean water health problems e.g. smoke inhalation
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wildfires impacts political
governments can face criticism when wildfires have severe impacts governments may have to change their forest management practices to reduce the risk of wildfire e.g. clearing vegetation to limit fuel
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wildfires impacts economic
wildfires destroy businesses, leading to loss of jobs and income insurance premiums increase drastically after a wildfire cost of fighting wildfires is huge wildfires may discourage tourists from visiting an area, reducing income
114
wildfires impacts environmental
habitats are destroyed. some species may not return to an area after a wildfire, changing the ecosystem soils are damaged as fire removes organic matter smoke causes air pollution and water sources can be contaminated with ash some ecosystems rely on wildfires to clear dead vegetation and some plant seeds need mire to germinate
115
wildfires responses short term
trying to put out the fire, diverting it away from settlements, evacuating people from areas at risk and spraying water on to roofs of houses to prevent embers from setting them alight
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wildfires responses prevention
public education about the risks of using campfires and barbecues in vulnerable areas authorities may provide fire beaters to put small fires out before they spread
117
wildfires responses preparedness
households having an emergency plan and emergency supplies of food, water and medicine or authorities making emergency shelters available
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wildfires responses adaption
non flammable building materials and creating fire breaks (gaps in trees) around settlements to stop fire spreading