seismic and storm hazards Flashcards
1
Q
what is an earthquake?
A
- a sudden or violent movement within the earths crust followed by a series of shocks
2
Q
how is an earthquake formed?
A
1) earthquakes are caused by the tension that builds up at all three types of plate margins ( destructive, constructive and conservative )
2) when the plates jerk past each other it sends out shockwaves, due to the release of energy
3) the shockwaves spread out from the focus, the focus doesn’t have to be a single point - e.g. it could be along a fault line, near the focus the waves are stronger and cause more damage
4) the earthquake is felt first at the epicentre
5) earthquakes cause the ground to shake, and sometimes to rupture along the fault
3
Q
what is the epicentre?
A
- the point on the earths surface above the focus, where the earthquake is felt first
4
Q
what is the focus?
A
- the place where the energy is released
- an earthquakes focus can be close to the earths surface or deep below it
- a deeper focus earthquake tends to have a higher magnitude that a shallow focus earthquake, however deep focus earthquakes do less damage than shallow as the shockwaves are generated deeper in the earth so have further to travel to reach the surface, so their power is reduced
5
Q
where are the biggest earthquakes located?
A
- the biggest earthquakes occur at destructive plate margins, where one plate is forced beneath another at the subduction zone, e.g. Benioff zone, they are very powerful and can occur under the sea
- the subduction of a plate causes massive pressure to build up, causing a huge earthquake when released
- earthquakes at constructive margins tend to be shallower and less powerful and can occur along the mid-Atlantic ridges away from people and land
- earthquakes at conservative plates are shallow and focused as continental plates drag past one another causing high compressions, meaning they are very powerful and can be severe if they occur in densely populated areas
6
Q
how can earthquakes be measured?
A
1) the Richter scale
2) the moment magnitude scale
3) the modified Mercalli scale
7
Q
what is a Richter scale?
A
- the Richter scale- measures the magnitude of an earthquake ( how powerful the shaking is ), it is logarithmic meaning an earthquake with a magnitude of 5 has an amplitude ten times greater than one with a magnitude of 4
8
Q
what is a moment magnitude scale?
A
- the moment magnitude scale- based on the total amount of energy released by an earthquake, it is more accurate than the Richter scale especially for large earthquakes so is more widely used
9
Q
what is a modified Mercalli scale?
A
- the modified Mercalli scale- measures the impacts of an earthquake using observations of the event ( e.g. reports and photos ), the scale is between 1 and 12 with 1 being an earthquake that’s only detected by instruments and 12 being an earthquake that causes total destruction
- it is easier to understand and shows the effects of the earthquake on people e.g. people awakening, movement of furniture or total destruction
10
Q
what are the 3 seismic shock waves?
A
1) primary pressure waves- these are the fastest and first waves to arrive at the surface
2) secondary / shear waves- these are slower than primary waves and reach the surface next, they have a higher frequency and can travel through the mantle
3) love waves- slowest waves and can cause the most damage as they move side to side
11
Q
how do we prevent an earthquake?
A
- the majority of seismic hazards cannot be prevented however:
- liquefaction of soils can be prevented through soil stabilisation ( gravel columns can be put in the ground )
- avalanches can be prevented through controlled explosions
12
Q
how can we prepare for earthquakes?
A
1) within homes, any heavy items,
( such as TVs, refrigerators and bookcases ) should be secured and breakable items stored at a low level
2) families should create a communication plat e.g. WhatsApp groups and establish emergency meeting routes and places
3) households should have an emergency supply kit to last a few days containing essential items, such as food, water, clothing, bedding, a first aid kit, toilet paper, a torch, a radio etc.
4) insurance such as house and health insurance should be updated in case of damage to property or injury
5) building structures need to be solid e.g. earthquake proof buildings, so they sway, as well as shutters on windows and shock absorbers to prevent buildings from collapsing
- building materials such as wood should be used as it can flex unlike brick
13
Q
how can we mitigate against an earthquake?
A
1) early warning systems- these give people a short amount of time to put themselves into a safer position for when the earthquake hits e.g. in Japan the ‘earthquake early warning’ system aims to reduce earthquake-related damage by slowing down trains immediately, controlling lifts and enable people to stop, drop and wait
2) hazard-resistant structures- designed to be earthquake resistant e.g. putting shock absorbers in the foundations that will allow some movement of the building without structural failure
14
Q
how does adaption relate to the economic development of a country?
A
- long term change in people’s behaviour depends on levels of economic development, education and national and regional priorities
- e.g. countries such as the USA and Japan are generally more able to adapt their environment than those in low income countries
15
Q
how do we adapt against an earthquake?
A
1) land use planning- includes identifying areas most at risk from seismic events and regulating land-use planning for those areas
- putting key buildings, such as schools and hospitals in low-risk areas and open spaces, such as parks in more high-risk areas
- including open spaces in plans to allow for safe areas, away from fires and aftershock damage to buildings
2) emergency services adapting- must adapt their organisation and planning to deal with seismic events e.g. heavy lifting gear needs to be available and emergency service personnel should be first-aid trained to deal with any causalities
3) having a substantial amount of search and rescue and planning before hand on who goes where
16
Q
what is the case study for seismic events?
A
- Lombok earthquake in Indonesia 2018
- this is when a series of seismic events took place between the 29th of July and the 19th of august 2018
17
Q
where is Lombok located?
A
- the island of Lombok in Indonesia is part of the chain of Lesser Sunda Islands, along with Bali to the west and Sumbawa to the east
18
Q
why is Indonesia a high risk place for seismic hazards?
A
- as Indonesia is a meeting point of several tectonic plates and is one of the most seismically active places on earth
- it is a typical island arcs where the Indo-Australian plate is moving northward towards, and subducting under, the south easterly moving Eurasian plate, which moves approximately six centimetres per year
- most of the earthquakes affecting Indonesia happen along the Sunda Arc subduction zone
19
Q
what are the tectonic processes occurring near Lombok?
A
1) this earthquake happened at a destructive plate margin where there is the subduction of the Indo-Australian plate under the Eurasian plate, forming ocean trenches, this subduction zone is named the ‘Wadati-Benioff Zone’
2) volcanoes can occur here as the partial melting of the continental plate, causes magma, which rises as it it less dense than the surrounding rock. when the volcano reaches above sea level island arcs form
3) earthquakes form here due to the friction of the two plates moving towards each other, which also forms a build up of energy that is released when the plates are past one another, causing seismic vibrations / waves
20
Q
what were some events that happened during the Lombok earthquakes and how did Indonesia respond to them?
A
29th July 2018 a 6.4 magnitude earthquake strikes Lombok- the Indonesian Red Cross allocates money from their emergency fund to enable them to meet the humanitarian needs of 1,000 households ( 4000 people )
30th July 2018- the local state governor declared a three-day state of emergency
5th August 2018 a second stronger earthquake of 7.0 magnitude and depth of 15km strikes Lombok- the Indonesian Red Cross launched an emergency appeal for funds to assist 80,000 people affected by earthquakes in Lombok for 18 months
September 2018- an earthquake hits elsewhere in Indonesia and funds and help are diverted away from Lombok
8th November 2018- the emergency appeal asks for further funds to deliver assistance to 20,000 households in Lombok for 30 months
21
Q
what were the major impacts of the Lombok earthquake?
A
the Indonesian National Board for Disaster Management reported that:
- 564 people died
- 1,584 people were injured
- over 445,000 people were in makeshift shelters
- over 129,000 houses were damaged
- over 432,000 persons had been displaced and were living in 2,700 displacement sites
- 458 schools were damaged
- the total cost of the damage was estimated to be around $600 million
22
Q
what are the primary hazards of an earthquake?
A
1) ground shaking- caused by shock waves travelling through the crust from the focus up to the surface and then radiating outwards
2) ground rupture- the visible breaking and displacement of the earths surface
23
Q
what are the secondary hazards of an earthquake?
A
- soil liquefaction
- landslides and avalanches ( slope failure as a result of ground shaking )
- tsunamis
24
Q
what are the environmental effects of primary seismic hazards?
A
- earthquakes can cause fault lines which destroy the environment
- liquefaction can occur which makes buildings unstable
25
what are the economic effects of primary seismic hazards?
- businesses are destroyed, so causes economic decline as people have no source of income
26
what are the social effects of primary seismic hazards?
- buildings collapse, killing/injuring people and trapping them
27
what are the political effects of primary seismic hazards?
- government buildings are destroyed
28
what are the environmental effects of secondary seismic hazards?
- radioactive materials and other dangerous substances leaked from power plants
- saltwater from tsunamis can flood freshwater ecosystems
29
what are economic effects of secondary seismic hazards?
- economic decline as businesses are destroyed ( tax breaks etc. )
- high costs of rebuilding and insurance pay out as sources of income are lost
30
what are the social effects of secondary seismic hazards?
- gas pipes rupture, starting fires which can kill
- water supplies are contaminated as pipes burst, spreading disease and causing floods
- tsunamis lead to damaging flooding
31
what are the political effects of secondary seismic hazards?
- political unrest from food and water shortages
borrowing money for international aid, so development of country decreases as money is earmarked for development may have to be spent on repairing damage
- can be initial chaos and 'lawlessness' e.g. looting
32
what happens during soil liquefaction?
- during an earthquake shaking causes soil particles to move
- in waterlogged conditions such as below the water table, a loss of shear strength occurs due to the particles losing contact with each other
- therefore, the soil behaves as a liquid and the soil loses the ability to support it's own weight and buildings tilt or even collapse
- on a slope liquefaction causes soil to move downwards
33
what is a tsunami and how is it formed?
- giant sea waves generated by shallow-focus underwater earthquakes involving movements of the sea bed, or landslides into the sea or volcanic eruptions, underwater debris and large landslides into the sea
- tsunamis have a long wavelength, sometimes over 100km, a low wave height ( under one metre ) and they travel at speeds of over 700km per hour
- 90% of the most damaging tsunamis occur in the pacific basin, generated at subduction-convergent plate margins
34
what is the formation of a tsunami?
1) tectonics upthrust in the form of earthquakes or floor volcanoes that cause vast dissipation of water
2) energy from the quake causes a train of simple, progressive waves to propagate over the ocean surface in ever-widening waves that reach speeds of 500 mph, as the wavelengths continue to grow
3) as the waves approach the coastline they slow down due to friction with the seabed, the velocity lessens but the amplitude increases
- wavelengths hit the shore and the outflow of water continues to cause damage
35
give an example of a major earthquake and it's effects.
- march 2011, off the Pacific Coast of the Tohoku region of Japan
- the earthquake occurred 70km offshore and had a magnitude of 9.0, the most powerful earthquake ever recorded in Japan
- triggered waves of 40 metres high
- nearly 16,000 dead and over 6000 injured
- over 300,000 people were made homeless
- an estimated economic cost of Japan being £235 billion
36
how do we prepare for a tsunami?
1) tsunami warning systems- this is when sea bed pressure sensors are used to detect the sea pressure
- these send information to a surface buoy, which constantly measures the pressure of the overlying water column to warn the population before the wave reaches the land
37
what are tropical storms?
- tropical storms are huge spinning storms with string winds and torrential rain that develop over warm oceans (27 degrees)
- most begin 8-20 degrees north and south
38
what is the structure of a tropical storm?
- tropical storms are circular in shape, hundreds of km wide and usually last 7-14 days, they spin clockwise in the northern hemisphere and anticlockwise in the southern hemisphere
- at the centre of the storm, there is an area of low pressure called the eye where the weather is calm
- rising air spirals around the eye in the eyewall, where there is high pressure, cause strong wind and condensing, sinking air causes bands of rain
- 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
39
where do most cyclones, hurricanes and typhoons form?
cyclones- Indian ocean
typhoons- north west
hurricanes- south east ( Caribbean )
40
what conditions do tropical storms have to be under to occur?
temperature- ocean temps must be around 26-27°C and at least 50 metres deep, warm water provides the storm with energy
air pressure- must be in areas of unstable air pressure, usually where areas of high pressure and low pressure converge, so that warm air rises more readily and clouds can form
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
rotation- tropical storms only form around the equator, but no less than 5 degrees on either side
41
what is the Coriolis effect?
- the effect of the earths rotation on weather events e.g. the storm spins because the earth is spinning; but there is no Coriolis effect at the equator
42
describe the formation of a tropical storm.
1) warm, moist air rises, leaving an area of low pressure below, this causes warm air from surrounding areas of higher pressure to move into this low pressure area and rise too
2) the warm air rises and cools condensing into a thunderstorm cloud
3) the whole system is spinning due to the Coriolis effect
4) the constant addition of energy from the warm air causes the storm to spin faster and generate higher wind speeds, at 39mph the storm is classed as a tropical storm
5) the eye of the storm is in the centre, this is an area spanning around 30 miles wide that is extremely low pressure, cool dry air descends in the eye, causing the weather to be calm and cloud free ( the more intense the storm the clearer the eye )
6) surrounding the eye is the eyewall ( the most intense and powerful area of the storm ), where warm, moist air rapidly rises with extremely high winds and torrential rain, when wind reaches 74 mph it becomes a hurricane / cyclone/ typhoon
7) when the tropical storm reaches the coast, the low pressure and high winds cause large amounts of sea water to be taken up and then released as a high wave called a storm surge
8) when the storm reaches land, it no longer has a supply of energy ( warm, moist air from the sea ) and the eye eventually collapses, and heavy rain can persist for days
43
what is a storm surge?
- when the high winds cause large amounts of sea water to be taken into the system and then released as a high wave known as the storm surge
44
how are tropical storms measured?
- this is a scale based on wind speed and the power of the storm
- it is a scale of 1-5
- the main limitations are that it only measures one specific factor, the wind, and does not measure storm surges, rain and so doesn't have an accurate measure of damage
45
how can we predict a tropical storm?
- 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, as storm surges can also be predicted based on the pressure and intensity of the storm
- scientists have also predicted how many years it will take for a tropical storm to hit certain areas due to past storms and climatic trends
46
how is the predictability of a tropical storm said to change over future years?
- there is not predicted to be an increase in tropical storms because 8-20 degrees north and south are not getting warmer very quickly, which is where tropical storms form
- there is predicted to be an increase in intensity (2-11% more intense), as they have more energy from the ocean warming
- the movement of the tropical storms across the earth is expected to slow down, so will remain over one area for longer and will increase damage when it hits landfall due to prolonged periods of rain and winds ( having a 20% increase in intensity )
47
what hazards are caused by tropical storm?
high winds- over 300km/h and therefore very strong, hurricane winds are strong enough to blow down houses, and also blow heavy debris at high speeds which can cause widespread damage
flooding- coastal/river flooding from storm surges and heavy rain, sends more floodwater to other places outside of the tropical storms path to flood also
landslides- due to soil becoming heavy when wet with high levels of rain
storm surges- large rise in sea levels caused by low pressure and high winds, pushing water towards the coast
48
what are the environmental effects of primary storm hazards?
- beaches can erode and sediment deposited in aquatic ecosystems may damage fish breeding grounds
- sand can be displaced
- coastal habitats such as coral reefs are destroyed
49
what are the economic effects of primary storm hazards?
- businesses destroyed, so no trade can happen
- agricultural land is lost, so commercial farming is affected
50
what are the social effects of primary storm hazards?
- drowning due to high levels of flooding
- debris carried by high winds can injure and kill
- buildings destroyed, leaving many displaced
51
what are the political effects of primary storm hazards?
- government buildings destroyed
52
what are the environmental effects of secondary storm hazards?
- river/flooding salt water contamination
- animals are displaced from flooding e.g. alligators
- water sources changing course due to blockages, leaving many homes without a water supply
53
what are the economic effects of secondary storm hazards?
- rebuilding insurance pay out
- sources of income are lost so there will be an economic decline
54
what are the social effects of secondary storm hazards?
- homelessness
- polluted water supplies, which increase the spread of disease
- food shortages from damaged land
55
what are the political effects of secondary storm hazards?
- issues paying back international aid
- people may blame the authorities for shortages of food, water and energy, leading to conflict and political unrest
- expensive repairs to buildings, infrastructure etc. limit the amount of money that can be spent on development
56
how can we prevent a tropical storm?
- in current climates and weather conditions, tropical storms cannot be prevented, but they can be studied and future developments can be planned to avoid high-risk areas
57
how can we prepare for a tropical storm?
- communities and authorities can make sure they are prepared e.g. emergency services can train people in preparation of the storm
- governments can plan evacuation routes
- educate people about how to prepare for a storm e.g. stockpiling water and food or boarding up windows
- storm warning systems and television broadcasts can track the storm e.g. by satellite images, weather balloons and supercomputers that analyse and compare historical data
58
give an example of how a country prepared for a tropical storm.
- Bangladesh is creating a programme where multiple organisations are providing many methods of warning e.g. posters
- this provides people with shelter built out of concrete and on stilts to reduce flooding
- rebuilding mangroves just inland from the coast to protect areas from storm surges, as it dissipates the energy
- having an early warning system based on modern weather radar stations
59
how do we mitigate against a tropical storm?
- provide immediate emergency aid and search and rescue beforehand
- evacuation
- strengthening the home through door barricades, roof strengthening etc.
- clearing loose debris before storms to reduce damage
- cloud seeding (blasting silver iodide into the atmosphere to produce rain)
- waterproofing outside buildings and securely fixing rooves
- specialist insurance
60
how can we adapt to a tropical storm?
- buildings can be designed to withstand tropical storms e.g. by using reinforced concrete or by fixing roofs securely
- flood defences can be put in place along rivers e.g. seas walls and levees
- land use planning such as building houses higher and not by the coast or on stilts
- using sandbags and window shutters
61
what are two examples of tropical storms?
- Hurricane Michael, USA 2018
- Typhoon Haiyan, Philippines 2013
62
describe and explain the path of hurricane Michael.
- the hurricane made landfall early in the afternoon of the 10th of October 2018, having briefly been a category 5 storm
- the storm travelled north-easterly due to the Coriolis effect in the northern hemisphere deflecting the storm to the right, making it come ashore on the coast of Florida near Mexico Beach, a small town with a population of 1000 people
- it then reduced in strength from a category 5 to a extra tropical storm, as it headed inland towards Georgia and parts of North and South Carolina, which has already been effected by Hurricane Florence earlier in the year
63
outline the potential geographic variation in vulnerability.
- the storm came ashore on the coast of Florida near Mexico beach, meaning the storm will have a stronger source of energy from the ocean so will increase their vulnerability and decrease quality of life
- the inland countries, such as Georgia and Carolina, could have had a decrease in deaths due to the storm losing power, however this could be proven inaccurate due to the previous hurricane that hit increasing their vulnerability as they will still be recovering
64
what were some of the social impacts of Hurricane Michael?
- there were 16 deaths across the states of Florida, Virginia, North Carolina and Georgia
- an additional 43 deaths were caused by falls during the post-storm clean up, traffic accidents and medical issues made worse by the hurricane
- roofs were ripped off and swept into the air
- two hospitals took severe damage, meaning people had little access to healthcare after the storm
- power cuts affected nearly 400,000 Floridians which is about 4% of the whole state
65
what are some of the economic impacts of Hurricane Michael?
- 45,000 structures were damaged with more than 1,500 destroyed including 2 hospitals
- in the town of Mexico Beach, 1,584 of the town's 1,692 buildings were damaged with 800 being destroyed
- $18.4 billion of the estimated total $25 billion damage occurred in Florida
- agriculture and forestry losses were about $3.87 billion, primarily in Florida and Georgia, impacted commercial farmers and trade
- in the US at least $6.23 billion was in insurance claims
66
what are some of the environmental impact of Hurricane Michael?
- flash flooding occurred that turned roads into rivers
- wind, storm surges and rain (floods) occurred
- trees uprooted and power lines were brought down
- major agricultural and forestry losses
67
what responses were carried out before the storm?
7th October 2018- residents were advised by the governor of Florida to prepare for the storm
8th October 2018- a mandatory evacuation is issued for three coastal countries, including Bay County
- schools were closed and the mayor of Panama City asked 2/3 of the county (120,000) residents to evacuate
9th October 2018- president Trump approves a major disaster declaration request for Florida, this included many aspects such as: access to federal resources and money for relief and recovery efforts
- a state of emergency is declared and plans for evacuation are made in Georgia
- emergency preparedness organisations, like direct relief, provided emergency medical packs to health facilities that were in the storms path
68
what responses were carried out after the storm?
- Bay County, Florida had to borrow more than $250 million to pay for the clean-up whilst it waited for reimbursement from state and federal government
- 1,500 national guard personnel were activated in the state of Georgia
- on the 11th of October 2018, president trump declared a major disaster in 5 countries, so countries were able to receive grant for house repairs, temporary shelter, loans for uninsured property losses and business loans
- he also signed an emergency declaration for Georgia, authorising funding for 75% of the cost of emergency protective measures and removal of storm debris
- the Federal Emergency Management Agency and several private and not-for-profit organisations established the Hurricane Michael Relief Network to provide direct relief to residents that were affected by the disaster
69
describe the track of Typhoon Haiyan.
- by 6th September 2013, the system was assessed as a category 5 or super-typhoon with wind speeds already reaching over 250 km/hr, with gusts reaching over 300 km/hr
- on the 7th November it made landfall as the most powerful typhoon ever recorded with the highest wind speeds reaching 315 km/hr
70
what were the human impacts of typhoon Haiyan that affected vulnerability in Tacloban?
- in recent years many Filipinos have moved in large numbers from the countryside areas to cities such as Tacloban looking for opportunities to work and make money
- this led to high densities of population and often overcrowded residential areas, which makes the people more vulnerable when events such as Haiyan occur
- many of the people have built poorly constructed houses on the flat land nearest to the sea, increasing vulnerability to storm surges and flooding
- poor people are unable to provide for themselves, so they look to regional and national government agencies who often do not have the resources to cope in such emergencies. this make people, such as those in Tacloban, dependent on forgien government help and on NGOs, such as charitable organisations
71
what were the physical impacts of typhoon Haiyan that affected vulnerability in Tacloban?
- Tacloban lies in the centre of the Philippines where tropical storms cross from the Pacific Ocean towards southeast Asia, which makes the region the most affected in the world by this type of hazard
- high rainfall of tropical cyclones which, on slopes where vegetation has been removed, will cause landslides that cause devastation to whole communities
72
what were the social impacts of Typhoon Haiyan?
- there were over 6000 fatalities, with over 1000 people declared missing
- bodies were discovered well into 2019 with some estimating the death toll to have rose to 10,000
-nearly 2 million people were made homeless and more than 6 million displaced, with at least 20,000 fleeing to the capital
- large areas cut off, with communication and power systems destroyed
- major roads were blocked and widespread looting was reported
73
what were the economic impacts of Typhoon Haiyan?
- an American army officer observed 'I do not believe there is a single structure that is not destroyed or severely damaged in some way'
- Tacloban city's airport was damaged by the storm surge
- the total damage has been estimated at $2.9 billion
74
what were the environmental impacts of Typhoon Haiyan?
- nearly 300mm of rainfall was recorded, much of which fell in under 12 hours
- huge storm surges, measuring up to 6 metres, which were responsible for most of the damage and loss of life
- the low-lying areas on the eastern side of Tacloban were particularly vulnerable with some areas completely washed away
- flooding, landslides and fallen trees made relief work almost impossible except from the air
75
what were the political impacts of Typhoon Haiyan?
- local government in many areas collapsed, so many local officials were killed during the storm
76
what were the responses to Typhoon Haiyan?
- over 1200 evacuation centres were set up
- 3 days after the storm, the main airport was reopened and emergency aid arrived
- power was restored in some regions after a week
- one million food packs and 250,000 litres of water was distributed within 2 weeks
- prompt action by WHO (world health organisation) ensured outbreaks of disease were kept isolated
- many countries contributed to the relief effort through cash donations or practical help
- the UK government deployed two navy ships to the Tacloban area supplying over 200,000 tonnes of aid, while the Americans sent numerous ships and aircrafts and over 13,000 service personnel
- long-term responses included rebuilding with stronger structures and replanting of damaged mangroves to dissipate the energy of tropical storm surges
77
how has the Philippines responded to reduce vulnerability?
- many of the local farmers have embraced bamboo as a crop, in addition to providing livelihood and a quick-growing building resource, it offers the additional benefit if contributing to flood control and soil stabilisation
- since 2013, the Philippines have implemented early warning systems e.g. PhiliAWARE- which used advanced modelling to provide the information to give early warning and aid rapid response
- since typhoon Haiyan there has been an increased focus on community-based disaster management
- typhoon Haiyan has driven the Philippines to become a regional and global leader in disaster risk education and in October 2024 the Philippines will host the Asia Pacific ministerial conference on disaster risk reduction, bringing together leaders from around the region to identify impactful and innovative solutions to disaster risk
78
what is a wildfire?
- wildfires are uncontrolled fires that can destroy forests, grassland and other areas of vegetation
- they usually occur in rural areas and are known as 'quasi-natural' hazards as they are caused both naturally and by humans
79
what 3 main things does a fire need to start?
1. oxygen which is provided by prevailing winds or when a fire draws in air from surrounding areas to create an in-rush of wind
2. fuel such as flammable material surrounding a fire e.g. trees, grass and even soil or buildings
3. combustible heat which can be provided by lightning, volcanic eruptions, burning campfires or deliberately started
80
what are the three types of wildfires?
ground fire- where the ground itself burns e.g. peat and tree roots, these fires are particularly difficult to extinguish ( can go for months )
surface fire- where the leaf litter and low-lying vegetation burns and they spread as a surface front, these fires are hotter than ground fires but easier to control
crown fire- where the fire moves rapidly through the canopy ( the top layer of vegetation ), there needs to be strong winds and steep slopes and fires are likely to be intense and fast-spreading due to the most fuel ( vegetation )
81
what is peat?
- an accumulation of partially decayed vegetation or organic matter that is high in carbon and has no oxygen due to water logged conditions
82
what is the ladder effect?
- this is fuel that can carry a fire burning in low-grounding vegetation to taller vegetation e.g. low lying shrubs / bushes that lie under the tree
83
what are the human causes of wildfires and give an example of each cause?
1) accidents- these can be as simple as cigarettes being thrown on the floor or campfires in forests that cause sparks
e.g. a camp fire in California began a wildfire on the 8th of November, causing 85 deaths and destroyed 18,804 structures
2) arson- starting fires deliberately which can spread widely e.g. California's park fire was caused deliberately by a man and is now the fifth largest wildfire in the states history
3) slash and burn- this is a farming method that involves the cutting and burning of plants in a forest to create land for things like cattle ranching or logging. slash and burn can produce heavy loads of burned material and that can fuel hotter, longer fires e.g. in Malaysia
84
what are the natural causes of wildfires?
1) vegetation type- thicker undergrowth or closely spaced trees allow fire to travel easier, as well as if there is more vegetation then there will be more fuel to ignite the fire
- also less moisture means drier conditions and easier ignition e.g. some trees such as eucalyptus and pine contain lots of oil and so burn very easily
2) climate change and weather conditions- rainfall must be sufficient for vegetation to grow, so there's plenty of fuel, areas experience distinct dry seasons when rainfall is low for a significant time and warm, dry weather causes water in the vegetation to dry up, so it's more flammable
- strong winds provide more oxygen to help the fire burn and
spread burning embers
3) El Nino- happens every 6-8 years and changes the weather conditions in certain countries e.g. Australia
4) lightning- the biggest natural cause of wildfires
85
what is El Nino?
- a naturally occurring ocean-atmosphere phenomenon that has major influence on weather and climate in Australia and the globe
- during El Nino there is warming of the sea surface temperature in the central and eastern pacific ocean and cooling to the north of Australia along with weakening of trade winds, this leads to a reduction in evaporation and rainfall leading to dry land and increased risk of fire
86
what is the Indian ocean Dipole?
- this is a climate phenomenon that occurs in the Indian Ocean
- it is characterised by irregular oscillations of sea surface temperatures, with the western Indian Ocean becoming alternately warmer ( positive phase ) and then colder ( negative phase ) than the eastern part of the ocean
- during a positive phase, warm water is pushed to the western part of the Indian ocean, while cold deep waters are brought up to the surface in the Eastern Indian Ocean
- westerly winds weaken allowing descending air and warm water to move drawing rainfall away from Australia
87
what are the primary social impacts of wildfires?
- people may be killed or injured if they don't evacuate in time
- homes are destroyed, so people may be left homeless
- wildfire can destroy power lines and damage reservoirs, leaving people without electricity or clean water
- wildfires can cause health problems e.g. inhaling smoke can cause long-term breathing difficulties
88
what are the secondary social impacts of wildfires?
- on going stress / depression due to the fire
- conflict can occur between neighbouring countries due to the fire or ash spreading
89
what are the primary environmental impacts of wildfires?
- faster surface run off in vegetation-depleted areas
- crops are destroyed
- soil is damaged as the fire removes organic matter
- smoke causes air pollution and water sources become contaminated with ash
90
what are the secondary environmental impacts of wildfires?
- localised climate change
- habitats destroyed which puts some animals at risk of becoming extinct
- atmospheric CO2 increase
91
what are the primary economic impacts of wildfires?
- loss of income earners
- crops destroyed which can leave subsistence farmers without a source of income
- cost of damage to businesses and homes
92
what are the secondary economic impacts of wildfires?
- tourism decreases as people may not be attracted to that specific area anymore
- implementations of new regulations as a result of the fire
- insurance costs rising
93
what are some political impacts of wildfires?
- reduced confidence in the government as a result of the fire
- conflict between neighbouring countries as a result of transnational fires and cross-border air pollution
94
what are some short-term responses to a wildfire?
- evacuation of communities
- providing water and powder
( flame retardant ) out of planes to put out large fires
- search and rescue and aid
- provide refuge for people e.g. evacuation shelters
95
what are long term responses of wildfires?
- rebuilding fallen infrastructure an re-strengthening
- putting vegetation further away from houses
- build buildings out of materials that are fire-resistant
- educating future generations to provide awareness and knowledge of what to do during a wildfire
- psychological support for people
96
why are wildfires important?
- some species need fire to survive e.g. lodgepole pines have a relationship with fire and the intense heat not only triggers seed release but also clears the forest floor, removing competing vegetation and creating space for the young pines to grow
- pine cones need fire as when they burn they open, releasing more seeds to drop on the floor, so when the other trees burn they can access more sunlight and new forests can grow
- smaller fires help to maintain large scale ones
- they help to maintain ecosystems by supporting the growth of native plants by clearing invasive species, restoring nutrients to the soil, killing pests that harm trees and they provide shelter and nutrients for animals
97
how do we prepare for a wildfire?
education- in areas affected by fires, governments often produce comprehensive guidance to help authorities and people prepare for fire hazards e.g. the department of homeland security recommends in California
community action- some programmes have been made that focuses on identifying the most vulnerable areas in fire-prone communities and then makes residents aware of how they can be responsible for their own safety, in which residents develop their own fire warning systems and survival strategies and techniques
computer modelling- this has been employed to understand and predict fire behaviour, it involves studying the ways in which fires behave to comprehend and predict it's behaviour
98
how do we mitigate against a wildfire?
- Colorado state university encourage the creation of 'fire-adapted communities' to increase forest resilience, they provide homeowners and communities with advice on how to reduce and even prevent damage to property by fire, such as through fire-resistant landscaping and planting fire protection measures within homes
- the public can take action e.g. preparing structures for fires and everyone sharing a responsibility
99
how do we adapt against a wildfire?
- individuals and authorities can change the way they live to help them cope with wildfires e.g. using non-flammable building materials and creating fire breaks ( gaps in trees ) around settlements to stop the fire from spreading
- for people who live in the forest you can:
- make your coniferous trees thin and prune and around 105-30 feet from your home to reduce the risk of larger trees creating a crown wildfire
- remove all but scattered trees within 30 feet of structures, this then reduces the amount of fuel that can start and spread the fire
- make sure the chimneys are clean so nothing flammable such as leaves don't come alight
100
how do we prevent against a wildfire?
education- wildfires, unlike other hazards are preventable to a certain extent, in regions prone to wildfires, education programmes, signs and posters are used to urge people to be:
- careful and advise them on how to avoid starting fires by:
- not leaving a fire or barbecue unattended and always extinghishing it fully with soil and water
- not discarding a lighted cigarette out of car windows
- removing litter, particularly any broke glass so sunlight does not reflect and start a fire
101
what is an example of a recent wildfire event?
- the Australian bushfire season 2019-2020 ( known as the Black Summer ), which began in June 2019 with several significant uncontrolled fires that continued throughout the summer, mainly the south-east of the country peaking during December and the end of January
- the nations capital, Canberra, was covered in a blanket of cloud which spread out across the Pacific Ocean
102
how did the Australian wildfire occur?
- it was an extremely dry and hot spring and early summer which provided optimal conditions for wildfires
- according to the Australian Bureau of Meteorology, it was the driest spring on record with record heatwaves with average temperatures of 40.9 degrees
103
what area in Australia gained global attention?
- Kangaroo Island in the state of South Australia located 112 km south-west of Adelaide, it is just 13.5km from the mainland as it's closest point
- over a third of the island is protected by nature reserves which are home to native wildlife
- more than half the island ( 215,000 ) was damaged
104
what were the major impacts of the Australian bushfire?
- more than 20% of Australia's forests burned during the devastating bushfires- an unprecedented proportion globally
- by the beginning of march 2020, an estimated 18.6 million hectares of forest and over 5,900 buildings ( including 2779 homes ) had been destroyed by the fires, with at least 34 people dead
- it is estimated that one billion animals were killed and some endangered species may have become extinct
- analysts projected the total costs of the fires to be US $70 billion
- the smoke from the fires travelled approximately 11,000 km across the south pacific ocean to Chile and Argentina
- NASA estimated that 306 million tonnes of CO2 had been emitted
- in the course of firefighting operations, an air tanker and two helicopters crashed resulting in the deaths of the 3 air tanker crews as well as 2 fire trucks involved in fatal incidents, caused directly by fire conditions, killing 3 fire fighters
105
what were the responses to the Australian wildfire?
- a number of states of emergency were declared across New South Wales, Victoria and the Australian Capital Territory
- reinforcement from all over Australia were called in to assist fighting the fires and relieve exhausted local fire crews
- the Australian defence force was mobilised to provide air support to the fire fighting effort and to provide man power and logistical support
- firefighters, supplies and equipment from Canada, New Zealand, Singapore and the US among others helped fight the fires, especially in new south Wales
