Hazards Flashcards
(140 cards)
1
Q
What is a hazard?
A
A hazard is a potential threat to human life and property caused by an event. Hazards can be human caused or occur naturally. An event will only become a hazard when it is a threat to people.
2
Q
What are the different types of hazard?
A
Geophysical - hazards caused by land processes, majorly tectonics (e.g. volcanoes)
Atmospheric - hazards caused by atmospheric processes and the conditions created because of these, such as weather systems (e.g. wildfires).
Hydrological - hazards caused by water bodies and movement (e.g. floods)
3
Q
What is risk?
A
Risk is the exposure of people to a hazardous event presenting a potential threat to them and their property.
4
Q
What is vulnerability?
A
Vulnerability is the potential for loss. Losses vary geographically, over time, and among different social groups.
5
Q
What is risk perception?
A
Risk perception is how we view a hazard. How we receive and process information relative to the hazard, which then determines our reactions if any.
6
Q
What determines hazard perception?
A
- wealth
- experience
- education
- religion and beliefs
- mobility
7
Q
What is the passive response to hazards?
A
Fatalism - the viewpoint that hazards are uncontrollable natural events, and any losses should be accepted as there is nothing that can be done to stop them.
8
Q
What are the active responses to hazards?
A
- Prediction - using scientific research and past events in order to know when a hazard will take place, so that warnings can be delivered and impacts of the hazard can be reduced. In some cases, hazards may also be prevented when predicted early enough (wildfires).
- Adaptation - attempting to live with hazards by adjusting lifestyle choices so that vulnerability to the hazard is lessened (earthquake proof buildings).
- Mitigation - strategies carried out to lessen the severity of a hazard (sandbags to offset flooding).
- Management - coordinated strategies to reduce hazards effects. This includes prediction, adaptation, and mitigation.
- Risk sharing - a form of community preparedness, whereby the community shares the risk posed by a natural hazard and invests collectively to mitigate the impacts of future hazards.
9
Q
How does incidence effect responses to hazards?
A
Incidence - frequency of a hazard. This is not affected by the strength of a hazard, it is just how often a hazard occurs.
Low incidence hazards may be harder to predict and have less management strategies put in place, meaning the hazard could be more catastrophic when it eventually does occur. Also, low incidence hazards are usually more intense than high incidence hazards. For example, there are only 36 recorded earthquakes since 1500 above magnitude 8.5, but millions of earthquakes that are too weak to be recorded every year.
10
Q
How does distribution affect responses to hazards?
A
Distribution - where hazards occur geographically.
Areas of high hazard distribution are likely to have a lot more management strategies, and those living in the area will be adapted to the hazardous landscape because it dominated the area more so than in places with low hazard distribution.
11
Q
How do magnitude and intensity affect responses to hazards?
A
Intensity - the power of a hazard (how strong it is and how damaging the effects are)
Magnitude - the size of the hazard, usually a measure of intensity.
High magnitude, high intensity hazards will have worse effects, meaning they will require more management.
Magnitude and intensity are not interchangeable terms. The magnitude is usually definable and can be a number - this does not change. Intensity is the effects on the person, and can change depending on the distance from the hazard or the management strategies combating high magnitude risks.
12
Q
How does level of development affect responses to hazards?
A
Level of development - economic development will affect how a place can respond to a hazard, so a hazard of the same magnitude may have very different effects in two places of contrasting level of development.
Even if the hazard is identical, an area with a lower level of development is less likely to have effective mitigation strategies as these are costly. Therefore, the effects of a hazardous event is likely to be much more catastrophic in a less economically developed area.
13
Q
What is the park model?
A
The park model is a graphical representation of human responses to hazards. The model shows the steps carried out in the recovery after a hazard, giving a rough indication of time frame. The steepness of the curve shows how quickly an area deteriorates and recovers. The depth of the curve shows the scale of the disaster.
14
Q
What are the stages of the park model?
A
Stage 1 - relief (hours-days)
- Immediate local response (medical aid, search and rescue)
- Immediate appeal for foreign aid (the beginnings of global response)
Stage 2 - rehabilitation (days-weeks)
- Services begin to be restored
- Temporary shelters and hospitals set up
- Food and water distributed
- Coordinated foreign aid (peacekeeping forces etc.)
Stage 3 - reconstruction (weeks-years)
- Restoring the area to the same or better quality of life
- Area back to normal (ecosystems restored, crops regrown)
- Infrastructure rebuilt
- Mitigation efforts for future events
15
Q
What is the hazard management cycle?
A
The hazard management cycle outlines the stages of responding to events, showing how the same stages take place after every hazard.
16
Q
What are the stages of the hazard management cycle?
A
Response - immediate action taken after event (evacuation, medical assistance, rescue)
Recovery - long term responses (restoring services, reconstruction)
Prevention - strategies to lessen effects of another hazard (barriers, warning signals developed, observatories)
Preparedness - being ready for an event to occur (public awareness, education, training)
17
Q
What is the structure of the earth?
A
Inner core
- Solid ball of iron/nickel
- Very hot due to pressure and radioactive decay (contains elements such as uranium that give off heat when they decay)
- This heat is responsible for the earth’s internal energy.
Outer core
- Semi-molten
- iron/nickel
Mantle
- Mainly solid rocks, and the rocks are high in silicon
- The very top layer of the mantle is semi-molten magma, which is known as the asthenosphere
Asthenosphere
- Semi-molten layer that constantly moves due to flows caused by convection currents.
- Movements are powered by heat from the core
Lithosphere
- Broken up into plates
- 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
Crust
- The thin top of the lithosphere
- Oceanic crust is dense and is destroyed by plate movement, continental crust is less dense and is not destroyed.
18
Q
What is plate tectonic theory?
A
The lithosphere is broken up into large slabs of rock called tectonic plates. These plates move due to the 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, then sinks. The edges of where plates meet are called plate boundaries.
19
Q
What happens at destructive plate boundaries for continental and oceanic plates?
A
- Denser oceanic plate subducts below the continental
- 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, known as composite volcanoes
20
Q
What happens at destructive plate boundaries for oceanic and oceanic plates?
A
- Heavier plate subducts leaving an ocean trench. Fold mountains will also occur
- Built up pressure causes underwater volcanoes to burst through the oceanic plate
- Lava cools and creates new land in the form of island arcs
21
Q
What happens at destructive plate boundaries for continental and continental plates?
A
As neither plate is very dense, pressure builds
Ancient oceanic crust is subducted slightly, but there is no subduction of continental crust
Pile up of continental crust on top of the lithosphere due to pressure between plates
Fold mountains formed from piles of continental crust
22
Q
What happens at constructive plate boundaries for oceanic and oceanic plates?
A
- Magma rises in between the gap left by the two plates separating, forming new land when it cools
- Less explosive underwater volcanoes formed as magma rises
- New land forming on the ocean floor by lava filling the gaps is known as sea floor spreading
23
Q
What happens at constructive plate boundaries for continental and continental plates?
A
- Any land in the middle of the separation is forced apart, forming a rift valley
- Volcanoes form where the magma rises
- Eventually the gap will most likely fill with water and completely separate from the main island
- The lifted areas of rocks are known as horsts whereas the valley itself is known as a graben.
24
Q
What happens at conservative plate boundaries?
A
Between any crust, the parallel moves in different directions or at different speeds. No plates are destroyed so no landforms are created. When these plates move, a lot of pressure is built up. On an 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.
25
What are young fold mountains?
Large mountain ranges where the layers of rock within them have been crumpled as they have been forced together. They can be formed at destructive or collisional plate boundaries, where tectonic plates are moving together forcing layers of rock to be crumpled upwards.
26
What are rift valleys?
Occur at constructive margins in continental areas. The heating and up-doming of the crust leads to fracturing and rifting. As the sides of the rift move apart, central sections drop down to form rift valleys. Active volcanoes are surface evidence of volcanic activity beneath the rift valley.
27
What are ocean ridges?
Long ridges of mountains created by 2 plates moving apart at a constructive plate margin. The rising convection currents in the asthenosphere push up the crust and cause rifting or cracking. This forces the two plates to diverge creating a central rift. New crust is created as the plates diverge because magma rises to the surface along this fissure from the asthenosphere. The lava which erupts is low viscosity basaltic lava so creates gentle sided shield volcanoes as it can flow a long way before it cools. Occasionally the submarine volcanoes may grow above sea level to form volcanic islands. Iceland is the largest example on the Mid-Atlantic Ridge.
28
What are deep sea trenches?
Deep water areas that run along a coastline which has a destructive plate margin. They are created by subduction, and mark the point where the Oceanic crust is being pushed under the Oceanic crust. There is often quite a large section of continental crust between this margin and the ocean's edge, and sometimes a volcanic island arc such as Japan or the Aleutian Islands can be found in between the trench and the continental shelf.
29
What are island arcs?
Where two oceanic plates converge the denser crust subducts the other. This creates a trench. As the oceanic plate descends it melts, and the magma rises forming a volcanic island chain, known as an island arc.
30
What is ridge push?
Ridge push - the slope created when plates move apart has gravity acting upon it as it is at a higher elevation. Gravity pushes the plates further away, widening the gap. As this movement is influenced by gravity, it is known as gravitational sliding.
31
What is slab pull?
Slab pull - when a plate subducts, the plate sinking into the mantle pulls the rest of the plate with it, causing further subduction.
32
What are hotspots?
Hotspots are areas of volcanic activity that are not 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 (Hawaii).
33
What is a volcanic hazard?
Volcanoes occur on plate boundaries where plates melt and magma erupts through a plate, or on a hotspot. A volcanic hazard is any volcanic activity or process that poses a threat to human life, livelihoods, and infrastructure. Most of these hazards are harmful and destructive to the surrounding area of a volcano, but some are long reaching and can affect distant places.
34
What hazards are associated with volcanoes?
- lava flows
- lahars
- glacial floods
- tephra
- acid rain
- pyroclastic flows (nuees ardentes)
35
What are lava flows?
lava can flow quickly or slowly depending on its viscosity. Silica makes lava viscous and slow, which is common in explosive eruptions.
36
What are lahars?
mudflows usually caused by melting ice at high latitudes.
36
What are lahars?
mudflows usually caused by melting ice at high latitudes.
37
What are glacial floods?
when temperatures are high from magma, glaciers or ice sheets at high temperatures quickly melt and a large amount of water is discharged.
38
What is tephra?
any type of rock that is ejected by a volcano
39
What are toxic gasses?
Released during some eruptions, gases like C02 can be toxic as they are heavier than oxygen so suffocate people
40
What is acid rain caused by a volcano?
caused when gases such as sulphur dioxide are released into the atmosphere.
41
What are pyroclastic flows?
clouds of burning hot ash and gas that collapses down a volcano at high speeds.
42
What is the spatial distribution of volcanoes?
Along constructive or destructive plate boundaries, or on hotspots. The ring of fire is an area of high volcanic activity and earthquake activity located in the pacific, and the majority of large volcanoes occur within this 25,000 mile belt.
43
How is the magnitude of eruptions measured?
Vulcanicity is measured using the Volcanic Explosivity index (VEI). The more powerful, the more explosive. The scale is logarithmic from VEI 2 onwards. Multiple features are considered when calculating the VEI, including how much tephra is erupted, how long it lasts, how high the tephra is ejected, etc. Intense high magnitude eruptions are explosive whereas calmer, lower magnitude eruptions are effusive.
44
How is the magnitude of eruptions measured?
Vulcanicity is measured using the Volcanic Explosivity index (VEI). The more powerful, the more explosive. The scale is logarithmic from VEI 2 onwards. Multiple features are considered when calculating the VEI, including how much tephra is erupted, how long it lasts, how high the tephra is ejected, etc. Intense high magnitude eruptions are explosive whereas calmer, lower magnitude eruptions are effusive.
45
How is the frequency of volcanoes classed?
Frequency of eruptions varies per volcano. Volcanoes are either classed as active, dormant, or extinct. 50-60 volcanoes erupt each month, meaning volcanic eruptions are always frequent. Usually, a higher frequency eruption means that the eruptions are effusive whereas low frequency means the eruptions are explosive.
46
How predictable are volcanoes?
Regularity of eruptions can help estimate when eruptions take place. Seismic activity, gases releasing, elevation etc. can all all indicate an imminent eruption, but there are no definite predictions to a volcanic eruption.
47
What are the primary impacts of volcanic eruptions?
Social
- People killed
- Homes destroyed from lava and pyroclastic flows
Economic
- Businesses and industries destroyed or disrupted
Environmental
- Ecosystems damaged through various volcanic hazards
- Wildlife killed
Political
- Government building and other important areas destroyed or disrupted
48
What are the secondary impacts of volcanoes?
Social
- Fires can start which puts lives at risk
- Mudflows or floods
- Trauma
- homelessness
Economic
- Jobs lost
- Profit from tourism industry
Environmental
- Water acidified by acid rain
- Volcanic gases contribute to greenhouse effect
Political
- Conflicts concerning government response, food shortages, insurance, etc.
49
How do people respond to hazards?
prevention, preparedness, mitigation, adaptation
50
How can volcanic hazards be prevented?
Volcanic eruptions cannot be prevented. Only the risk to people can be prevented by not allowing people near volcanic hazards.
51
How can volcanic hazards be prepared for?
Monitoring increases the notice of volcanic eruptions, meaning warnings can be given out.
Education on volcanoes in areas of risk so people know what to do if there is an eruption.
Evacuation procedures planned.
Training response teams.
52
How can volcanic hazards be mitigated against?
Direct intervention to the volcano (concrete blocks to steer lava away from at risk areas)
Strengthening buildings that are at risk of mudflows or ash pileup.
Evacuation and exclusion zones.
Mitigating effects on health by having emergency aid and rescue.
53
How can volcanic hazards be adapted to?
Move away from areas at risk.
Capitalise on opportunities, such as encouraging tourism.
Change profession so it is less likely to be affected by volcanic hazards.
54
When was the Nyiragongo 2021 eruption?
22 May 2021
55
What were the primary impacts of the 2021 eruption?
- At least 32 people died
- An estimated 450,000 were displaced or evacuated
- 17 nearby villages were badly affected by the fast flowing lava
- Hundreds of homes, a school and three health-care centres were destroyed
- A lot of the people who lived in the suburbs were farmers - they lost their homes and only source of income in one night
56
What were the secondary impacts of the 2021 eruption?
- Several earthquakes took place in the days after the eruption. The earthquakes destroyed buildings, and damaged underground water pipes and a reservoir
- Between 3,000 to 8,000 people crossed the border to find safety in Rwanda
- Around ten people died in a road traffic accident caused by the evacuation. Four prisoners died as they tried to escape their cells
57
What were the immediate responses to the 2021 eruption?
- The authorities built temporary shelters in six camps to house any displaced people. However, heavy rainfall in the region meant that many of the shelters were destroyed
- The government set up large camps several miles away from the city and worked with various national and international organisations to help mitigate the disaster
58
What were the long term responses to the 2021 eruption?
- UNHCR (the United Nations High Commissioner for Refugees) supported more than 1,300 families by funding accommodation in Goma
- Charities helped with the emergency response and also collected money to rebuild homes and provide support to people.
- A year on, most people are still living in makeshift shelters using sticks, stones, and any plastic sheets they can find
- Some families have been given small amounts of money to relocate but then left to their own devices
59
What is the difference between the focus and epicentre of an earthquake?
The focus is the point underground where the earthquake originates from. The epicentre is the area above ground that is directly above the focus.
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What causes earthquakes?
Plates do not perfectly fit into each other, meaning they do not move in fluid motions. At all boundaries, plates can become stuck due to the friction between the plates.
When the plates are stuck, the convection currents in the asthenosphere continue to push, which builds pressure. It builds so much that it cannot be sustained and the plates eventually give way. All of this pressure is released in a sudden movement, causing a jolting motion in the plates. This jolt is responsible for seismic movement spreading throughout the ground in the form of seismic waves.
61
What is the spatial distribution of earthquakes?
The ring of fire accounts for 90% of the world's earthquakes. The alpine-Himalayan belt accounts for 5% of the world's earthquakes.
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What scales is seismicity measured on?
Logarithmic richter scale and the Modified Mercalli Intensity Scale.
63
What is the Richter scale?
a measure of the strength of seismic waves.
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What is the modified Mercalli intensity scale?
a measure of the rate of the destruction caused. Unlike the Richter scale, the Mercalli scale has a definite end at 12. The Mercalli scale is subjected, meaning it can be disputed by humans.
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What is the magnitude of an earthquake dependant on?
the depth of focus. conservative boundaries have the shallowest focuses, meaning they are closer to the epicentre and the seismic waves are stronger. Destructive boundaries usually have deeper focuses, meaning that the seismic waves are spread over a larger are before they reach the epicentre.
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What is the frequency of earthquakes?
Earthquakes are frequent around the world and occur every day at boundaries. Hundreds of smaller magnitude earthquakes that cannot be felt by humans occur every day, whereas the stronger earthquakes are less frequent.
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What is the regularity of earthquakes?
Earthquakes follow no pattern and are random so there is irregularity between events.
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What is the predictability of earthquakes?
Earthquakes are almost impossible to predict. Microquakes may give some indication but the magnitude cannot be predicted as how strong they are is random.
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What hazards are caused by earthquakes?
shockwaves, tsunamis, liquefaction, earthquakes, landslides.
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What are shockwaves?
When two plates move side by side, friction builds up and pressure increases. This pressure is stored as potential energy, it cannot move so it just builds up. When the pressure becomes too much, the plates eventually move. All of the energy that has been built up must go somewhere, so it is 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.
71
What are tsunamis?
When an oceanic crust is jolted during an earthquake, all of the water above this plate is displaced. The water travels fast but with a low amplitude. As it gets closer to the coast, the sea level decreases so there is friction between the sea bed and the waves. This causes the waves to slow down and gain height, creating a wall of water that is on average 10 feet high, but can reach 100 feet.
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What is 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 large weight on it.
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What are earthquakes?
Ground shaking and displacement is the horizontal and vertical movement of the ground. The severity of ground movement depends on the magnitude of the earthquake, geology, and distance from the epicentre. Settlements that are close to the epicentre of a high magnitude earthquake where the geology is unconsolidated with a high water content will experience greater ground shaking. Buildings can better withstand the vertical movements associated with earthquakes than horizontal ones.
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What are landslides?
Earthquakes in mountainous regions often cause landslides and avalanches. Steep, unstable slopes are vulnerable to landslides. Their vulnerability is increased by deforestation and heavy monsoon rains so that even small earthquakes can cause landslides.
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What are the primary impacts of earthquakes?
- buildings collapse, killing and injuring people as well as trapping them
- businesses destroyed
- earthquakes can cause fault lines which destroy the environment
- liquefaction
- government buildings destroyed
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What are the secondary impacts of earthquakes?
- gas pipes rupture, starting fires which can kill people
- water supplies are contaminated as pipes burst, spreading disease and causing floods
- tsunamis lead to damage and flooding
- economic decline as businesses are destroyed
- high cost of rebuilding and insurance pay out
- sources of income lost
-radioactive materials and other dangerous substances leaked form power plants
- saltwater from tsunamis flood freshwater ecosystems
- soil salinisation
- political unrest from food or water shortages
- borrowing money for international aid
- can be initial chaos and lawlessness
77
What is prevention for an earthquake?
The majority of seismic hazards cannot be prevented. Earthquakes and tsunamis 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.
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What is preparedness for an earthquake?
Earthquake prone areas have extensive awareness strategies and education in place. Earthquake warning systems and tsunami warning systems after an earthquake. Evacuation plans and training.
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What is mitigation for an earthquake?
Search and rescue. Immediate emergency aid, evacuation. Demolishing older, unsafe buildings. Tsunami wave breaks and sea walls.
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What is adaption for an earthquake?
Move away from areas at risk. Capitalise on opportunities, such as encouraging tourism. Insurance if living in places of risk. Changing lifestyle choices. Building specifically designed earthquake proof buildings.
81
What was the Japan 2011 earthquake?
Japan experienced one of its largest seismic events on the 11th of March 2011. A magnitude 9.0 occurred 70 km off the coast of the northern island where the pacific and north american plates meet. It is the largest recorded earthquake to hit Japan and lasted 6 minutes. The earthquake triggered a tsunami which reached heights of 40 metres when it reached the coast. The tsunami wave moved 10 km inland in some places.
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What were the impacts of the Japan 2011 earthquake?
- 18,000 died, the majority of victims over the age of 60. 90% of the deaths were caused by drowning.
- 10% died as a result of being crushed by buildings or being burnt
- The disposal of bodies proved to be very challenging as crematoriums and morgues were destroyed. As a result, many bodies were buried in mass graves to reduce the risk of disease spreading.
- More than 300,000 had to live in temporary accommodation, as 300,000 buildings were destroyed and a further million were damaged.
- The estimated cost of the earthquake was £181 billion.
- Four ports were destroyed and 11 more were affected in the north east of Japan.
- 4.4 million households and businesses lost electricity
- 11 nuclear reactors were shut down when the earthquake occurred
- The Fukushima nuclear power plant was decommissioned because all six of its reactors were severely damaged. Seawater disabled the plants cooling system which caused the reactor cores to meltdown, leading to radioactive spillage.
- Agriculture was affected due to salt water contamination, meaning it was impossible to grow crops.
- The government debt was increased at a time where the government was attempting to reduce national debt
- There was a movement against nuclear power, which Japan was heavily reliant on, after there were several warnings years before the disaster about the poor defences that had been ignored.
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What were the responses to the Japan 2011 earthquake?
- Local facilities became refugee shelters and distribution centres for relief supplies.
- Worldwide fundraising for victims
- The UK sent 70 rescuers to Japan, including two search dogs, a medical support team, and 11 tonnes of specialised equipment.
- Japan had a history of blocking foreign aid, but this time the government requested foreign help.
84
What conditions are required for tropical storms to develop?
- Temperature - ocean temperatures must be around 26-27 C and at least 50 metres deep. Warm water provides the storm energy.
- Air pressure - must be in areas with unstable air pressure, usually where areas of high 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 early stages.
- Rotation - tropical storms only form around the equator, but no less than 5 degrees on either side. The coriolis effect is the effect of the earth's rotation on weather events. The storm spins because the earth is spinning, but there is no coriolis effect at the equator.
- 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 a trigger for the storm to develop, which will only further develop if other conditions are present.
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How do tropical storms form?
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. Overall, warm air is constantly rising and accumulating in the atmosphere.
2. When warm air rises, it cools, condensing into thunderstorm clouds.
3. The whole system is spinning due to the coriolis effect. In the southern hemisphere, the storm spins clockwise and it spins anticlockwise in the northern hemisphere.
4. The constant additions of energy from the warm air causes the storm to spin faster and generate higher wind speeds. At 39 mph the storm can be classed as a tropical storm.
5. The eye of the storm is in the centre. This is an area about 30 miles wide that is of extremely low pressure. Cool, dry air descends in the eye, causing the weather to be relatively 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. Warm, moist air rapidly rises here, with extremely high winds and torrential rain. When winds reach 74 mph, it becomes a hurricane/cyclone/typhoon.
7. When the tropical storm reaches a coast, the low pressure and high winds will cause a large amount of seawater to be taken into the system 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. Heavy rain can persist for days.
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What is the spatial distribution of tropical storms?
Most tropical storms occur between 5 and 20 degrees north and south of the equator. The highest number of storms occur in the north pacific affecting countries such as the Philippines and Japan.
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What scale is used to measure tropical storms?
Tropical storms are measured on the Saffir-Simpson scale based on wind speed and therefore power of the storm. It is measured with categories between 1 and 5.
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What is the frequency of tropical storms?
Tropical storms form in the northern hemisphere from June-November, and the southern hemisphere from November to April. The majority of tropical storms do not develop into strong storms and do not reach land. Tropical storms that are higher magnitude and reach land are thought to be increasing in frequency.
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What is the regularity of tropical storms?
Tropical storms are irregular because although they occur in the same areas, their path does not follow a set route - the route taken is dependent on the storm and the climatic conditions.
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What is the predictability of tropical storms?
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.
91
What hazards are caused by tropical storms?
High winds - Hurricane winds are strong enough to blow a house down, and also blow heavy debris at high speeds, which can cause damage and injure someone who comes into contact.
Flooding - coastal/river flooding from storm surges from heavy rain. River flooding also sends more floodwater to other places, which can cause areas outside of the tropical storm's path to flood.
Landslides - due to the soil becoming heavy when wet with high intensity rain.
Storm surges - large rise in sea levels caused by low pressure and high winds, pushing water towards the coast.
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What are the primary impacts of tropical storms?
- drowning
- debris carried by high winds can injure or kill
- buildings destroyed
- businesses destroyed
- agricultural land damaged
- beaches eroded
- sand displaced
- coastal habitats such as coral reefs destroyed
- government buildings destroyed
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What are the secondary impacts of tropical storms?
- homelessness
- polluted water supplies spread disease
- food shortages from damaged land
- rebuilding and insurance payout
- sources of income lost
- economic decline from sources of income destroyed
- river flooding/salt water contamination
- animals displaced from flooding
- water sources change course from blockages
- issues paying back international aid
- pressure for the government to do more about climate change.
94
How can you prevent tropical storms?
In current climates and weather conditions, tropical storms cannot be avoided. Strategies to mitigate climate change could prevent higher category storms.
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What is preparedness for tropical storms?
Awareness through education of what to do during a tropical storm. Evacuation plans and training. Satellite image tracking to manage areas that are at risk. Storm warning systems and television broadcasts tracking the storm.
96
What is mitigation for tropical storms?
Search and rescue, immediate emergency aid, evacuation. Strengthening the home though door barricades, roof strengthening, etc. clearing loose debris before storms.
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What is adaption to tropical storms?
Move away from areas at risk. Design buildings to withstand high winds and flood damage. Flood defences such as hoses on stilts, coastal walls, river levees, etc.
98
When and where was hurricane Maria?
Puerto Rico has a population of 3.3 million, and was struck by hurricane maria on the 20th of September 2017
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What are the impacts of hurricane maria?
- 64 died in storms
- Thousands more died from treatable illness because they could not access routine medical care
- Phones stopped working after the storm and batteries ran out without electricity
- Roofs were blown away, or were significantly twisted
- Wooden houses totally destroyed
- There was no running water and the electricity was gone for six months
- There was lots of rubbish across the streets, which attracted cockroaches and rats which spread disease. This resulted in a young child catching leptospirosis and dying
- Without electricity, people were unable to refrigerate anything, so they had to go to the shops everyday
- The price of doors had increased dramatically as everyone was buying them.
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What are the responses to hurricane maria?
- The community knew of the risk of flood, so they took what they could upstairs, and took measures to ensure the safety of the family
- Gringos from many different US churches arrived to help
- Aid trucks arrived to hand out food
- Old, sick people were reliant on their neighbours to collect food for them as aid wasn't delivered door to door
- Money from FEMA was going to help, but it only covered structural damage. People had lost beds, mattresses, and tables but got no support for that
- FEMA also couldn’t help if people couldn't prove that they owned the property, which many could not do
- Families received 1,500 USD in may from an organisation run by Jennifer Lopez.
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When and where was hurricane sandy?
Sand made landfall in New Jersey, during the evening of the 29th of October 2012 and was one of the most intense and damaging storms to ever affect the east coast of the USA.
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What were the impacts of hurricane sandy?
- At least 286 people were killed either directly or indirectly by Sandy
- 60 billion USD of damage caused
- Over 350,000 houses were damaged or destroyed in New Jersey.
- More than 18,000 flights cancelled
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What were the responses to hurricane sandy?
- The sick and infirm had already been evacuated, but everyone else waited at home
- People had insufficient time to protect or rescue their belongings
- Good forecasting and tracking of the storm from satellites, planes, and on ground sites
- Levees were overrun
- The Red Cross sheltered over 11,000 people
- Bridges and road tunnels closed
- The Red Cross was efficient at delivering food to stricken areas, but many enclaves were cut off and inaccessible
- 40,000 people had to be rehoused
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What is a wildfire?
A wildfire is a large, uncontrolled fire that quickly spreads through vegetation.
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How does vegetation type favour intense wildfires?
Thick, close together vegetation allows fires to spread quickly and easily. Trees and thick bushes lead to more intense wildfires, but grasslands do not burn as intensely. Vegetation with flammable oils (eucalyptus) causes more intense fires.
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How do fuel characteristics favour intense wildfires?
Vegetation should be dry to allow it to catch. Finer vegetation causes fire to spread quicker, but larger, thicker forms of vegetation burn for longer and more intensely.
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How does climate and recent weather favour intense wildfires?
Wildfires can occur anywhere in the world, but the most common areas are southern africa, western europe, and south america. Wildries occur in a climate that has enough rainfall to have sufficient plant growth, but considerable dry spells and droughts to dry out the fuel. Areas with dry seasons such as California allow for intense wildfires. Wind also causes wildfires to spread quicker. Many climatic events can make wildfires grow more intense and extend wildfire seasons. Recent temperature increases have caused an increase in the number of wildfires and an increase in the length of a wildfire season.
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What are the three main ways in which wildfires burn?
Crown fires burn the entire tree from bottom to top, which is classed as the most dangerous and destructive type of fire.
Surface fires only burn the leaf litter, meaning they are easy to extinguish
Ground fires burn at the dry peat or vegetation beneath the surface, and move slowly through the dried underground. Due to them being underground, they can be difficult to put out and can actually continue to burn throughout the year if the weather allows it.
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What causes wildfires?
Wildfires can be caused naturally or by humans. The majority of the time, wildfires are caused by human activity. Humans may start fires accidentally or through arson.
Natural causes include lightning, volcanoes, and spontaneous fires.
Human causes can be lit cigarettes, barbecues, agriculture, train lines, etc.
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What are the primary impacts of wildfires?
- People killed or injured in fires
- Homes destroyed
- People go missing during evacuations
- Businesses destroyed
- Agricultural land damaged
- Cost of fighting fires (firefighters, helicopters, water)
- Air pollution from ash
- Water pollution
- Habitats destroyed in fire
- Toxic gases released in burning
- Government buildings destroyed
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What are the secondary impacts of wildfires?
- Homelessness
- Food shortages from destroyed agricultural land
- Health problems such as asthma from smoke inhalation
- High cost of rebuilding and insurance payout
- Sources of income lost
- Discouraging visitors, losing tourism sector
- Planes cancelled
- Removing invasive species and stimulating seed germination
- Migration patterns of animals affected
- Increased CO2 from fires could heighten the greenhouse effect
- Borrowing money for international aid
- Pressure for the government to do more about global warming due to increased frequency
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How can you prevent and prepare for wildfires?
Public awareness can prevent the ignition of wildfires and prepare people for wildfires. In areas of risk, campaigns teach people the dangers of leaving fires burning in the forest areas through barbecues and cigarettes.
Warning systems are also a good way for people to be prepared. Broadcasted weather warnings warn people when the perfect conditions for wildfires are occurring. This means people may wish to evacuate and campfire bans can be put in place.
Thermal infrared satellite imagery shows where wildfires are occurring so that people can stay away from these areas. Therefore, evacuation zones can be set up for areas in high risk.
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How can you mitigate against wildfires?
Immediate responses to wildfires are mainly concerned with protecting those directly at risk and extinguishing the fire. Wildfires will need search and rescue teams, immediate aid, and evacuations. To immediately mitigate the effects, the fire must be extinguished or diverted. Firefighters are dispatched on ground to spray water onto the fire. Water and flame retardants are also sprayed onto large areas using aircraft.
Long-term mitigation strategies work to reduce the impacts of wildfires before they occur. Controlled burnings are created on purpose to remove flammable materials so that less fuel is available. These burnings are strictly monitored so that they are contained and easily extinguishable. Fire breaks (gaps in trees) are also created to limit the spread.
Those who live in areas at risk can also mitigate the effects of wildfires by ensuring their homes do not contribute to the spread of wildfires. This includes removing flammable materials from the vicinity so that in the event of a fire, your house is less likely to contribute to the spread.
To limit the effects of toxic gases and material that contaminates the ecosystem, homes can also be built using materials that will not produce harmful substances when burnt.
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How can you adapt to wildfires?
Many who live in fire-prone areas must adapt and live with the consequences of wildfires. The expenses of insurance and clean-up as well as staying educated become part of everyday life. We have to adapt our lifestyle in order to stop contributing so significantly to CO2 levels, heightening the greenhouse effect.
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Why is Victoria prone to wildfires?
The state of Victoria is located in the south-eastern corner of mainland Australia. Victoria is particularly susceptible to large, intense bushfires which can spread up to 30 km or more across landscapes. This is due to Victoria’s terrain, naturally flammable vegetation, and frequent exposure to hot, dry, windy weather.
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What is the context behind black Saturday?
The black saturday bushfires were a series of deadly bush fires that burned around February and March 2009. There were around 400 fires in Victoria, affecting 78 towns. Over 7000 people were displaced due to the fires. These bushfires resulted in the biggest loss of life from fires in history, with 173 dead and 414 injured.
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What processes caused black saturday?
Background temperatures reached 46 degrees, with winds reaching 100 km/h. This was precipitated by an intense heat wave and nearly 2 months of little or no rain. A weather front hit Victoria in the early evening of the 7th of February, which brought cooler temperatures and gale force winds. A change in the wind direction caused the fires' eastern flanks to turn into massive fire fronts, which burnt at high speed towards towns that were initially thought to be safe. Arson, machinery, lightning, and fallen power lines were confirmed to be causes of the fire. The average speed of the fire was 12 km/hour, but the heat of the fire was capable of killing people 400 metres away. Spot fires (fires ahead of the main fire caused by burning embers), were recorded 35 km ahead of the main fires.
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What were the impacts of black saturday?
173 died
414 injured
Over 2000 homes lost
Over 1 million animals died
Catchment areas that supplied Melbourne's top 5 dams were contaminated with ash and other substances
Agricultural losses
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What are the responses to black saturday?
Queen Elizabeth II made a donation to the Australian Red Cross Victorian Bushfire fund
A charity concert raised $8.8 million for the victims of the fires
Resulted in the creation of the bushfire prevention strategies
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When did Nyiragongo erupt in 2002?
On 17th of January 2002, Mt. Nyiragongo erupted. The volcano produced a fissure and three paths of lava, one of which headed toward the city of Goma, 18 km to the south.
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What risks were in Nyiragongo?
Lava lakes draining
Lake Kivu gas deposits could bubble up
Lava is fast moving due to steep sided volcano and low silica content
Subsidiary cone appearing in the city is a possibility
Earthquakes caused by the eruptions
Interaction of water and lava can become explosive (phreatomagmatic explosion)
There is not a chance of pyroclastic flow due to the non-explosive nature of the eruption
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What caused vulnerability in Nyiragongo?
Socioeconomic factors (poverty)
Conflict
Location (goma has a population of over 700,000 and is only 18 km south)
History of genocide, so people may be hesitant to evacuate to Rwanda
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How were hazards managed in Nyiragongo?
Monitoring of volcano increased after 2002, but was sometimes stolen/vandalised by the locals
By the 2021 eruptions, warnings were issued
Leaflets were spread containing shelters and evacuation routes
Advised not to rebuild on the lava flows
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What were the primary impacts of the 2002 Nyiragongo eruption?
More than 140 died, mostly from carbon dioxide suffocation
Hundreds of thousands lost their homes and fled to Rwanda
12,500 homes destroyed by lava flow and earthquakes triggered by volcanic activity
Lava completely covered 15% of Goma and destroyed around a third
Lava covered up to 80% of the airstrips at the Goma International Airport
Crops and livestocks were destroyed by the lava flows
Major disruption to mains water supplies caused by the eruption, leading to hygiene issues and drinking water shortages
400,000 people had to be evacuated from their homes to avoid the lava flows
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What were the secondary impacts of the 2002 Nyiragongo eruption?
2 of 4 of the cities hospitals collapsed due to subsequent earthquakes
Volcanic gases reacted with atmospheric gases and produced acid rain, which damaged farmland and cattle farms
Homelessness and overcrowding in refugee camps as many could not afford to rebuild their homes. Around 120,000 people were left homeless in Goma
Cholera spread in refugee camps due to both overcrowding and poor hygiene conditions due to disrupted water. Aid organisation were also worried about the spread of measles in the conditions
Lava flows destroyed businesses and shops, removing income sources and access to resources
Looting broke out in Goma after people evacuated and left the city relatively empty
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What were the immediate responses to the Nyiragongo 2002 eruption?
400,000 were evacuated from the area surrounding the volcano, but the evacuation was slow and only began once plumes of smoke leaving the volcano were visible. There were also limited evacuation plans in place
Many residents had not experienced a volcanic eruption before and were not aware that lava was dangerous. Many even went towards the volcano to look, which slowed the evacuation further
Due to the slow evacuation, around 50,000 inhabitants became stuck between two lava flows
The arrival of international aid was disrupted by the damaged airport in Goma
The United Nations had sent 260 tonnes of food to the affected area in a week.
UK oxfam sent 33 tonnes of water-cleansing equipment for 50,000 people in refugee camps. This stopped people from drinking from lake Kivu which helped to reduce the spread of cholera
The World Health Organisation conducted emergency measles vaccinations to 28,000 children to stop the spread
There was poor communication between agencies and refugees. With supplies low, many people began to travel back to the affected area within days to collect belongings from their homes, even though it was not safe to do so
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What were the long term responses to the Nyiragongo 2002 eruption?
Warnings about rebuilding Goma in the same location were ignored and the city has since quadrupled in size
Retraining of officials with precise evacuation plans
Training of community officers who can relay information to vulnerable communities if there is an eruption
30 new signs that detail early warning signs and evacuation routes have been put in high risk areas
Evacuation drills take place in communities and schools to prepare people for another eruption
Community-level distribution of leaflets to vulnerable people containing accessible information on eruptions. The leaflets include information on evacuation routes, local shelters, and general advice detailing what to do in an emergency
The Red Cross expressed need for more funding so that further educational materials can be released to communities in need
An observatory for the volcano was built
The large lava lake in Nyiragongo is visible from above, so the levels of it can be carefully monitored to see if an eruption is impending.
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What is the context behind the Philippines?
The Philippines is a group of 7,000 islands in the South China sea in southeast Asia. They are tropical islands, north of the equator. It has a vulnerable population of 98 million people who are at risk from a variety of hazards, including 11 million people in the densely populated coastal megacity of Manila.
The Philippines is a lower-middle income country, with a poverty rate of 21.6% and is developing fast. It has a rapidly increasing young population. The average population density is high, with 240 people per square km, with Manila having a density of up to 2,000 people per square km. Those who are very poor are living near the coast.
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What causes hazards in the Philippines?
Situated on a major plate boundary. The dense oceanic Philippines plate is being subducted beneath the Eurasian plate at a destructive plate boundary. This created the Philippine trench.
Its north and east coast faces the Pacific ocean
A tropical monsoon climate is experienced and it is subjected to heavy rain
Lies in Asia’s typhoon belt
Geophysical hazards: earthquakes, volcanic eruptions, tsunamis, landslides
Hydrometeorological hazards: typhoons, floods, droughts, landslides, wildfires
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What are volcanoes in the Philippines?
Contains over 37 volcanoes, 23 of which are active
Near to a destructive plate boundary whereby the dense oceanic crust of the Philippines plate is being subducted beneath the continental crust of the Eurasian plate
The islands were formed by a combination of folding at the boundary, and volcanoes formed from magma that has risen to the surface from the mantle below from the subducted Philippine plate
E.g. the eruption of Mount Pinatubo in June 1991, which killed 500 people and caused crop failure due to the falling ash. Global temperatures decreased by half a degree for 2 years.
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What are earthquakes in the Philippines?
Earthquakes can occur at fault lines in the area, where the plate has cracked under pressure
Between 1990 and 2012, earthquakes affected over 2 million people
E.g. 1990 earthquake on Luzon island was magnitude 7.8 and killed 1,500 people
E.g. 2006 earthquake killed 15 and damaged 800 buildings. It generated a local tsunami 3 m high and triggered landslides of materials from the parker volcano
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What are landslides in the Philippines?
Landslides can be triggered by volcanic activity in the area from earthquakes
Landslides can also be caused by heavy levels of rainfall which lead to cliff saturation if they fall in areas with a steep gradient
E.g. 2006 landslide at Guinsaugon on Leyte Island after 10 days of heavy rain, which buried a village and killed more than 1,300
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What are typhoons in the Philippines?
Vulnerable to typhoons developing in the west of the Pacific ocean
The philippines experiences between 7 and 10 typhoons annually
E.g. typhoon Haiyan in 2013, which had max wind speeds of 315 km/h before reaching land, the most powerful tropical cyclone to ever hit land, causing 6,500 fatalities
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What are tsunamis in the Philippines?
Submarine earthquakes in any of the surrounding plate boundaries of fault lines can cause a tsunami local enough to be devastating to the philippines
E.g. in 1976 a submarine earthquake of magnitude 7.9 caused a 45 m high tsunami which hit the coastline of the Moro gulf, damaging 14 buildings
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What are droughts in the Philippines?
Drought can occur when the wet season hasn't brought enough rain to last through the dry season, or when the dry season is particularly hard
E.g. Luzon island drought of 2005, whereby a reduction in rainfall decreased river discharge, which decreased economic activity in the area due to a lack of hydroelectric power
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What is flooding in the Philippines?
During the wet season, coastal floods can be caused by typhoon storm surges or rising ocean levels, an driver flooding can be caused by heavy rainfall, even in areas subject to drought
E.g. the December 2010 floods in Eastern Philippines following heavy rainfall, which resulted in displacing 450,000 people in 19 provinces, killing 25
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What are wildfires in the Philippines?
Forest wildfires in the Philippines are all human caused, and generally occur between January and June as this is the dry season.
There were 290 forest fires which occurred during 1995, the majority being of undetermined origin or unknown cause
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What makes the people in the Philippines vulnerable?
The population of the Philippines is largely vulnerable to the natural hazards, partially due to having a low capacity to cope.
Manila and the island of Luzon are densely populated, hence increasing disaster risk by increasing the impact of a hazard on people and their property when it hits those areas
Coastally distributed population, hence increasing vulnerability to hydrometeorological hazards
Landslide disaster risk has created as the pressures of an increasing population have led to deforestation of upland areas for agriculture, which reduces interception and water table capacity
Settlements have been built in vulnerable areas, for example a city was built near mount Pinatubo when it was classified as dormant. It then erupted in 1991
Widespread economic deprivation means the Philippines has a low capacity to cope, as they can’t afford to build stable hazard proof infrastructure, provide special educational programmes, or provide mitigation disaster kits.
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How are disasters managed in the Philippines?
National disaster coordinating council
Philippine Atmospheric, Geophysical and astronomical services
Philippine Institute of Volcanology and Seismology (PHIVOLCS)
Government legislation:
Land use planning e.g. preventing building in high-risk areas
Building regulations
Structural programme of defences e.g. building embankments to reduce flood risk in the case of tsunamis and tropical storms
70% of disaster spending must be used on long-term plans
Philippine National Red Cross (PNRC):
Started various programmes at community level e.g. train local volunteers in disaster management and cooperating with the government for financial support, ensuring programmes have sustainability and identifying risk through hazard mapping
Probably won't help people living in informal housing, but will improve new homes built that have proper planning permission.
