Natural Hazards Flashcards
Hazards
Hazard - A potential threat to human life and property caused by an event
How natural hazards are categorised:
- Geophysical - hazards caused by the movement of the earth e.g. earthquakes, volcanoes & landslides
- Atmospheric - weather related hazards e.g. tropical storms and droughts
- Hydrological - water related hazards e.g. floods and avalanches
Hazard perception
Hazard perception
- People have different perceptions of how dangerous hazards are and what risk they pose
- Wealth - The financial situation of a person will affect how they perceive hazards. Wealthier people may perceive a hazard to be smaller as they are less vulnerable e.g. can easily relocate. However, wealthier people may also view a risk as greater as there is more risk of property damage and financial loss than someone less wealthy (dependent on the person)
- Past experience - If people have experienced hazards before, it will influence their perception of future hazards e.g. if past experience was bad then perception of hazard is worse than if experience was relatively okay
- Education - People with more education may have a better understanding of hazards —> may feel more confident in mitigating the risks as they have more knowledge —> lead to a lower perception of risk. However, people who are less educated may not understand the full extent of a hazard and may not evacuate etc —> low perception of risk
- Religion - Some may view hazards as ‘Gods plan’ so may not perceive them to be negative
- Mobility - Those who have limited access to escape a hazard may perceive hazards to be greater threats than they are e.g. they may live in a secluded location (far from help or emergency services), or they may be have a disability or illness —> those who cannot easily leave an area quickly may feel more at risk
Human responses to hazards
Human responses to hazards:
- Humans can respond to hazards in a passive way (making no efforts to lessen a hazard) or in an active way
Fatalism (passive):
- The viewpoint that hazards are uncontrollable natural events - nothing that can be done to stop them
- Some communities say that it’s apart of ‘Gods plan’ —> they believe that it is meant to happen and that they shouldn’t do anything to stop it
Prediction (active):
- Using scientific research and past events in order to know when a hazard will take place —> allows warnings to be given in advance, helping to reduce the impact of the hazard
- Prediction is more likely in developed counties due to the availability of technology and qualified experts who can give more reliable forecasts
Adaptation (active):
- Attempting to live with hazards by adjusting lifestyle choices e.g. earthquake proof housing and practising earthquake drills
Mitigation (active):
- Things done to reduce impact of hazards e.g. sandbags to offset the impact of flooding
Integrated risk management (active):
- Analysing potential risks and implementing a coordinated approach to manage and reduce risks
- Typically better organised in developed countries due to greater resources
Risk sharing (active):
- Working together to reduce the risk and sharing the costs of hazard response e.g. buying home insurance —> only some people need to claim but the cost is shared by everyone
Factors affecting hazard response
Incidence:
- Incidence - how often a hazard occurs
- The more often a hazard occurs, the more likely that people will be prepared
Distribution:
- Distribution - where hazards occur geographically
- In more hazardous locations, people are more prepared for hazard events e.g. Japan has invested in earthquake-resistant buildings and earthquake drills
Intensity and magnitude:
- Intensity and magnitude - the size and strength of a hazard
- High magnitude, high intensity hazards will have worse effects
Level of development:
- Lower level of development - less likely to have effective mitigation strategies as these are costly - effects of a hazardous event is likely to be much more catastrophic
Hazard models
The Park Model (also known as the disaster response curve):
- Shows the effects of a hazard on quality of life over a period of time
- Pre-disaster
- Disruption - after the hazard occurs - the quality of life drops (duration of the drop depends on the severity of the hazard and the level of development of the country etc)
- Relief (hours to days) – the immediate responses e.g. search and rescue teams, emergency medical assistance etc
- Rehabilitation (days to weeks) - once the immediate impacts are under control, people start to resolve longer term problems e.g. temporary shelters are set up —> quality of life starts to improve
- Reconstruction (weeks to years) - this involves rebuilding permanent houses, infrastructure etc. This results in one of two outcomes —> If buildings etc are built to the same standard as before, the area returns to normal// If buildings etc are built to a higher standard than before, the area improves
Example:
- Initial impact of the hazard is greater in LICs due to lack of preparation
- Search and rescue teams takes longer due to lack of training and equipment/waiting for international aid
- Rehabilitation and reconstruction takes longer due to lack of money and corruption etc
- Life may still not have returned back to normal years later
Evaluation:
Positives:
- Helps us visualise the impact of the disaster
- Can compare it with other events to understand what factors worsen the impact of a hazard
- Shows the rate of recovery and shows if quality of life improves - helps us understand what techniques help to accelerate recovery
- Can indicate the magnitude or severity of the event - steeper dip - more severe
Negatives:
- Not good at showing quantitative data - does not show number of deaths, homes destroyed etc
- Does not show what was done before an event to help mitigate impacts - lack of mentioning of techniques prior to hazard means that the same techniques can not be used to help in other situations
- Doesn’t take into account secondary impacts
- Doesn’t take into account spatial variation e.g. some places will be worse affected than others (lower ninth ward and centre of new orleans)
The Hazard Management Cycle:
- Outlines the 4 stages of responding to events
- Preparedness - being ready for an event to occur e.g. warning systems in place, emergency kits or educating people about how to evacuate safely etc
- Response - immediate action taken after event e.g. search and rescue teams
- Recovery - this is about getting the affected area back to normal e.g. reconstruction
- Mitigation - strategies aimed to reduce the impacts of future disasters e.g. earthquake proof buildings
Evaluation:
Positives:
- Holistic approach - hazards are not only managed during the event but also in the periods before and after
- Includes mitigation and preparedness - reduces the risk before a disaster happens - (Evaluation: However, the effectiveness of this phase depends on the level of development of a country/government)
Negatives:
- Not good at showing quantitative data - does not show number of deaths, homes destroyed etc
- Doesn’t take into account secondary impacts
- Doesn’t take into account spatial variation e.g. some places will be worse let affected than others
- Climate change is making hazards more intense, making it harder to follow the HMC
- Assumes all phases are equally prioritised - in reality, governments may focus more on response and recovery rather than mitigation and preparedness, leading to repeated disasters
Typhoon Haiyan
- Date: November 2013 in the Philippines
- Category 5 storm - one of the most powerful storms ever recorded
Physical Vulnerability:
1. Low-Lying Land: Tacloban is at sea level, making it prone to flooding
2. Storm Surge + Rainfall: Surge of 6m, over 200mm of rainfall
3. High Winds: Winds up to 195mph
4. Warm ocean temperatures: Provided energy for the hurricane to strengthen (Pacific Ocean)
Human:
- Poor Infrastructure - Weak buildings// Roads and bridges were destroyed, delaying aid etc
- Cities like Tacloban are densely populated
- Wrong predicted path
Social:
- 6300 people died
- Over 4 million displaced
- 90% of Tacloban destroyed
Economic:
- 6 million people lost their source of income
- $20 billion financial cost
Environmental:
- 90% of Tacloban destroyed
Responses:
Responses before the typhoon:
- Path of typhoon was predicted and alerts were sent to areas which were expected to be hit the hardest (Evaluation: However, the actual path shifted slightly)
Responses during and after the typhoon:
Short term:
- 1200 evacuation shelters were set up (weaknesses: often overcrowded and under-equipped)
- The UK provided Shelter Boxes which provided equipment to set up temporary housing (weaknesses: these houses were often not durable or sustainable for long-term habitation - while they addressed short-term housing needs, they did not provide a permanent solution)
- The Philippines Red Cross delivered basic food packages (weaknesses: while basic food packages addressed urgent needs - not a long-term solution - can’t depend on external aid forever)
Long term:
- ‘Cash for Work’ programmes paid people to clean up debris (weaknesses: these programmes were temporary, meaning that once the cleanup was completed, many people were left without jobs)
- $4 billion allocated for rebuilding homes and infrastructure (weaknesses: funding shortages slowed reconstruction efforts - many remained in temporary shelters for years)
Structure of the earth
Earth’s structure:
- Crust
- Mantle
- Outer core
- Inner core
Crust:
2 types of crust:
- Continental - thicker (up to 70km thick) and less dense
- Oceanic - thinner (5-10km thick) and more dense
Mantle:
- Widest layer (2900km)
- Very top layer of the mantle is called the asthenosphere - semi molten
- Asthenosphere + crust = lithosphere
Core:
- Inner core - solid centre, lots of iron and nickel
- Outer core - semi-molten, mostly liquid iron and nickel
Plates:
- The lithosphere is divided into tectonic plates
- The places where plates meet are called plate boundaries or plate margins
- The core is the hottest part of the earth - this heat is the main driver of tectonic activity - heat is caused by radioactive decay of elements e.g. uranium and potassium inside the earth’s core
(Map of plates moving)
Plate tectonics
Plate tectonics:
Continental drift theory:
- Continental drift theory is the idea that continents were once joined together in a supercontinent called Pangaea - has since moved apart - it was proposed by Alfred Wegener in 1912
- Wegener’s theory was rejected as he couldn’t explain how continents moved - today the theory is widely accepted
Evidence for continental drift:
1. Jigsaw fit - continents (e.g. South America + Africa) fit together like puzzle pieces
2. Fossil evidence - identical fossils (e.g. mesosaurus) found on continents now far apart
3. Rock + mountain evidence - similar rock types and mountain ranges on different continents
Theories about how plates move:
- Until recently, scientists thought that convection currents were the main process causing plate movement
Convection currents:
1. The Earth’s core heats the lower mantle
2. Hot magma in the mantle becomes less dense and rises towards the lithosphere
3. Magma is cooler at the top as it is further away from the heat source - magma becomes more dense and sinks back down to the bottom
4. Cooler magma is reheated and begins to rise again - this continuous cycle moves tectonic plates
Slab pull:
1. At destructive plate margins, denser crust is forced under less dense crust
2. As the plate sinks, gravity pulls the plate down into the mantle
Ridge push (gravitational sliding):
1. As tectonic plates diverge (move apart), magma rises up to fill the gap created, then cools to form new crust
2. As the newly formed crust cools, it becomes denser and starts to slide away from the ridge due to gravity
Sea floor spreading:
1. As tectonic plates diverge (move apart), magma rises up to fill the gap created, then cools to form new crust
2. As the newly formed crust cools, it becomes denser and starts to slide away from the ridge due to gravity
3. When this happens at a plate margin under the sea, the sea floor gets wider - known as sea floor spreading
4. It creates structures called mid ocean ridges - ridges of higher terrain on either side of the margin
Evidence of sea floor spreading:
Plate margins - constructive, destructive, conservative
- Constructive (divergent) - plates move apart
- Destructive (convergent) - plates move together
- Conservative (transform) - plates sliding past each other
Constructive:
- Earthquakes and volcanoes occur at constructive margins
2 different landforms at constructive plate boundaries:
Ocean ridge:
- An ocean ridgeforms when the diverging plates are under the ocean
- As the plates move apart, magma rises up to fill the gap and this accumulates over time to become taller and wider
- The Mid Atlantic Ridge is an example of an ocean ridge
Rift valley:
- A rift valleyforms when the diverging plates are beneath the land
- As the plates move apart, the crust stretches and fractures
- Areas of crust drop down between faults to form a rift valley
- The East African Rift Valley is an example of a rift valley
Destructive:
- Earthquakes and volcanoes occur at destructive margins
Oceanic-continental:
- Where continental crust and oceanic crust converge, the more dense oceanic crust is subducted under the less dense continental crust. This forms a deep sea trench e.g. the Peru-Chile trench
- Fold mountains also form where the plates meet. They’re made up of sediments that have accumulated on the continental crust. The material pushed upwards as the oceanic crust is forced down e.g. The Andes
- The oceanic crust is heated by friction and melts into magma - the magma is less dense than the continental crust above and will rise back to the surface to form volcanoes
- As one plate moves under the other, this causes pressure to build up - causing an earthquake
Oceanic-oceanic:
- Most of the same processes occur where two plates of oceanic crust are moving towards each other the denser of the two will be subducted, forming a deep sea trench and triggering earthquakes and volcanoes
- An example of a deep-sea trench at an oceanic–oceanic boundary is the Mariana Trench
- Volcanic eruptions that take place underwater lead to crust building up - creates island arcs - clusters of islands that sit in a curved line e.g. the Mariana Islands
Continental-continental (collision boundary):
- Two plates of similar density move towards each other
- Neither is dense enough to subduct so the land is pushed upwards - this forms fold mountains e.g. the Himalayas
- Earthquakes are the main hazard at this type of plate boundary
- There is no volcanic activity here
Conservative:
- Earthquakes occur at constructive margins
- As the plates move past each other, pressure builds up - creating an earthquake
- San Andreas Fault
At constructive margins:
- Earthquakes - tend to be mild
- Volcanic eruptions - tend to be less explosive
- Mid Atlantic Ridge
At destructive margins:
- Earthquakes - tend to be strong
- Volcanic eruptions - tend to be explosive
At conservative margins:
- Earthquakes - tend to be strong
Volcanoes
Primary hazards:
Pyroclastic flows (nuée ardente)
- A pyroclastic flow is a mixture of super-heated gas and volcanic rock that flows down the sides of a volcano - travels at high speeds and flows a long way
- Because they travel fast and can happen with relatively little warning, pyroclastic flows can cause widespread death and destruction
- Mount Pinatubo in the Philippines
Lava flows:
- Lava flows travel at different speeds depending on slope, temperature and viscosity
- Most flows are relatively slow, so people have time to evacuate areas that will be affected
- However, lava flows destroy anything in their path, including buildings
- Mount Pinatubo in the Philippines
Volcanic gases:
- Lava contains gases such as carbon dioxide and sulfur dioxide, which are released into the atmosphere when a volcano erupts
- Some of these gases can be harmful to humans and animals if they’re breathed in e.g. sulfur dioxide can cause breathing difficulties
- Mount Pinatubo in the Philippines
Tephra and ash fallout:
- Tephra is material that has been ejected from a volcano during an eruption and falls back to the ground - When fallout consists mostly of ash, it’s called ash fallout
- 2010 Eyjafjallajökull eruption in Iceland produced an ash cloud that disrupted air travel in Europe for several weeks
Secondary hazards:
Mudflows (lahars)
- Mudflows occur when volcanic material mixes with large amounts of water (e.g. from rainfall or from ice melted by the eruption)
- Flows move very quickly and can travel very far - destroy everything in their path
- Mount Pinatubo in the Philippines
Acid rain:
- Volcanic gases can react with water vapour in the atmosphere, which then falls as acid rain - e.g. sulfur dioxide reacts with water to form weak sulfuric acid
- Mount Pinatubo in the Philippines
Distribution:
- Destructive margins, constructive margins and hotspots
- Many occur around the Ring of Fire
- Constructive Margins:
- Basaltic lava
- Very hot
- Low viscosity (runny)
- Not very violent
- More frequent
- Destructive Margins:
- Andesitic and rhyolitic lava
- Cooler
- More viscous (less runny)
- More violent - lava is viscous - forms blockages in volcanic vents - pressure builds up - violent eruption
- Less frequent
Magnitude:
- Can be measured using the Volcanic Explosivity Index - scale from 0 to 8 - based on the amount of material ejected and how high the material is blasted
Frequency:
- Usually, a higher frequency eruption means the eruptions are effusive whereas low frequency means the eruptions are explosive
Regularity:
- Some volcanos erupt at very regular intervals, whereas others may be dormant for hundreds or thousands of years
Predictability:
- Regularity of eruptions can help estimate when eruptions will take place
Signs of an eruption include:
- Ground deformation as rising magma causes bulges
- Increased gases
- Increased seismic activity
- It is important to be aware that while there are several methods used to predict volcanic eruptions, it is impossible to be certain about exactly when a volcano will erupt and with what magnitude - For example, Mount Ontake in Japan erupted suddenly and unexpectedly in 2014 killing 63 people. It hadn’t shown any signs of an eruption or increased activity so no warnings or alerts were issued
Earthquakes
- Earthquake - sudden, violent shaking of the ground
Earthquakes:
1. Tectonic plates move due to convection currents and processes like slab pull and ridge push
2. Plates get stuck and become locked together due to friction - causes pressure to build up
3. Eventually, the pressure is released - seismic waves travel outward from the focus
4. This causes intense ground shaking for seconds to minutes
5. The epicentre is the point on the Earth’s surface directly above the focus
Shockwaves:
- The movement felt during an earthquake is the result of seismic shockwaves
Primary - P waves:
- Fastest
- Travel through liquids and solids
- Least damaging
- Back and forth motion
Secondary - S waves:
- Slower than P waves
- Only travel through solids
- More damaging
- Up and down motion
Love - L waves:
- Slowest
- Travels through surface only
- Most damaging
- Side to side motion
Earthquakes can cause other hazards:
Tsunamis:
- Tsunamis are large waves caused by the displacement of large volumes of water
- The earthquakes cause the seabed to move, which displaces water. The greater the movement of the sea floor, the greater the volume of water displaced, and the bigger the wave produced
Landslides:
- Shaking of the ground can cause landslides - a landslide is the downward movement of soil and rock on a slope
- The risk of landslides is greater where soils are looser, slopes are steeper and where the shaking lasts longer or is particularly intense
Soil liquefaction:
- Occurs when the shaking causes loose or saturated soils to lose their strength. This causes them to act like a liquid rather than a solid and can result in significant damage to buildings and infrastructure
Measuring earthquakes:
Richter scale:
- The Richter scale measures the magnitude of an earthquake
- It doesn’t have an upper limit and it’s logarithmic
- An earthquake with magnitude 5 is ten times more powerful than an earthquake with magnitude 4
Moment magnitude scale:
- Moment magnitude scale (MMS) is based on the total amount of energy released by an earthquake
- It is logarithmic and has no upper limit
- It is more accurate than the Richter scale, so it’s more widely used
Mercalli scale:
- Mercalli scale measures the impacts of an earthquake using observations of the event (e.g. reports and photos)
- The scale is between I - XII (12 being the worst)
Distribution:
- Many occur around the ‘Ring of fire’
- Earthquakes occur on all plate margins - constructive, destructive, conservativeand collision
Magnitude:
- The biggest earthquakes occur at destructive plate margins, where one plate is forced beneath another. The subduction of a plate causes massive pressure to build up, causing a huge earthquake when it is released
- Earthquakes at constructive margins tend to be lower magnitude than at destructive or conservative margins
Frequency:
- Low magnitude earthquakes occur much more frequently than high magnitude earthquakes
- Around 55 earthquakes per day but most of these are low in magnitude and may not even be felt by humans
Regularity:
- Earthquakes don’t seem to follow any clear pattern or trend - their occurrence is largely random
Predictability:
- Scientists can identify which areas are most at risk from seismic hazards e.g. near plate boundaries - however, it’s currently impossible to tell when an earthquake will strike a particular place, and what magnitude it’s likely to be
- Unusual animal behaviour - in Japan, a large number of rats were seen everyday in a restaurant in Nagoya City which suddenly disappeared on the evening prior to the Nobi earthquake
- Temperature change - there seems to be some relation between temperatures and earthquakes - temperatures rose by 10-15 degrees before the earthquake in Lunglin, China
- Water level - changes in water level before earthquakes - rise in water level by 3cm before Lunglin
- Radon gas - 70% increase in radon concentration was reported 6 days before the Luhuo earthquake
Haiti earthquake
Haiti:
- Date: January 2010 at 4:53pm
- Magnitude 7 earthquake
Vulnerability:
Physical:
- 4:53pm - rush hour
- Haiti lies on the Caribbean and North American plate (conservative boundary)
- Epicentre was 16 miles of port au prince
- Shallow focus (5 miles deep)
Human:
- Haiti is one of the poorest countries within the western hemisphere
- Poor infrastructure - weak buildings
- Cities like port au prince are densely populated
Social:
- 230,000 people killed
- Displaced over 1 million people
- 8 hospitals in Port-au-prince were badly damaged
- 98% of the rubble on streets hadn’t been cleared, restricting aid access
Economic:
- 1 in 5 people lost their jobs
- $8 billion financial cost
Environmental:
- 98% of the rubble on streets hadn’t been cleared, restricting aid access
- The earthquake triggered landslides, restricting aid access
Responses:
Responses before the typhoon:
- There was no major earthquake preparedness plan despite Haiti being in a seismically active region
- Unlike countries like Japan, Haiti had no large-scale earthquake drills
- There were no enforced earthquake-resistant building codes, so most structures were poorly built and collapsed easily
Short term:
- Search and reduce teams sent from the USA and UK
- Over 1 million people placed in camps (weaknesses: while they addressed short-term housing needs, they did not provide a permanent solution//overcrowded and under equipped)
Long term:
- Reconstruction of homes, schools, hospitals etc (Evaluation: reconstruction was slow and hindered by corruption - many still lived in temporary shelters years later)
- $100bn aid from the US (Evaluation: However, only about 50% of the funds were used directly for earthquake-related needs)
Japan earthquake
Tropical storms
Storms
How are tropical storms measure?
1. Storms are classified using the Saffir-Simpson Scale, which is based on wind speed. Category 5 is the strongest (with winds over 250 km/h) and 1 is the weakest (with winds of 120-150 km/h)
3. Tropical storms are quite frequent - around one hundred occur each year. Some of these never reach land, so they never develop into a major hazard. Storms are more frequent in the northern hemisphere between June and November, and in the southern hemisphere between November and April
4. There are lots of factors that affect where and when a tropical storm will form, so they follow no clear spatial or temporal pattern
5. Certain cloud formations in tropical areas can be identified from satellite imagery and used to tell when a tropical storm is forming. The storm can then be tracked using satellite imagery and models, helping scientists to work out when and where it is likely to hit land. The path of a tropical storm can therefore be predicted
Storm hazards:
- High winds - winds can destroy buildings, uproot trees, and carry debris (e.g. cars and trees) long distances before smashing them into other objects
- Storm surges - a storm surge is a large rise in sea level. Strong winds pushes seawater onto land
- Heavy rain - as warm, moist air rises it cools and condenses, causing torrential rain
- Flooding - heavy downpours can cause river discharge to increase suddenly, causing rivers to overtop their banks and flood the surrounding area
- Landslides - water infiltrates soil and rock, making it less stable and increasing the risk of landslides
Social:
- People can be injured or killed by debris that’s blown around
- Houses are destroyed, so people are left homeless
- Electricity cables are damaged and supplies are cut off
- Flooding causes sewage overflows, contaminating water. The lack of clean water can help diseases spread
- Damage to agricultural land can cause food shortages
Political:
- 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
Economic:
- Buildings and infrastructure cost a huge amount to rebuild
- Businesses are damaged or destroyed
Environmental:
- Flooding
- Loss of vegetation
Responses:
- Short-term responses to a storm hazard normally occur immediately before, during or immediately after the hazard - they include things like evacuating people from areas at risk
- Long-term responses are often designed to mitigate the impacts of future storms by managing the risks. For example:
- Prevention - storms cannot be prevented, but they can be studied to help scientists understand which areas are most likely to be affected. This means that future developments can be planned to avoid high-risk areas
- Preparedness - people and authorities can make sure they are prepared for a storm, e.g. emergency services can train and prepare for disasters, governments can plan evacuation routes to get people away from storms quickly and educate people about how to prepare for a storm (e.g. stockpiling water and food and boarding up windows)
- Adaptation - buildings can be designed to withstand tropical storms e.g. by fixing roofs securely so they’re not blown off. Buildings can also be put on stilts so they’re safe from floodwater
Wildfires
- Wildfires - uncontrolled rural fire that destroys vegetation - if it reaches urban areas, it will destroy agricultural land and settlements
3 types of wildfire:
- Ground fire is where the ground itself (e.g. peat and tree roots) burns
- Surface fire is where leaf litter and low lying vegetation burns
- Crown fire is where fire moves rapidly through the canopy (the top layer of vegetation)
Benefits of wildfires:
- Small regular fires can reduce the amount of fuel build up - lower likelihood of large and more dangerous fires
- Fires remove alien plants that compete with native species for nutrients and space
- The ashes that remain after a fire add nutrients to the soil
Conditions that favour intense wildfires:
Vegetation type:
- Closely spaced trees allow fire to travel easily
- Some trees e.g. eucalyptus and pine, contain a lot of oil and so burn very easily
Fuel characteristics:
- Fine, dry material (e.g. long grass, thin twigs) burn very easily
Climate:
- Warm, dry weather causes vegetation to dry up - more fuel for fires
- Strong winds provide more oxygen to help the fire burn and spread
Fire behaviour:
- Fires can throw out burning debris that help the fire spread and become more intense
Natural causes:
- Lightning - biggest natural cause of wildfires
- Volcanic eruptions can produce very hot lava which can start fires
- El Niño - causes hotter weather in places like Australia - dries out vegetation - more fuel for fires// can lead to less rain - droughts - perfect condition for wildfires to start and spread
Human causes:
- Arson (intentionally starting a fire) - biggest human cause of wildfires
- Fires can be accidental e.g. by dropping cigarettes and allowing campfires/barbecues to get out of control
Effects of wildfires:
Social:
- People killed or injured
- Homes destroyed - homelessness
- Wildfires can cause health problems e.g. inhaling smoke can cause long-term breathing difficulties
Economic:
- Wildfires destroy businesses, leading to loss of jobs and income
- Insurance premiums increase dramatically after a wildfire
- The cost of fighting wildfires is huge
- Wildfires may discourage tourists from visiting an area, reducing income
Environmental:
- Habitats are destroyed
- Lots of CO2 released into the atmosphere
Political:
- Damage to agricultural land can cause food shortages, leading to conflict and political unrest
- Governments may have to spend money on repairing damage to buildings and roads, rather than e.g. hospitals and schools, so countries may not develop as rapidly
Long term responses:
Prevention/mitigation:
- Public education about the risks of using campfires and barbecues e.g. smokey bear campaign (reduced human caused wildfires by about 50%), cutting down trees around houses
Preparedness:
- Authorities can install wildfire warning systems - helps people evacuate e.g. text message alert
- Individuals can make sure they are prepared e.g. by finding out where their nearest emergency shelter is, or making an emergency kit
Adaptation:
- Adaptation is about how people change their behaviour to reduce risk or to cope with the impacts of wildfires
- For example, using non-flammable building materials
Examples of responses:
- Air drops - fire retardants are dropped from planes to try and put the flames out
- Firefighters spray the fire with water and foam
- Spray ahead of wildfires to prevent the fire spreading
- Fire lines - digging a trench in the vegetation - a break is made in the vegetation to try and prevent the wildfire from spreading
Positive feedback loops:
- Vegetation loss - decreased carbon sequestration - more CO2 released into the atmosphere - CO2 is a GHG - temperatures increase - wildfires
- Fires produce heat, causing hot air and smoke to rise - clouds form - thunderstorms can develop - thunderstorms produce lightning - wildfires
Australian wildfire case study (black summer)
- Date: The first fires in the Australia’s 2019-20 bushfire season were reported in September 2019, but peak activity occurred through December and into the New Year
- Location: The most severe fires were concentrated in NSW and Victoria
- Scale of Wildfire: The fires burned over 18 million hectares, making it the largest bushfire season in Australian history —> fatalistic response
Social:
- 34 people died (primary)
- Over 3000 homes were lost (primary)
- Air quality was severely hazardous to human health (secondary) (caused an extra 445 deaths)
Economic:
- Over $4.4 billion worth of property and infrastructure was destroyed (primary)
- Fire destroyed farmland —> job losses (primary)
- Recovery costs were over $10 billion e.g. rebuilding homes and restoring businesses (secondary)
- Reduction in tourism —> reduced tourism revenue by over $1 billion (secondary)
Environmental:
- Killed an estimated of 1 billion animals (primary)
- Burned over 18 million hectares of land (primary)
- Emitted of 300 million tonnes of CO2 (secondary)
- Caused extinction among some endangered animals (secondary)
Responses:
Short-Term Responses:
- The Australian Defence Force (ADF) assisted in evacuations and in delivering food, water, and supplies to affected areas (Evaluation: However, some areas suffered from resource shortages due to the scale of the disaster)
- Emergency shelters were set up to accommodate displaced residents (Evaluation: overcrowding)
Long-Term Responses:
- The Australian government allocated billions of dollars for the rebuilding of homes, businesses, and infrastructure (Evaluation: The rebuilding and recovery efforts were significant, but the scale of the destruction meant that many communities faced years of recovery)
- Calls for stronger action on climate change increased (Evaluation: While awareness increased, the Australian government has been criticized for not committing strongly enough to emissions reductions)
Vulnerability of the region:
Physical Vulnerability:
1. Hot and Dry Climate – Australia experiences extreme heat, with record-breaking temperatures exceeding 40°C (drought conditions)
2. Strong Winds – High winds spread fires rapidly
3. Flammable Vegetation – Eucalyptus forests contain oil that is highly flammable, fueling intense and fast-spreading fires
4. El Niño and Climate Change – Climate change has increased the frequency of extreme weather events, including prolonged droughts and higher temperatures, exacerbating fire risk
5. Difficult Terrain – Many bushfire-prone areas are mountainous, making firefighting and evacuation efforts challenging
Human Vulnerability:
1. Rural and Isolated Communities
- Many of the worst-affected areas were in rural Australia, where emergency services are limited, and access to roads, hospitals, and evacuation centers was difficult
- Elderly populations in these areas were particularly at risk, as they faced mobility issues and struggled to evacuate in time
2. Housing and Infrastructure Risks – Many homes were built in fire-prone bushland areas without sufficient fire-resistant designs, increasing damage levels
Iceland volcano
- Date: erupted in April 2010
Physical:
- Boundary: Constructive plate boundary between North American and Eurasian plate
- VEI 4 (Volcanic Explosivity Index)
- 150m thick ice cap melted which caused flooding
Impacts:
Social:
- No deaths and injuries
- 150m thick ice cap melted which caused flooding, leading to the evacuation of 800 people
Economic:
- The ash cloud and flooding damaged agricultural land - 20 farms were destroyed (Evaluation: Iceland has a resilient farming sector, so recovery was relatively quick)
- Over 100,000 flights were cancelled due to the ash in the air - over 10 million people were left stranded
- Airlines lost over £1 billion in revenue
- Tourism initially declined, but later increased as people visited Iceland to see the volcano - create opportunities in the long term
- Supply chain disruptions e.g. Kenyan flower exporters - highlights the interconnected nature of global trade - an event in Iceland can have repercussions thousands of miles away
- Some businesses saw an increase in revenue e.g. Eurostar saw a 30% increase in passengers (positive)
Environmental:
- 150m thick ice cap melted, which caused flooding
- 20 farms were destroyed by flooding and ash
- Decline in noise and air pollution due to less flights (positive)
- In the long term, nutrients released from ash improved soil quality (positive)
Responses:
Responses before the hazard:
- The initial eruption occurred a month before the big one, meaning emergency services were well prepared
- The close scientific observations in the area before the eruption made it possible to predict that an eruption would occur - necessary precautions were made such as warning people living nearby - Iceland had a good warning system with texts being sent to residents with a 30-minute warning
Short term:
- 800 local people evacuated due to flooding
- People in areas with heavy ash fall were told to stay indoors to avoid health risks
Long term:
- Close monitoring of Katla (a nearby volcano) increased - past eruptions of Eyjafjallajökull have been followed by Katla erupting
- Iceland marketed itself as a geotourism destination - demonstrates how countries can turn hazards into opportunities
Hurricane Katrina
- Location: South East USA
- Date: it formed over the Bahamas on the 23rd August 2015
Track of the Hurricane:
1. It formed over the Bahamas on the 23rd August 2015
2. It moved north west and strengthened as it passed over the warm water of the Gulf of Mexico
3. By the time it struck Louisiana and Mississippi on the 29th August, it was a Category 3 hurricane. It brought winds of around 200 km/h and 200mm rainfall to Louisiana, and a storm surge of up to 8.5m in Mississippi
Vulnerability:
Physical Vulnerability:
1. Low-Lying Land: New Orleans is below sea level, making it prone to flooding
2. Storm Surge & Rainfall: Surge of 6m, 380mm of rain, causing 80% of New Orleans to flood
3. High Winds: Winds of 175 mph caused significant destruction
Human Vulnerability:
1. Poor Infrastructure: The levees protecting New Orleans were built to withstand Category 3 hurricanes, leaving the city unprepared for Katrina’s intensity —> over 80% of the city flooded
2. Poor Government Preparedness: about 25% of residents didn’t own cars, leaving many unable to evacuate despite mandatory evacuation orders. This highlights the need for better evacuation planning for vulnerable populations without access to private transportation
Social:
* 1800 people were killed
* 300,000 houses were destroyed —> homelessness
* 3 million people were left without electricity
* One of the main routes out of New Orleans was closed because parts of the I-10 bridge collapsed
* Water supplies were polluted with sewage and chemicals. 5 people died from using contaminated water
* 18 schools in New Orleans were destroyed which disrupted education
Economic:
* 230,000 jobs were lost from damaged businesses
* 5300 km^2 of forest was destroyed in Mississippi, causing around $5 billion lost income from logging
* The total cost of damage was around $300 billion
* Famous New Orleans headquarter was damaged affecting tourism revenue
Environmental:
* Coastal habitats were damaged
* Some coastal conservation areas were destroyed e.g. Breton National Wildlife Refuge in Louisiana
* Flooding of salt marshes led to habitat loss
Responses:
Responses before the Hurricane:
- The USA has a sophisticated monitoring system to predict if and where a hurricane will hit. On August 26th the National Hurricane Center (NHC) in Florida issued a hurricane warning for Louisiana, Mississippi and Alabama —> this helped organisations to start preparing e.g.
* The US Coast Guard positioned helicopters and boats around the area likely to be affected
* Some areas e.g. New Orleans were told to evacuate. It’s estimated that around 80% of New Orleans’ residents were evacuated before the hurricane reached land (Evaluation: Although the warnings were accurate and timely, not all residents acted on them, partly due to socio-economic barriers —> In New Orleans, about 25% of residents didn’t own cars, leaving many unable to evacuate despite mandatory evacuation orders. This highlights the need for better evacuation planning for vulnerable populations without access to private transportation) (Human)
* Levees were built (Evaluation: The levees protecting New Orleans were built to withstand Category 3 hurricanes, leaving the city unprepared for Katrina’s intensity —> over 80% of the city flooded) (Human)
Responses during and after the hurricane:
* Emergency shelters were set up for people who hadn’t evacuated e.g. the Louisiana Superdome in New Orleans sheltered 26,000 people during the hurricane (Evaluation: food supplies ran out at the Superdome, it became overcrowded and conditions became unsanitary. The overcrowding showed that there was a lack of adequate planning) (Human)
* The police, fire service and army rescued over 50,000 people after the hurricane hit
* Organisations sent search and rescue teams, medical teams and supplies into the area after the hurricane
* Charities collected over $4 billion of donations from the public to provide aid (e.g. food) to victims (Evaluation: Lack of coordination between organisations sometimes delayed the delivery of aid)
How have the impacts changed the character of New Orleans?
- Many people evacuated and never returned - fewer than 200,000 people returned - black americans left
- Efforts to rebuild and improve the city led to an influx of wealthier, often younger, residents, changing the economic and social makeup of neighborhoods. Rising property values and rents have led to gentrification, displacing long-time residents
- Newer housing developments, often built to more rigorous safety standards, have changed the architectural feel in some areas
Magma plume
Magma plumes:
- Most volcanic activity occurs at plate margins, but there are some areas of intense volcanic activity that aren’t near any plate margins - these are caused by magma plumes
- A magma plume is a vertical column of hot magma that rises up from the mantle (the ground above the magmas plume is called a hotspot)
- Volcanoes form above magma plumes
- The magma plume remains stationary over time, but the crust moves above it
- New volcanoes form in the part of the crust that is now above the magma plume
- As the crust continues to move, a chain of volcanoes is formed
- The chain of islands that makes up Hawaii was formed by a magma plume
Volcanic event impacts and responses
Social:
- People are killed, and buildings and infrastructure are destroyed by pyroclastic flows and fallout
- Mudflows can cause further damage and deaths
Environmental:
- Ecosystems can be damaged or destroyed by pyroclastic flows and fallout
- Acid rain can cause acidification of aquatic ecosystems, killing animals
- Volcanic gases contribute to the enhanced greenhouse effect and can add to global warming
Economic:
- Pyroclastic flows and fallout can destroy businesses
- Ash clouds can prevent aircraft flying
- Damage to buildings and infrastructure can be very expensive to repair
- Eruptions and the scenery they form can attract tourists, boosting the economy
Political:
- Damage to agricultural land can cause food shortages, leading to conflict and political unrest
- Governments may have to spend money on repairing damage to buildings and roads, rather than e.g. hospitals and schools, so countries may not develop as rapidly
Long term responses:
Prevention/mitigation:
- It’s not possible to prevent a volcanic eruption
- However, it is sometimes possible to prevent eruptions posing a risk to people e.g. authorities can prevent the land around volcanoes from being developed// building codes to increase the resilience of buildings to volcanic hazards// education and training to improve response
Preparedness:
- Authorities can install monitoring systems to predict when an eruption might occur - helps them evacuate people e.g. iceland text message system
- Individuals can make sure they are prepared e.g. by finding out where their nearest emergency shelter is, or making an emergency kit
Adaptation:
- Adaptation is about how people change their behaviour to reduce risk or to cope with the impacts of eruptions e.g. tourism can provide an alternative income if people lose their livelihoods following an eruption
Earthquakes
Factors impacting severity of earthquakes:
- Plate boundary e.g. destructive - causes more destruction
- Depth of focus - deep focus earthquakes generally do less damage than shallow focus earthquakes - shock waves have to travel further to reach the surface, which reduces their power
- The severity of the hazard also depends on where the event occurs e.g. a mid-ocean earthquake may have fewer impacts than one on land
Earthquake impacts:
Social:
- Death and injuries
- Damage to infrastructure
- Liquefaction, mudslides, tsunamis - kill more people and damage more infrastructure
Environmental:
- Ecosystems can be damaged via landslides, liquefaction and tsunamis
- Power plants can be damaged, causing leaks of chemicals or radioactive material e.g. 2011 earthquake and tsunami in Japan caused the release of radioactive material from the Fukushima nuclear power plant
Economic:
- Earthquakes can destroy businesses via liquefaction, tsunamis and landslides
- Damage to buildings and infrastructure can be very expensive to repair
Political:
- Damage to agricultural land can cause food shortages, leading to conflict and political unrest
- Governments may have to spend money on repairing damage to buildings and roads, rather than e.g. hospitals and schools, so countries may not develop as rapidly
Long term responses:
Prevention/mitigation:
- It’s not possible to prevent seismic hazards
- However, it’s sometimes possible to prevent them posing a risk to people e.g. authorities can prevent land that is prone to liquefaction from being built on, or build giant sea walls to prevent tsunamis hitting land
Preparedness:
- Authorities can install earthquake warning systems - helps people evacuate e.g. text message alert
- Individuals can have plans for how people should respond during an earthquake e.g. staying away from buildings if possible, finding a desk to shelter under if inside
- Children have earthquake drills at school e.g. in China and Japan
Adaptation:
- Adaptation is how people change their behaviour to reduce risk or to cope with impacts
- Buildings can be designed to withstand earthquakes e.g. large rubber shock absorbers in the foundations, cross bracing on the structure and open areas where people can assemble if evacuated
