Geography
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Hazards

Concept of a hazard

A ​hazard​ is a potential threat to ​human life​ ​and ​property​ caused by an event.
There are three major types of geographical hazard:
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human response to hazards

Perception 
People have different ​viewpoints of how ​dangerous hazards are and what​risk​they pose. These perceptions are dependent on ​lifestyle factors such as ​economic ​and ​cultural ​factors. For example, a person who is wealthy is perhaps less likely to view a hazard as dangerous as they may have the money to respond to it. 
 
Response 
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. 

Prediction: ​Using ​scientific research ​and ​past events in order to know when a hazard will take place, so that ​warnings ​may be ​delivered and ​impacts of the hazard can be ​reduced​. In some cases, hazards may also be ​prevented when predicted early enough. (e.g. predicting wildfires from climatic red flags)

Adaptation: Attempting to live with hazards by adjusting ​lifestyle choices so that vulnerability to the hazard is lessened. (e.g. earthquake proof houses.)

Mitigation: ​Strategies carried out to ​lessen the severity of a hazard ​(e.g. sandbags to offset impact of flooding)

Management: Coordinated strategies to reduce a hazard’s effects. This includes prediction,  adaptation, 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​. 

These responses are all affected by the ​aspects of hazards​. For example, ​higher magnitude hazards will clearly require more​management​.​Low incidence hazards will be harder to predict​, etc
 

park model

● Graphical representation​ ​of  ​steps carried out​ ​in hazard ​recovery
● Rough indication of ​time frame​. 
● Can be used in ​comparing hazardous events (e.g. a hazardous event that is in a low income country will have a longer recovery time). 
● The​ ​steepness​ of the curve shows how​ ​quickly​ ​an area ​deteriorates​ and ​recovers​. 
● The depth of the curve shows the scale of the ​disaster (i.e. lower the curve, lower the quality of life).

The Park Model of Human Response to Hazards

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hazard management cycle

The Hazard Management Cycle outlines the stages of responding to events, showing how the same stages take place after every hazard.
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plate tectonics

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Plate tectonic Theory

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​ ​(or plate margins).

 Different plate boundaries At plate boundaries, different plates can either move towards each other (​destructive plate margin), away from each other (​constructive plate margin), or ​parallel to each other (​conservative plate margin). Different landforms are created in these different interactions. This spider diagram outlines what landforms and processes occur at the boundaries: 
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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​ (such as Hawaii). 
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Hazards caused by volcanoes: 

● Lava flows
● Lahars (mudflows) - caused by a number of reasons, usually by melting ice at high latitudes 
● Floods - from melting ice sheets or glaciers at high latitudes
● Tephra​ - any type of rock that is ejected by a volcano
● Toxic gases - released during some eruptions
● Acid rain - caused when gases such as ​sulfur dioxide ​are released into the atmosphere
● Nuées ardentes​/pyroclastic flows - clouds of burning hot ash and gas that collapses down a volcano at ​high speeds
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Hazards can be responded to by ​preventing ​them directly, being ​prepared for the next hazard, mitigating the effects of the hazard, or completely ​adapting ​your lifestyle to limit the hazard’s effects. 
 
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Seismic Hazards
 ● Plates do not move in​ fluid​ motions
● At any boundaries, plates become stuck due to the ​friction between plates
● The pressure builds so much that it cannot be sustained and the plates eventually​ give way 
● The pressure is released quickly, causing a​ jolting motion​ in the plates
● This jolt is responsible for ​seismic ​movement spreading throughout the ground
● The​ ​focus​ is the point underground where the earthquake originates from
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Hazards caused by seismic events: 

● Shockwaves ​(seismic waves) - energy released from the sudden jolt that vibrates through the ground
● Tsunamis - caused when water is displaced from plates moving underwater, creating a large wave
● 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 
● Landslides and avalanches
 
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storm hazards

Tropical storm:​ a ​low pressure​, spinning storm with high winds and torrential rain. 

 Conditions​ for a storm to form: 
● Temperature: ​ Ocean temperatures must be around ​26 -  27°C ​to at least 50 metres deep.
● Rotation:​ Forms around the equator but no less than ​ ​5° on either side​.
​● Air pressure:​ Must be in areas of ​unstable air pressure​ ​- usually where areas of high pressure and low pressure meet (​convergence​) - so that warm air rises more readily and the clouds can form. 
 
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  • Home
  • Geography Trips
  • KEY STAGE 3
    • Yr 7 Knowledge Organisers
    • Yr 8 Knowledge Organisers
    • Why Should I Choose Geography?
    • Games and Quizzes
  • AQA GCSE
    • GCSE Knowledge Organisers
    • PAPER 1 PHYSICAL
    • PAPER 2 HUMAN
    • PAPER 3 APPLICATIONS >
      • Brindley Place
      • GEOGRAPHICAL SKILLS
  • AQA A LEVEL
    • Essay Planning
    • Exam Style Questions
    • Hazards Notes
    • Tectonic Hazard Case Studies >
      • Tohoku Case Study
      • Haiti Case Study
      • Eyjafjallajökull Case Study
      • Montserrat Case Study
    • Coasts
    • Changing Places >
      • Dharavi - Distant Place Study
    • Water and Carbon
    • Urban Environments
    • Global Governance