Hostile Worlds: Living with Natural Hazards

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  • Created by: Arjiv J
  • Created on: 23-04-16 11:42

Distribution of Volcanoes and Earthquakes / Struct

*see map of plate names/regions on Word Notes

Distribution of Volcanoes/Earthquakes

  • Linear patterns; lines of volcanic activity
  • Often coastal location
  • Except Himalayas
  • And Mid oceanic - Pacific/Atlantic

Structure of the Earth

  • Crust: solid outer layer - divided by tectonic plates
  • Mantle: Liquid layer on which the plates move
  • Core: Partially solid; made most of iron and nickel - same temperature as Sun
  • Continental Drift - idea that continents are slowly shifting their positions
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Plate Tectonics

  • Earth's surface made up of large number of large plates that are in slow,constant motion
  • @ the edges of these plates or PLATE BOUNDARIES, earthquakes and volcanoes occur
  • Convection currents in mantle move these plates


  • 35-70 km
  • 1500 myo
  • Lower Density
  • Light in Colour - granite


  • 6-10 km
  • 200 myo
  • Higher Density
  • Dark in colour - basalt
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Convection Cells/Plate Boundaries!


  • The Driving Force behind the plate movements is Convection Currents (Cells) in the Upper Mantle.
  • These are formed by the heat generated in the Radioactive Core.
  • This heats the magma in the mantle (heated magma is less dense than the magma around it)which rises and is replaced by cooler magma. 
  • These Convection Currents drag the plates which sit on top of them


  • Constructive or divergent plate margins occur where two plates are moving away from each other.  
  • Destructive or convergent plate margents occur where two plates are moving towards each other. 
  • Conservative or transform plate margins occur where two plates are sliding past each other


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Constructive Plate Boundaries!

Constructive or divergent plate margins occur where two plates are moving away from each other

  • Plates dragged apart allowing molten magma from the mantle to rise
  • Produces volcanic activity
  • Volcanic activity occurs beneath the oceans; basaltic lava erupts and mid-ocean ridges created
  • Volcanic Islands produced such as Iceland


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Conservative Plate Boundaries/Destructive Plate Bo

Conservative or transform plate margins occur where two plates are sliding past each other

  • Plates slide past each other 
  • No material created or destroyed
  • No volcanoes
  • Friction creates the earthquakes

Destructive or convergent plate margents occur where two plates are moving towards each other *see Words notes for diagram

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Impact of Earthquakes

Primary - Direct

  • Buildlings collapse
  • Landslides
  • Services; hospitals, power plants, phone towers collapse
  • Water/Gas pipes burst
  • Roads cracking - trains, ports, airports
  • LIQUEFACTION - weak ground very unstable - structures go through soil/ground when ground shakes

Secondary - Indirect

  • Panic/fear/confusion - pyschological impacts (after shock)
  • Death of people - Homeless
  • Cost of infrastructure damage - aid & economy
  • Lack of healthcare -> spread of disease
  • Civil unreset
  • Lack of communication
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Effects on LEDCs/MEDCs


  • Greater no. buildings collapse - earthquake protection materials not used
  • Less infrastructure - impact of destruction greater
  • Less able to repair
  • Not much insurance - lack of affordability/low value of buildings
  • High population density -> disease spreads easily
  • Lack of emergency services/hospitals


  • Appropriate technology/structure - more prepared for earthquakes -> less deaths
  • Well educated - prepared
  • Buildings insured/higher value - overall cost of damage greater
  • More infrastructure - more damage/higher costs -> less long term impacts - can afford higher costs
  • More hospitals/emergency services
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Living in an Earthquake Zone

  • Population Pressure - force exerted by growing population upon its environment, resulting in dispersal or reduction of the population
  • Fatalism - the acceptance of all things and events as inevitable
  • Adaptation - learning to or that you must live with the situation
  • Fear - too scared to live with it
  • Complacency - a feeling of quiet pleasure or security; unaware of some potential danger
  • Cultural Links - living there due to the culture, jobs and entertainment

Why live there?

  • Lifestyle: beach/coast -> moderate climate
  • Culture of the city: sports/heritage
  • Jobs/opportunities
  • Accessibility - trade/ports
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Managing the Hazard! Pt.1

  • USGS - United States Geological Survey - long term protection
  • CEA - California Earthquake Authority - on ground whilst earthquake occurs
  • FEMA - Federal Emergency Management Agency - responsible for clear up

1. Prediction

  • Seismographs monitor - small movements to indicate build up of stress
  • Hazard mapping - areas plotted according to degree of risk, allows more accurate planning of land use
  • Local signs can be monitored - changes in water levels in wells, abnormal animal behaviour and build up of radon gas
  • Prediction UNRELIABLE in short term

2. Building Controls

  • Minimum standard - for all new buildings - firm foundation/resistance to shaking
  • Flexible jointing - allows movement/ Rubber foundations built into central hollows
  • Shock absorption - steel/wood frames - Tower blocks with deep foundations
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Managing the Hazard! Pt.2

3. Land Use Zoning

  • Distance of known fault lines - disallow new buildings within a distance of a fault line
  • High-risk building - locate and take appropriate action
  • Avoid softer rock soils which are subject to liquefaction

4. Emergency Response

  • Japan undertakes earthquake drills for evacuation of cities threatened with earthquakes
  • Ensure emergency services are capable of quick response

*Thats it! See Word notes for extra resources/exams style questions. Make sure you do!

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