Hostile Worlds: Living with Natural Hazards

*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

• 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

Continental

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

Oceanic

• 6-10 km
• 200 myo
• Higher Density
• Dark in colour - basalt

CONVECTION CELLS

• 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

PLATE BOUNDARIES

• 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 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

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

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

LEDCs:

• 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

MEDCs:

• 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

• 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

• 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

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!