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1 Global Hazards - Coggle Diagram

- - - - Oceanic: 5–10 km, thinner, denser, younger
      - Continental: 25–90 km, thicker, lighter, older
      - Oceanic crust subducts beneath continental crust
  - - - Occur at all plate boundaries
      - ~90% around the Pacific Ring of Fire
    - - Mainly at constructive & destructive boundaries
      - ~75% around the Pacific Ring of Fire
      - Hotspots occur away from plate boundaries
    - - Constructive
        
        Plates move apart
        
        New crust formed
        
        Volcanoes & earthquakes
      - Destructive
        
        Plates move together
        
        Oceanic plate subducts
        
        Volcanoes & earthquakes
      - Collision
        
        Two continental plates collide
        
        Fold mountains form
        
        Earthquakes only
      - Conservative
        
        Plates slide past each other
        
        Friction builds then released
        
        Earthquakes only
  - - - Occur at all plate boundaries
      - Caused by pressure building as plates move
      - Focus: where earthquake starts
      - Epicentre: point directly above focus
    - - Moment Magnitude Scale: earthquake strength
      - Mercalli Scale: earthquake damage
    - - Shallow (<70 km): larger affected area
      - Deep (>70 km): more powerful, smaller affected area
      - Deep-focus earthquakes mainly at destructive boundaries
    - - Plates become locked
      - Pressure builds
      - Plates suddenly slip
      - Energy released as seismic waves
      - Can also be caused by mining & drilling
  - - - Steep-sided
      - Viscous (sticky) lava
      - Explosive eruptions
      - Destructive boundaries
    - - Gentle slopes
      - Runny lava
      - Frequent, less explosive eruptions
      - Constructive boundaries & hotspots
  - - - 25 April 2015, M7.8
      - Epicentre: Gorkha, 80 km NW of Kathmandu
      - Shallow focus: 15 km
      - 300+ aftershocks
    - - Collision boundary
      - Indian Plate collided with Eurasian Plate
    - - Social
        
        ~9,000 deaths
        
        20,000+ injured
        
        3.5 million homeless
        
        Schools & hospitals destroyed
        
        Water & electricity cut
      - Economic
        
        Businesses destroyed
        
        Tourism declined
        
        $7–10 billion damage (~35% GDP)
      - Environmental
        
        Landslides
        
        Avalanches (including Mount Everest)
      - Immediate Responses
        
        International aid (food, water, shelters, medical teams)
        
        Nepalese army deployed
        
        Tent cities established
        
        Search & rescue operations
        
        GIS used to coordinate relief
      - Long-term Responses
        
        Roads cleared & repaired
        
        Schools rebuilt
        
        Stricter building regulations
        
        Earthquake education & drills
        
        Government planning for future earthquakes
        
        International funding for reconstruction
- - - - Winds transfer heat Equator → Poles
      - Global circulation redistributes heat
      - Air moves in 3 atmospheric cells
        
        The 3-cell atmospheric wind model
        
        Transfer heat around Earth
        
        Create global pressure belts & climates
        
        Hadley Cell
        
        0–30°
        
        Warm air rises at Equator → heavy rain
        
        Air sinks at 30° → hot, dry deserts
        
        Trade winds blow towards Equator
        
        Ferrel Cell
        
        30–60°
        
        Air flows opposite to Hadley & Polar
        
        Rising air at 60° → unsettled weather (UK)
        
        Polar Cell
        
        60–90°
        
        Cold air sinks at poles → high pressure
        
        Air rises again near 60°
    - - Wind moves high → low pressure
      - Greater pressure difference = stronger winds
      - Warm air rises, cool air sinks (convection)
    - - Greatest at Equator, least at Poles
      - Caused by Earth's curvature & tilt
      - Unequal heating creates pressure belts
      - Short for incoming solar radiation
    - - Earth's rotation deflects winds
      - Northern Hemisphere → right
      - Southern Hemisphere → left
      - Low pressure: anticlockwise (N), clockwise (S)
    - - Trade winds: 30° → Equator
      - Westerlies: 30° → 60°
      - Polar easterlies: Poles → 60°
      - Formed by pressure belts + Coriolis effect
    - - Global circulation controls climate & weather
      - Lower pressure = stronger winds
      - UK: temperate, frequent Atlantic low-pressure systems
    - - High Pressure
        30N/30S
        
        Descending air
        
        Clear, dry, stable
        
        Light winds
      - Low Pressure
        60N/Equator/60S
        
        Rising air
        
        Cloudy, wet, unstable
        
        Strong winds
    - - Strongest between pressure belts
      - Greater pressure difference = stronger winds
    - - Warm, moist air rises → cools → condenses
      - Frequent in low pressure
      - Rare in high pressure
    - - Equator: hottest, wettest
      - 30°: hot days, cold nights
      - Poles: coldest (least insolation)
    - - UK
        
        Cooler, wetter
        
        Fewer extreme winds
        
        Temperate climate
      - Australia
        
        Hotter, drier
        
        More droughts & tropical cyclones
        
        Stronger extreme winds
    - - Climates Zones Around the World
        
        Temperate
        
        Low pressure belt (60N/S) caused by rising air from two cells meeting causing frequent rainfall.
        
        Moderate summers & winters
        
        Polar
        
        Temperatures are low all year round
        
        Tropical
        
        Temperatures are hot all the time and rainfall is high.
        
        Usually near the equator, where rising air from two cells meeting causes low pressure and lots of rainfall.
        
        Arid (Dry)
        
        Rainfall is very low all or most of the year.
        
        Temperatures are hot or warm
        
        Usually near 30*N/S, where sinking air from two cells meeting causes high pressure and prevents rainfall.
  - - - Form over warm tropical oceans (5–30° N/S)
      - Need 27°C+ water, 50–60 m deep, Coriolis effect
      - Called Hurricanes, Typhoons or Cyclones depending on location
      - 80+ storms/year; Pacific has the most
      - Intensity increasing; climate change may increase frequency, intensity & distribution
    - - Prolonged below-average rainfall
      - Caused by high pressure, failed monsoons, El Niño, atmospheric circulation
      - Common in Australia, Middle East, Africa, parts of N & S America
      - Climate change may increase frequency & severity
    - - Form in ITCZ where warm, moist air rises
      - Warm ocean (27°C+) creates intense low pressure
      - Trade winds + Coriolis effect make storm spin
      - Rising air cools → condensation & heavy rain
      - Lose strength over land or cool water
    - - Eye: calm, sinking air
      - Eyewall: strongest winds & heaviest rain
      - Outer bands: weaker winds & lighter rain
      - Rated using Saffir-Simpson Scale (1–5)
  - - - Trade winds weaken/reverse
      - Eastern Pacific becomes warmer than average
    - - Flooding: western South America
      - Drought: Australia & SE Asia
      - Happens every 2–7 years
      - Can reduce Atlantic tropical storms
  - - - Trade winds strengthen
      - Eastern Pacific becomes cooler than average
    - - Heavy rain: Australia & SE Asia
      - Drought: southern USA
      - More Atlantic tropical storms
      - Happens every 3–5 years
  - - - Background and causes
        
        Philippines lies in typhoon belt (western Pacific)
        
        30°C sea temperatures fuelled storm
        
        Open ocean allowed storm to strengthen
        
        Sea level rise, land subsidence & Tacloban's funnel-shaped bay increased storm surge
      - Typhoon Haiyan's Characteristics
        
        Category 5 at landfall
        
        195 mph (315 km/h) winds
        
        895 mb lowest pressure
        
        5–6 m storm surge
        
        400 mm rainfall
      - Impacts of Typhoon Haiyan
        
        Social
        
        6,201 deaths, 28,626 injured
        
        4 million displaced
        
        1.1 million homes damaged/destroyed
        
        16 million people affected
        
        Economic
        
        $13 billion damage
        
        Crops & farmland destroyed
        
        Infrastructure severely damaged
        
        State of national calamity declared
        
        Environmental
        
        Widespread flooding
        
        Forests & 33 million coconut trees destroyed
        
        Oil & sewage pollution
        
        Fishing communities badly affected
    - - Cause of 2018 Heat Wave
        
        Persistent high pressure (anticyclone)
        
        Hot air from continental Europe
        
        Atlantic depressions blocked
        
        Very low rainfall
      - Consequences
        
        Social
        
        Heat-related illness & 2,000+ deaths
        
        Drowning & thunderstorms
        
        Economic
        
        Rail tracks buckled & roads melted
        
        Water shortages affected farming
        
        Tourism & ice cream sales increased
        
        Environmental
        
        Wildfires
        
        Reservoir levels fell
        
        Crop & livestock losses
      - Responses
        
        NHS/government heat advice
        
        Hosepipe bans & water restrictions
        
        Farmers allowed extra water abstraction
        
        Rails painted white & services adjusted
        
        National Heatwave Plan introduced