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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
        
        Descending air
        
        Clear, dry, stable
        
        Light winds
      - Low Pressure
        
        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
  - - - 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