The Restless Earth

The Restless Earth

1. Tectonic Plates

   • Centre of Earth; solid,iron & nickel called the core.
   • Around the core is the mantle - semi molten rock that moves slow.
   • Outer Layer = crust - thin about 20km (average)
   • Crust divided into slabs called Tectonic Plates.
   • Destructive Plate boundaries - Continental + Oceanic = Ocean Trench
     • Continental + continental = Fold Mountains
   • Constructive plate boundaires - Plates move away magma comes through to solidify, making new crust.
   • Conservative plate boundaries - Go past each other creating earthquakes due to the tension & pressure.

2. Fold Mountains

   • 2 continental plates push together, sedimentary rock which has built up between them. they are folded and pushed up.
   • Steep slopes & often very high.
   • Lakes between valleys & snow at peaks.
   • Humans use fold mountains for:
     • Farming
       • Crops & grazing animals
     • Mining
       • Metal ores
     • Tourism
       • Climbing & skiing.
     • Forestry
       • Make Paper.
     • Hydroelectric Power
       • Renewable energy source
       • Water source
   • CASE STUDY: The Andes
     • 7000km Long
     • 300km wide
     • Steep slopes & narrow valleys make access hard.
     • Relatively Poor soils.
     • Average height is 4000m
     • Farning
       • Terraces used to create flat land areas that retain water.
       • Llamas used for transport of milk,meat & wool.
     • Mining
     • Hydroelectric Power
     • Tourism
       • Inca Trail

3. Volcanoes (Destructive)

   • At destructive plate margin - oceanic plate down into mantel,melted & destroyed
     • This forms a pool of magma.
   • Magma rises through cracks in the rocks called vents.
   • magma erupts onto surface, where then it turns into lava forming a volcano.

4. Volcano (Constructive)

   • magma rises into the gap where plates have moved a part creating a volcano.

5. Volcano (Hot spots)

   • Volcano forms over parts of mantle that are really hot,
   • Hawaii was created by a Hot Spot.

6. Types of Volcano

   • Composite Volcanoes
     • Mount Fuji
     • Made up of ash and lava that erupted, then calls & hardens into layers
     • Creates a steep sided volcano.
   • Shield Volcanoes
     • Made up of lava only
     • low & flat, dome
     • Runny lava, flows quickly, spread wide.
     • Hawaiian Islands
   • Dome Volcano
     • lava only
     • Thick lava, slow moving, hardens quick
     • Dome at top
     • Mt. Pele - Caribbean

7. How we try to predict a volcanic eruptions

   • Lives at risk, damage caused minimised.
   • What scientists monitor:
     • Tiny earthquakes
     • Escaping gas
     • Shape of volcano, e.g. bulges in land, magma builtd up

8. Supervolcanoes

   • They occur at;
     • Hot Spots
     • Destructive Plate margins
   • E.G. yellowstone national park, USA
   • How are they created:
     • 1) Magma rises up through cracks
     • 2) Magma basin is formed
     • 3) Pressure causes circular bulge, could be several km wide.
     • 4) Bulge cracks creating vents.
     • 5) Lava comes through vents
     • 6) Lava erupts out of vents causing earthquakes
     • 7) Which sense up gigantic plumes of ask & rock
     • 8) Magma basin empties & collapses firing out more lava
     • 9) Eruption then finished leaving big crater called a Caldera
     • 10) Lake is formed in caldera, e.g. Lake Toba.
   • Characteristics
     • Flat & Dome.
     • Very big areas.
     • Have caldera (big crater)
   • Last super volcano is Lake Toba.

9. Earthquakes

   • Earthquake causes;
     • Destructive - plate gets caught when moving down into mantle.
     • Constructive - Tension builds along cracks within the plates.
     • Conservative - tension builds up when plates grinding peat each other get stuck
   • plates eventually jerk pst each other creating Shock waves (vibrations)
     • Shock waves spread out.
   • Epicentre - point on the earths surface straight above the area which the earthquake occurred.
   • How can they be measured:
     • Richter scale
       • It is showing energy released by an earthquake, called magnitude.
       • Measured magnitude of earthquake
       • Magnitude measured by seismometer.
       • Ranges from 1-9 - no upper limit
       • Major earthquakes above 5 on richter scale
     • Mercalli Scale
       • Measures effects
       • scale of 1-12
       • Observational scale (from peoples observation)
   • Where the earthquake actually happened
   • CASE STUDY: The Haiti earthquake
     • Happened January 12th 2010
     • Measured 7.0 on richter scale
     • 220,000 people or more died.
     • 1.5 million made homeless
     • 180,000 houses collapsed
     • Around $1 billion was pledged, including over £100 million by the UK
     • Tents provided for 1.9 million people.
     • The work bank cancelled Haiti's debt repayment for 5 years.
     • Happened on Conservative plate boundary.
   • CASE STUDY: Abruzzo Earthquake, Italy (2009)
     • April 6th 2009.
     • Measured 6.3 richter scale.
     • Collision plate boundary.
     • Just over 300 people died & 1500 people injured.
     • 5000-10,000 buildings were damaged but only a few collapsed.
     • Around 65,000 people made homeless.
     • A state funeral held 5 days after for the dead, now a national day of mourning.

10. CASE STUDY: Asian Tsunami

    • Boxing Day, 2004.
    • Earthquake that caused it was 9.1 on richter scale
    • Waves reached over 25m and travelled at over 800km/h in open water.
    • Occurred on a Destructive plate boundary.
    • 220,000+ died, including over 150,000 in Indonesia.
    • 650,000 were seriously injured.
    • 2 million were made Homeless.
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