The Restless Earth

The Restless Earth

1. Tectonic Plates

   • Earth's Structure
     • Crust
     • Mantle
     • Outer Core
     • Inner Core
   • Crusts
     • Continental
       • Thick
       • Less dense
     • Oceanic
       • Thin
       • More dense
   • Types of Plate Margins
     • Destructive
       • 2 plates move toward each other
       • Oceanic >< Continental means that oceanic is forced into mantle and estroyed
       • Continental >< Continental means that no crust is destroyed
     • Constructive
       • 2 plates move away from each other
       • Magma rises to fill gap, creating a new crust
     • Conservative
       • 2 plates move past each other
       • Crust isn't created nor destroyed

2. Fold Mountains

   • Formation
     • Thick sediment layers form in huge depressions called geosynclines under the sea
     • Over millions of years the sediments are compressed into rock
     • The sedimentary rocks are forced into folds as the plates move at destructive plate margins
   • Case Study - The Alps
     • Farming - high slopes for animals, low slopes for crops
     • Mining - major source of metal ores
     • Tourism - spectacular scenery, exciting activities
     • HEP - steep sided slopes ideal
     • Forestry - ideal environment to grow trees

3. Ocean Trenches

   • Formed in subduction zone of a destructive plate margin, by the subducting oceanic crust.

4. Volcanoes

   • Types
     • Composite
       • Made of ash and lava that's erupted, cooled and hardened to form layers
       • Lava is thick and flows slowly
       • Hardens quickly to form a steep sided volcano
     • Shield
       • Made of lava only
       • Lava is runny and flows quickly
       • Lava spreads over a wide area, forming a low, flat volcano
   • Case Study - Montserrat Eruption
     • Primary Impacts
       • Plymouth buried under 12m of mud and ash
       • Over 20 villages and 65% of homes destroyed by pyroclastic flows
       • Schools, hospitals, airport and port destroyed
       • Vegetation and farmland was destroyed
       • 19 people died and 7 were injured
     • Cause
       • Destructive plate margin
       • Magma rose through weak spots underground
       • Pool collapsed, vent opened and erupted
     • Secondary Impacts
       • Fires destroyed many buildings
       • Tourists stayed away, disrupting economy
       • Population declined from 20,000 to 12,000 since eruption
       • Volcanic ash has improved soil fertility
       • Tourism is increasing
     • Immediate Responses
       • People evacuated from south to north
       • Shelters built for evacuees
       • Temporary infrastructure built
       • UK provided £17 million of emergency aid
       • Local emergency services provided support
     • Long-term Responses
       • Risk map and exclusion zone created
       • UK provided £41 million to develop north of island
       • The Montserrat Volcano Observatory set up to try and predict future eruptions
   • Super
     • Formation
       • 1. Magma rises through cracks in crust forming a large magma basin, with the pressure forming a bulge
       • 2. The bulge eventually cracks, creating vents for lava to escape through. it then erupts causing earthquakes, spewing ash and rocks
       • 3. As the magma basin empties, the bulge collapses spewing more lava
       • 4. When the eruption is finished, a big crater, called a caldera, is left where the bulge collapsed
     • Flat
     • Cover a large area
     • Have a caldera
     • Global Consequences
       • Eruption will throw out thousands of cubic kilometres of rock, ash and lava
       • Thick cloud of super-heated gas will destroy everything in its path
       • Ash will block sunlight
       • Ash will settle burying fields and farms
   • Predicting volcanoes
     • Tiltmeters - measure bulges on volcanoes
     • Satellites - measure changes in heat activity

5. Earthquakes

   • Cause
     • Destructive margins - tension builds up when one plate gets stuck as it is moving down past the other into the mantle
     • Constructive margins - tension builds along cracks within the plates as they move away from each other
     • Conservative margins - tension builds up when plates that are grinding past each other get stuck
   • Location
     • Plate margins
   • Summary
     • The plates jerk past each other, and send out shock waves
     • The shock waves spread put from the focus, the point in the earth where the earthquake starts
     • The epicentre is the point on the earth's surface straight above the focus
   • Measuring Earthquakes
     • The Richter Scale
       • Measures amount of energy released by an earthquake, called the magnitude
       • It's measured using a seismometer, a machine that moves with the vibrations of the earth
       • It is logarithmic - an earthquake with a magnitude of 5 is 10 times more powerful than that with a magnitude of 4
     • The Mercalli Scale
       • Measures effects of an earthquake
       • Measures by asking eye witnesses for observations of what happened
       • Scale of 1 to 12, usually written in roman numerals
   • Case Study - L'Aquila, Italy
     • Info
       • 6th April 2009
       • 6.3 on Richter Scale
       • Caused by movement along crack in plate of destructive margin
     • Primary Effects
       • 250 deaths
       • Hundreds of people injured
       • Thousands of people made homeless
       • Thousands of buildings destroyed
     • Secondary Effects
       • Aftershocks hampered rescues and caused more damage
       • Fires in buildings caused damage
       • Broken water pipe caused landslide
     • Immediate Responses
       • Camps set up with necessities
       • Public services helped with rescues
       • International teams sent in as search parties
       • Money provided by government for rent
     • Long-term Responses
       • Italian PM promised to build a new town
       • Investigation looking into why modern buildings weren’t built to withstand earthquakes
   • Case Study - Kashmir, Pakistan
     • Info
       • 8th October 2005
       • 7.6 on the Richter Scale
       • Caused by movement along crack in plate of destructive margin
     • Primary Effects
       • 80,000 deaths
       • Hundreds of thousands people injured
       • 3 million people made homeless
       • Basic supplies cut off
     • Immediate Responses
       • People rescued by hand
       • Tents, blankets and medical supplies distributed
       • International aid brought in
     • Secondary Effects
       • Landslides buried buildings and people
       • Diarrhoea and other illnesses spread due to unclean water
       • Freezing winter conditions caused more casualties
     • Long-term Responses
       • 40,000 people relocated
       • Government money given to residents
       • Training provided to deal with such situations
       • New health centres set up

6. Tsunami Case Study - Indian Ocean

   • Causes
     • On 26th December 2004, there was an earthquake off the west coast of Sumatra, measuring 9.1
     • The plate moving down into the mantle cracked and moved very quickly, causing a lot of water to be displaced, triggering a tsunami with waves up to 30m high
   • Effects
     • 230,000 killed
     • Over 1.7 million people lost their homes
     • Infrastructure of many countries was damaged
     • 5-6 million people needed emergency food, water and medical supplies
     • Massive economic damage and tourism industry suffered
     • Massive environmental damage, mangroves, coral reefs, forests and sand dunes were destoryed
   • Short-term Responses
     • Hundreds of millions of pounds had been pledged by governments, charities, individuals and survivors in the next few days to pay for necessities
     • Foreign countries sent ships. planes and soldiers to rescue people
   • Long-term Responses
     • Billions of pounds pledged to re-build infrastructure
     • Programmes eet up to re-build houses
     • Tsunami warning system set up in Indian Ocean
     • Disaster management plans put into place in some countries