Tectonic Landscape

Tectonic Landscape

1. Earthquakes and Volcanoes

   • Normally found in narrow bands such as: in the middle of the oceans-e.g: Atlantic also known as a hot spot or along the edges of continent-e.g: West coast of America
   • Hot spots is when tectonic activity occurs in the middle of tectonic plates where the crust is thin and hot magma can escape.
     • If it happens under seas, the lava builds up to form island such as: Hawaii and Lanzarote

2. Tectonic Plates

   • How do they move?
     • They move as a result of convection currents in the earth's mantle. The movement,direction and type of crust will determine-show what tectonic activity will occur.
   • 3 types of plate Boundaries
     • Convergent/Destructive
       • They collide
         • Very violent volcanoes and earthquakes occur
           • Mt St Helens (USA)
           • Mountain Edna (Sicily)
         • The oceanic crust subducts (goes down and melts) into the mantle beneath the less dense (can float) continental crust.
         • Fold Mountain
           • Plates move together and collide again-allowing sedimentary rock on the sea floor to become crumpled and folded
           • Where an area of the sea separates two plates, sediment-sand, rocks and stuff- settles onto the sea floor called geosyncline, which then becomes compressed into sedimentary rock.
           • Eventually folded sedimentary rock shows above sea level as a range of folded mountains.
           • E.g Alps and the himalayas
     • Divergent
       • Plates move apart
         • Less Violent Volcanoes and Earthquakes occur
         • New sea floor is created at mid-ocean ridges as magma rises up through the ridges and solidifies
           • E.g: Mid-Atlantic Ridges
     • Conservative
       • Plates slide pass each other.
       • No crust is destroyed or created, therefore no volcanoes are formed
       • Plates can 'stick', this increases pressure which can be released as violent earthquake.
       • E.G: San Andreas Fault California USA
   • 2 types of Crust
     • Oceanic Crust
       • Consists of younger rocks
       • Heavier or denser (can sink)
       • Thinner:<10Km thick
     • Continental Crust
       • Older rocks
       • Lighter or less dense (can float)
       • Thicker:25-70km thick

3. MeasurigEarthquakes

   • The Richter Scale
     • measures the energy released during an earthquake
     • As the magnitude increases, as you move up the scale-logarithmic scale (like a line graph scale)
     • No upper limit of the scale
     • Sensitive scientific instrument called a Seisometer is used.
   • The Mercalli scale
     • It measures the effects or impacts of the earthquake, the damage done and what people feel (the amount of movement)
     • Scale measured in roman numbers from I-IIX meaning 1-12
   • Energy produced by earthquakes is at its greatest two points
     • Epicentre
       • The point on the surface directly above the focus-the place where the greatest effects will be felt
     • Focus Point
       • Focus point-the central point of the earthquake deep under the surface, where the earthquake actually happens.

4. Living with Hazards-why do people live in areas like these?

   • Social reasons
     • Some people worship Volcanoes, believing they are ancient spirits.
       • Example: Mountain Merapi Indonesia (MIC) and Mountain Fuji, Japan (HIC)
     • Earthquake-proofed buildings and disaster plans make people feel safer.
       • Example: San Francisco, Calfornia, USA (HIC), Japan (HIC), Haiti (LIC)
   • Environmental Reasons
     • Volcanic Area may attract tourists, bringing jobs and higher income
       • Example: Mountain Etna, Sicily (HIC), Mountain Laki or Heimaey, Iceland (HIC)
     • Earthquake areas are often of great natural beauty, where people like to live.
       • Example: San Francisco, California USA (HIC)
   • Economical reasons
     • Soils are often very fertile due to the ash, with lots of farming opportunities
       • E.G: The volcanic soils of Colombia are used for coffee crops-MIC
     • Mineral such as: Diamond, gold and tin are found in volcanic soils
       • E.G: Copper, gold and silver mining on St Helens, USA (HIC)
     • Some areas offer employment opportunities, with high-income jobs
       • Example: Silicon Valley in California (HIC)
       • Japan-HIC
     • Popular tourist areas and desirable locations with jobs and income opportunities
       • Los Angeles-California (HIC)

5. Preventing tectonic Hazards

   • Planning and prevention
     • Volcanic eruptions
       • Barriers or ditches
         • Made from concrete or rock are used to divert lava flow away from settlements (e.g: Mountain Etna, 1991-93)
       • Water Spraying
         • Is used to cool down and solidify lava flow (example: Mountain Heimaey in Iceland 1973)
     • Earthquakes
       • Earthquake proof buildings
         • Using cross bracing, counter-weights, ball bearings and rubber foundations help stabilise buildings
           • Transamerica pyramid-San francisco
     • Both Volcanoes and Earthquakes
       • Land use planning
         • Ensures that buildings are not built too high or too close to a volcano.
       • Emergency Services
         • Need to be equipped and trained to deal with hazards effectively
       • Education
         • Make sure that people know what to do when a hazard occurs (e.g: Disaster Day in Japan is 1 September)

6. Predicting Tectonic Hazards

   • Prediction Instruments
     • Tiltmeters and Lasers
       • Measure the slope of the land (check how steep it is)
     • Seisometer
       • Measure the seismic waves (an elastic wave) produced from an earthquake
     • GPS and Satellite images
       • Monitor the bulging (shape) of volcanoes and changes in ground heat (for example: Mountain St Helens, 1980)
     • Chemical Sensors
       • Measure changes in gases (carbon dioxide and sulphur dioxide) which can indicate magma activity below the ground