2.1+-+Plate+Tectonics

__From the syllabus__
Candidates should be able to:


 * Describe the general distribution of fold mountains, volcanoes and earthquakes and explain how this distribution is related to movements at plate boundaries.
 * Show a basic understanding of plate tectonics, describing the global pattern of plates, their structure, and be aware of plate movements and their effects – plates moving away from each other (sea floor spreading), plates moving towards each other (subduction) and plates sliding past each other.
 * Demonstrate an understanding of the main features of volcanoes (and their eruptions) and earthquakes.
 * Demonstrate an understanding that the natural environment presents hazards and offers opportunities for human activities. Reference should be made to the hazards posed by volcanic eruptions, earthquakes.

**__Key term list__**

 * Plate Tectonics** – the theory and study of plate formation, movement, interactions and destructions.
 * Fault** – A fracture in the earths crust along which rocks move relative to each other.
 * Convection Currents** – the transfer of heat from the earths interior to the surface through the asthenosphere.
 * Crust** – The outermost layer of the lithosphere.
 * Plates** – large areas of land and sea bed. Each plate is slowly moving across the globe
 * Mantle** – The main bulk of the solid earth, between the crust and the core.
 * Core** – The central part of the earth below a depth of 2900km, believed to consist of Iron and Nickel.
 * Plate Boundaries / Margins** – where two plates meet.
 * Constructive Plate Boundary** – where two plates move away from each other and new oceanic crust is formed
 * Sea floor Spreading** – The process by which new ocean floor is created at ridges as two plates diverge.
 * Divergence** – two plates moving away from each other
 * Destructive Plate Boundary** – where two plates move towards each other and oceanic crust is destroyed by subduction.
 * Subduction** – the sinking of an oceanic plate beneath an overriding plate occurring at convergent plate boundaries.
 * Conservative Plate Boundary** – where two plates move sideways past each other and land is neither created nor destroyed.
 * Collision Plate Boundary** – where two continental plates collide, resulting in the formation of fold mountains.
 * Convergence** – two plates moving towards each other
 * Oceanic Ridge** – An underwater mountain range developed at a divergent plate boundary where magma rises up through a cracking and widening ridge.
 * Oceanic Trench** – A long depression in the ocean floor at the junction of two plates, where one is being subducted under the other.
 * Fold Mountains** – mountains formed by the buckling of the earths crust, often associated with destructive or collision boundaries.
 * Earthquake** – The violent movement of the ground caused by sudden movement along a fault releasing seismic waves.
 * Seismograph** – measures and records the intensity of an earthquake
 * Mercali Scale** – a measurement of the intensity of an earthquake (based on observations during the earthquake, and the damage caused)
 * Richter Scale** – scale used to measure the magnitude of earthquakes (the size of the seismic waves).
 * Magma** – molten rock, gas and steam.
 * Lava** – molten rock on the earth’s surface.
 * Liquefaction** – ground turning to a liquid state as water is shaken up from below.
 * Primary Effects** - the direct effects of an earthquake – e.g. a building collapsing
 * Secondary Effects** – the indirect effects of an earthquake e.g. fire, tidal waves and disease.

Case Studies

 * Kobe, Japan (MEDC earthquake example) (textbook p. 270)
 * Tangshan, China (LEDC earthquake example) (pdf file)
 * Mt. St. Helen's, USA (MEDC volcano example) (textbook p. 266)
 * Mt. Merapi, Indonesia (LEDC volcano example) (textbook p. 268)