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Our Earth
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Plate Tectonics

• Tectonic plates
• large pieces of the crust and part of the mantle
  called the lithosphere
• seven very large ones and lots of small ones
• constantly moving/floating (1-16cm/year) on the
  plastic part of the mantle because of convection
  currents in the soft rock underneath them
• this is called continental drift

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Plate Boundaries

• Divergent boundaries
• plates move apart
• Mid-ocean ridges are mountains created by the
  rising lava
• Divergent Boundary

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Mid-ocean ridges
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• Convergent boundaries
• plates come together
• can develop chains of volcanoes, mountains, and
  earthquakes
• Continental Drift - Tetrionic Plates
• subduction is where the denser plate dives under
  another
• Juan de Fuca plate is diving under the North
  American plate (this is not good)
• Animation of Earthquake and Tsunami in Sumatra
• Stuck in tsunami

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For most recent EQ -- http//www.pnsn.org/recenteq
s/latest.htm
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Earthquakes

• energy is released as plates slip along a fault
  line
• the focus is where the slippage occurs
• the epicenter is the point on the surface above
  the focus

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• measured using the Richter Scale
• each number increased on the scale is about 10
  times the amount of ground shaking and 30 times
  more energy

- the building can withstand winds and typhoons
of up to 200km/h(with the top swaying by a
maximum of 75cm/0.3inches)and earthquakes of up
to 7 on the Richter scale
Built to withstand 200 mph winds and an
earthquake of up to 9.5 magnitude.
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Earthquake Waves

• Primary / Longitudinal / P waves
• fastest waves
• travel out in all directions from the epicenter
• compress the earths crust

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• Secondary / Transverse / S waves
• slower than P waves
• travel up and down
• travel out in all directions from the epicenter

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• Surface waves
• move only across the earths surface
• causes the most damage because of a circular
  motion caused by up and down AND back and forth
  motion

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Weathering and Erosion - breaking rocks apart

• Physical (mechanical) weathering
• glaciers moving, water (ice) expanding, wind, and
  plant roots
• erosion wind and water can loosen and move
  sediment
• deposition the sediment then builds up somewhere
  else
• Chemical weathering
• O, H2O, and CO2 chemically react with many
  minerals forming new compounds

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