Plate Tectonics

• Plate Tectonics


  A scientific theory that explains how major landforms are created as a result of Earth's subterranean movements
• Plate Tectonics


  • Explains many phenomena, including mountain-building events, volcanoes, and earthquakes
  • The lithosphere is broken into large rocky plates that lie on top of a partially molten layer of rock (asthenosphere) that move relative to each other at different rates (2 to 15 cm or 1 to 6 inches per year) due to the two's convection
• Tectonic Plate Boundaries

  • Divergent Plate Boundaries
  • Convergent Plate Boundaries
  • Transform Plate Boundaries
• Divergent Plate Boundaries

  1. Spreading

  2. Constructive (ridge/rift)

  3. Can trigger volcanic activity
• Convergent Plate Boundaries

  1. Subduction

  2. Destructive (trench)

  3. Can trigger volcanic activity
• Types of Convergent Plate Boundaries

  • Oceanic to Oceanic Convergence
  • Oceanic to Continental Convergence
  • Continental to Continental Collision
• Oceanic to Oceanic Convergence

  Subduction of oceanic lithosphere under another oceanic lithosphere
• Oceanic to Continental Convergence


  Subduction of oceanic lithosphere under a continental lithosphere
• Continental to Continental Collision

  Two pieces of continental lithosphere meet so instead of subducting, they shorten
• Transform Plate Boundaries

  1. Lateral sliding

  2. Conservative

  3. Cannot trigger volcanic activity
• Earthquakes


  Any sudden shaking of the ground caused by the seismic waves through Earth's rocks
• Seismic Waves


  Produced when some form of energy stored in the Earth's crust is suddenly released, usually when masses of rocks straining against one another suddenly fracture and slip (faults)<|>Energy that travels through the Earth and is recorded using a seismograph (not to be confused with the seismometer used to measure magnitudes)
• Faults


  Underground ruptures, fractures, or breaks in the Earth's crust<|>Boundaries of continental plates and oceanic crusts are considered as crusts<|>Blocks of Earth's crust that meet together
• Types of Faults

  • Shearing Stress (causes masses of rock to slip or move side-by-side)
  • Tension Stress (stretches the rock and causes them to move away from each other)
  • Compression Stress (pushes rocks together)
• Types of Earthquakes

  • Tectonic (produced by sudden movement along faults and plate boundaries)
  • Volcanic (produced by the movement of magma beneath volcanoes)
  • Collapse (triggered by constant mining activities and drilling into massive rocks)
  • Explosive (induced by the release of enormous amounts of nuclear energy)
• Focus


  Place inside the Earth's crust where an earthquake originates<|>Seismic waves move forward from this point in all directions
• Hypocenter


  Location below the Earth's surface where the earthquake starts
• Epicenter


  Location directly above the hypocenter on the surface of the Earth
• Foreshocks


  Smaller earthquakes that happen in the same place as the larger earthquake
• Waves


  Disturbance that travels or propagates from the place where it was created<|>Transfers energy from one place to another but do not transfer mass
• Wave Parts

  • Crest
  • Trough
  • Wavelength
  • Amplitude
• Crest


  Highest point of a wave
• Trough


  Lowest part of a wave
• Wavelength


  Distance between two succeeding waves
• Amplitude


  Maximum displacement moved by a point on a vibrating body<|>Positive - from rest to crest<|>Negative - from rest to through
• Seismic Waves

  • Body Waves
  • Surface Waves
• Body Waves

  • Primary/P Waves
  • Secondary/S Waves
• Primary/P Waves


  Longitudinal; parallel; moves back and forth; felt first; travels in the mantle
• Secondary/S Waves

  Transverse; perpendicular; moves up and down; felt second (slower than P Waves); only travels through solid
• Surface Waves

  Why the ground shakes
• Types of Surface Waves

  • Rayleigh Waves
  • Love Waves
• Rayleigh Waves


  Causes the rocks to move up and down and particles to roll one another
• Love Waves


  Causes the Earth's ground to move side by side
• Volcanoes


  Geological formations where molten rocks, ash, and gases escape from beneath the Earth's surface
• Magma


  Molten rocks below the surface of the Earth that rise in volcanic vents but are called lava once the volcano erupts
• Magma formation


  After cooling, liquid magma may form crystals of various minerals until it becomes completely solid and forms an igneous or magmatic rock
• Sources of magma

  • Island arcs
  • Magma hotspots
  • Mid-oceanic ridges
  • Continental arcs
  • Rift zones
• Locations of volcanoes

  • Converging plates
  • Diverging plates
• Converging Plate

  Volcanoes found in the Pacific Ring of Fire
• Diverging Plate

  Volcanoes in the Mid-Atlantic Ridge