tectonic processes

• what is the tectonic plate theory?

  the movement of the plates and the activity inside the earth
• what are the tree types of plate margins?

  destructive, constructive, and conservative
• what happens at a destructive plate margin?

  two plates move towards one another
• what happens at a destructive plate margin where a oceanic plate meets an continental plate?

  the denser oceanic plate is subducted and destroyed, creating gas-rich magma (volcanoes and ocean trenches occur here)
• what happens at a destructive plate margin where two continental plates meet?


  the ground is folded upwards (creating fold mountains)
• what does subducted mean?

  when an oceanic plate runs into a continental and forced beneath it, down into the mantle
• what happens at a constructive margins?

  two plates are moving away from each other, magma rises from the mantle to fill the gap and cools creating new crust.
• what happens at conservative margins?

  two plates move sideways past eachother, or in the same direction but at diffrent speeds
• what plate(s) margins are volcanoes formed at?

  destructive and constructive
• what plate(s) margins are earthquakes formed at?

  all three (destructive, conservative, constructive)
• how are volcanoes formed at destructive plate margins?

  the denser ocianic plate is pushed into the mantle where it melts. magma forms, which rises through vents (cracks in the crust). the magma erupts (becoming lava when it reaches the surface).
• how are volcanoes formed at constructive plate margins?

  magma rises to fill the gap left by the plates moving apart.
• how is tension built up to make an earthquake at a destructive plate margin?

  as one plate gets stuck as it moves past the other
• how is tension built up to make an earthquake at a constructive plate margin?

  tension builds along cracks in the plates as they move away from eachother
• how is tension built up to make an earthquake at a conservative plate margin?

  as plates that are grinding past eachother get stuck
• what happens after tension is built at a plate margin to make a earthquake?

  the plates eventually jerk past each other, sending out shock waves (these vibrations are the earthquake)
• what is the focus of an earthquake?

  the point in the earth where the earthquake starts.
• shock waves are stronger near the focus of an earthquake and cause more damage.
• what is the epicenter of an eathquake?

  the point on the earths surface straight above the focus
• what is the the moment magnitude scale?

  it measures the amount of energy released by an earthquake (magnitude), it is logarithmic (e.g 7 would cause ten times the amount of ground shaking than 6)