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Geography A Level Physical > Seismic Hazards > Flashcards

Flashcards in Seismic Hazards Deck (7)
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1
Q

What is seismicity?

A

Seismicity is the earth shaking, can be human induced

2
Q

How do seismic waves form?

A
  • pressure builds where two plates meet
  • sudden pressure release due to rock failure
  • waves cause the ground to shake
  • intensity of shaking affected by focus depth
3
Q

How do tsunamis form?

A
  • form at subduction zones, where oceanic plate is forced down due to plate tectonic forces
  • plate lowers into mantle, causing overriding plate to be distorted
  • there is a buildup of energy until it exceeds frictional forces between plates
  • as a result, overriding plate snaps back into unrestrained position
  • gives a push to overlying water, displacing it and it races away from epicentre
4
Q

What is liquefaction?

A

This is the mixing of sand or soil and groundwater during the shaking of a earthquake. It causes the ground to become soft and unstable.

5
Q

What are landslides?

A

Destabilising of cliffs or slopes as a result of ground shaking. Common in highland areas.

6
Q

Where do seismic events occur?

A

They occur close to plate margins as this is where a lot of ground movement occurs.

7
Q

What is a tsunami?

A

It is a large ocean wave caused by the sudden motion on the ocean floor