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Flashcards in Seismic Hazards Deck (7)
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What is seismicity?

Seismicity is the earth shaking, can be human induced


How do seismic waves form?

- 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


How do tsunamis form?

- 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


What is liquefaction?

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.


What are landslides?

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


Where do seismic events occur?

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


What is a tsunami?

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