P1.20-P1.22 Earthquakes
- Created by: Natasha Granville
- Created on: 24-05-16 12:03
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- Earthquakes
- Seismic waves
- generated by earthquakes or explosions
- P waves
- primary
- faster
- travel through liquids and solids
- crust, mantle and core
- S waves
- secondary
- transverse
- only travel through solids
- slower
- reflected and refracted by rocks at boundaries between the crust, mantle and core
- travel on a curved path
- because the properties of rocks gradually change with the depth
- so the waves gradually refract upwards on a curved path
- when there is a sudden change in density waves are refracted sharply and may be reflected
- because the properties of rocks gradually change with the depth
- Detecting earthquakes
- 3 seismometers needed to locate epicentre
- seismometers are devices that detect earthquakes
- cant predict
- don't know how big the forces acting on the tectonic plates are
- don't know the amount of friction on the plates or how strong they are so can't predict when they will break
- time between arrival of first P wave and first S wave can be used to work out how far away from a seismometer an earthquake occured
- 3 seismometers needed to locate epicentre
- Seismic waves
- convection currents in the mantle
- plates move in relative motion
- plates don't slide past each other smoothly due to friction
- friction builds
- sudden jolt
- Earthquakes
- Seismic waves
- generated by earthquakes or explosions
- P waves
- primary
- faster
- travel through liquids and solids
- crust, mantle and core
- S waves
- secondary
- transverse
- only travel through solids
- slower
- reflected and refracted by rocks at boundaries between the crust, mantle and core
- travel on a curved path
- because the properties of rocks gradually change with the depth
- so the waves gradually refract upwards on a curved path
- when there is a sudden change in density waves are refracted sharply and may be reflected
- because the properties of rocks gradually change with the depth
- Detecting earthquakes
- 3 seismometers needed to locate epicentre
- seismometers are devices that detect earthquakes
- cant predict
- don't know how big the forces acting on the tectonic plates are
- don't know the amount of friction on the plates or how strong they are so can't predict when they will break
- time between arrival of first P wave and first S wave can be used to work out how far away from a seismometer an earthquake occured
- 3 seismometers needed to locate epicentre
- Seismic waves
- Earthquakes
- sudden jolt
- friction builds
- plates don't slide past each other smoothly due to friction
- plates move in relative motion
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