Layers of The Earth
- The Earth's surface is made up of a series of large plates (like pieces of a giant jigsaw puzzle).
- These plates are in constant motion travelling at a few centimetres per year.
- Convection currents beneath the plates move the plates in different directions.
- The source of heat driving the convection currents is radioactive decay which is happening deep in the Earth.
Three Ways that Plates Move
- destructive plate boundary - two plates move together
- constructive plate boundary - two plates move apart
- conservative plate boundary - two plates move side by side
Earthquake Key Terms
- Earthquake - violent shaking of surface cause by sudden release in tension
- Epicentre - Point on Earth's surface directly above surface where earthquake is felt
- Seismic Wave Energy - Energy released as a shock through crust
- Focus - Point inside crust where built up pressure is released
- Faults - Large cracks in crust
- Magnitude - Unit of measurement for how much energy is release by an earthquake
- Richter Scale - Scale used to measure magnitude of earthquake
- Tsunami - a giant wave or series of large waves in the ocean
- Liquefaction - process in an earthquake when the movement of energy waves causes the ground to act like a liquid
- Intensity - a measure of the effect of an earthquake
- Aftershock - smaller earthquakes that occur after main quake
- Foreshock - Smaller earthquakes that occur prior to earthquake
Responding to Earthquakes
- Predict - tiltmeters (change in gradient of volcanoes)
- Protect - sit under a table or inside a cupboard
- Prevent - redesign buildings to be earthquake proof.
San Andreas Fault Line
Earthquakes occur quite often along the San Andreas Fault Line because the two plates - North American Plate and the Pacific Plate are of the conservative type of plate boundary which means that they moev side by side to create a lot of friction. Moreover, they move at different speeds; the Pacific Plate moves at 3cm/yr while the North American Plate moves at 1.4cm/yr. Eventually, the friction causes a lot of pressure to…