HOW EARTHQUAKES HAPPEN
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- Earthquakes are Earth's vibrations in response to rupturing and sudden movement of rocks that have been strained/ deformed beyond their limit.
- These forces are named stresses.
- They occur along faults - cracks in the Earth's surface (lithosphere) were rocks move past each other (displaced)
- 90% of earthquakes are caused by rocks rupturing because of these tectonic stresses.
- CAUSES OF EARTHQUAKES
- The earths crust is like a jigsaw puzzle comprising of tectonic plate that slowly roam the face of the planet. The plate boundary of these tectonic plates are rough and can easily be stuck and cause them to break and release the plate.
- ELASTIC REBOUND HYPOTHESIS
- AFTERSHOCKS & FORESHOCKS
- ELASTIC REBOUND HYPOTHESIS- elastic energy stored in rocks rapidly released because it has been subjected to great forces. - when the force in the rock is too strong it breaks suddenly causing earth to vibrate (earthquake).
- AFTERSHOCK- small earthquake that occurs after main earthquake.
FORESHOCK- small earthquake that occurs before the major earthquake
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- FOCUS- the point in the Earth where the earthquake begins.
- EPICENTRE- the place on the Earth's surface which is directly above the focus
- SEISMIC WAVES- waves of energy that spread out in all direction when the fault ruptures.