Overview of Earthquakes
Geography: KS3, topic 11.3.1
What is an Earthquake?
When plates move past each other, waves (vibrations) are created. There are different aspects of an earthquake:
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Epicentre
- The epicentre is the point directly above the centre of the earthquake on the earth’s surface.
Focus
- The focus is where the pressure is released underground and where the energy radiates out from.
- This is the place with the strongest waves that cause the most damage.
Shock (seismic) waves
- Energy is released from the focus in shock waves (called seismic waves).
- The most damage will occur at the places where the shock waves are strongest (closest to the epicentre).
Earthquakes
An earthquake is a sudden or violent movement within the Earth’s lithosphere that is followed by a series of shocks. An earthquake happens when the Earth’s tectonic plates move and cause the ground to shake.
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Earthquakes can happen at all plate margins
- At divergent margins, pressure can build up from cracks in the plates when they move apart. This can cause earthquakes.
- At convergent margins, a plate can get stuck as it moves under another. This can cause earthquakes.
- At conservative margins, there can be friction between plates because they aren't smooth. This can cause earthquakes.
Plates forcing their way past each other
- As plates move past each other, pressure builds up from the friction between them.
- When the pressure is sufficient, the plates give way. The tectonic plates will surge past each other and the ground will shake from this violent movement.
Test yourself on Overview of Earthquakes
What do we call the point directly above the centre of an earthquake on the earth’s surface?
Where can earthquakes happen?
What are earthquakes?