Earthquakes

Location and Cause 

Earthquakes are distributed along plate margins. The majority of earthquakes happen along the west coast of America, as this is where the Nazca and South American plates meet. Furthermore, many earthquakes occur near Japan in the Pacific Ocean, as this is where the Eurasian Plate meets the Indo - Australian Plate. There are hardly any earthquakes along the Antarctic Plate Boundary. 

Why do Earthquakes occur? 

Destructive Margins

The pressure resulting from the sinking of the sub ducting plate and its subsequent melting can trigger strong earthquakes as this pressure is periodically released. 

Constructive Margins

Here earthquakes tend to be less severe than those at destructive or conservative plate margins. This is because the friction and pressure caused by the plates moving apart is less intense than at destructive plate margins. 

Conservative Margins

Where the plates slide past each other, the plates tend to stick for periods of time. This causes stresses and pressure to build. The release of the pressure occurs in a sudden, quick release of the plates and often results in powerful earthquakes. 

1. Plates move past each other die to convection currents
2. The edges of the plates are jagged and get locked together
3. The pressure between the plates builds up and eventually becomes too much for the plates to stand
4. One of the plates slips, causing a jolting movement and releasing shock waves 
5. This causes an earthquake

Key terms

Focus: The point in the earth's crust where the earthquake begins

Epicentre: The point at the earth's surface directly above the focus

Shockwaves: Seismic waves generated by an earthquake that pass through the earth's crust