eathquakes

The richter scale is of more use than the mercalli scale because the mercalli scale doesnt take into account the difference between MEDC and LEDC construction.

Epicenter - the point directly above the focuse where the earthquake is felt first at the earths surface.

Focus - the point underground where the earthquake originates from and the siesmic waves are produced.

• The causes of earthquakes.
• Earthquakes can occur at all plate margines.
• Most commonly they occur at destructive and conservative margins.
• At conservative margins, two plates move due to convection currents in the mantle and slide past each other at different speeds or different directions.
• The plates become locked and pressure builds up. 
• Eventually the plates jolt past each other and the pressure is released as seismic waves which travel from the focus.