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.