Measure of the magnitude (strength) of an earthquake
Richter scale developed
1935
Determining earthquake magnitude using Richter scale
Measure amplitude of seismic waves
Richter scale
Logarithmic scale
Each whole number increase represents a tenfold increase in amplitude of seismic waves
Represents a 30 fold increase in energy released
The Richter scale has no upper limit
The greatest earthquake recorded was a 9.5 magnitude in Chile 1960
Moment magnitude scale
Measures the energy released by an earthquake more accurately than the Richter scale
Moment magnitude scale
The amount of energy released is related to the geological properties such as rock rigidity, area of the fault surface and the amount of movement in the fault
It is not used for small earthquakes
Modified Mercalli scale
Measures the intensity of the damage caused after an earthquake
Modified Mercalli scale
It relates to the ground movement to impacts that can be felt and seen to anyone in the affected location
It is a qualitative assessment based on observation and description and is therefore subjective
