The year 2017 have seen some of the most devastating earthquakes of the decade mostly shaking the Western Hemisphere. In simple words an earthquake is the shaking of the surface of the earth as a result of the release of energy in the earth's lithosphere that creates seismic waves.
The intensity of an earthquake is measured in Mercalli intensity scale which measures the effects of the quake based on empirical and observed data.
The magnitude of earthquake is measured by Richter scale which assigns a number to quantify the size of an earthquake. It is a base 10 logarithmic scale invented by Charles Richter in 1930s.
It was replaced by the moment magnitude scale in 1970, that is currently being used by the US Geological survey.