Real-time Earthquake Map – Click Here to Visit
Thousands of earthquakes occur each year, yes thousands, but not everyone of them felt or cause damage. Only Quakes that are above 5.0 Magnitude cause damage. The United States Geology Survey website provides a real-time Earthquake map through which it is possible to watch earthquakes of various magnitudes occurring in various parts of the world in real-time.
Richter Scale
The energy contained in an earthquake is measured using a Richter Magnitude Scale and this magnitude decides the impact of the earthquake. The impact also depends on many factors like origin of the quake, type of the fault etc.,
Here is a table depicting the Richter Magnitudes
Source: http://en.wikipedia.org/wiki/Richter_magnitude_scale