Tectonic hazards/Richter scale
The Richter magnitude scale is a scale of numbers to tell the power of earthquakes. American scientist Charles Richter developed the Richter Scale in 1935. His scale was based on the seismograms measured by a particular type of seismometer at a distance of 100 kilometers (62 mi) from the epicenter of earthquake.
Earthquakes that measure 4.5 or higher on the Richter scale can be detected by tools all over the world.
The scale is logarithmic, with a base of 10. The amplitude of an earthquake which scores 3.0 is about 10 times the amplitude of one that scores 2.0 while the energy that is released will increase by a factor of about 32.