Earthquakes are measured using the Richter scale. It was developed in 1935 by Charles Richter and Beno Gutenberg at the California Institute of Technology. This scale uses numbers from 1 to 10 to measure the intensity of an earthquake. Each increase of one point on the scale means a ten-fold increase in the strength of the earthquake. So a level 5.0 earthquake is ten times stronger than a level 4.0 earthquake. The Richter scale works by measuring vibrations around the epicentre of an earthquake.