For those who grew up in earthquake affected countries, the Richter scale was a constant refrain, but the mathematical formula for measuring quakes is no longer widely used by scientists or the media.
The more modern formula for Earthquake measurement is the moment magnitude scale. Unlike the Richter scale, it captures all the different seismic waves from an earthquake, allowing experts to make more precise measurements.
Using seismographs – instruments that measure the shaking ground – scientists can accurately calculate the location, time and magnitude of the earthquake.
From these measurements, earthquakes are assigned a class. An increase of one number means the quake’s magnitude is ten times greater than the number prior.
In the past week, two earthquakes have struck off the coasts of Greece and Japan, both measuring in at 6.7 on the moment magnitude scale.
The quake off the west coast of Greece damaged buildings and killed at least one person. In Japan, the earthquake caused a small tsunami but no major damaged was reported.
Watch more on how fault lines grinding together can birth what is known as megaquakes.