Earthquakes can be recorded through the use of an instrument known as seismographs. The recording made by this instrument is known as a seismogram. A seismograph has a base that sits on the ground and a heavy weight that hangs in the middle. When an earthquake occurs the base of the seismograph shakes and the weight stays still. The spring above the weight absorbs all the movement . Below is a picture that explains how the seismogram is recorded.
How are Earthquakes recorded?
Richter Scale
The Richter scale is used to assign a magnitude number to the amount of energy released from an individual earthquake. Charle Francis Richter and Beno Gutenburg developed the Richter scale together. Below is a table explaining the different magnitudes on the Richter scale.