The energy released during an earthquake causes the ground to shake. If you are close to the epicenter of a moderate quake, the shaking is more severe than if you were farther away. Scientists have developed many scales to measure the intensity of earthquakes. Two common ones are the Richter Scale and Modified Mercalli Scale. The Richter Scale measures the size of the waves produced by the earthquake, hence the energy it releases. The Richter Scale is absolute; seismologists will derive the same Richtermagnitude wherever they measure the earthquake. The Modified Mercalli Scale describes what a person feels during an earthquake. This scale is relative; it changes depending on how far you are away from the epicenter.