The Richter scale is used to determine the intensity of earthquakes, and a seismograph is a device that shakes with the ground during an earthquake. This movement is recorded by using ink to draw lines on paper that is constantly being moved by a motor.
The Richter scale measures factors of 10, which means an earthquake measuring 5.0 is ten times stronger than an earthquake measuring 4.0. Since humans can't feel earthquakes under 2.0, an earthquake is usually only noticed by the recordings of a seismograph. To prevent false recordings from nearby traffic or other artificial ground-shaking events, seismographs are usually anchored to bedrock to ensure an accurate reading. The largest recorded earthquake occurred in Chile in 1960 and registered a 9.5 on the Richter scale.