The Richter scale measures the strength of an earthquake. The scale is logarithmic, so an earthquake of magnitude 6 is ten times more powerful than one of magnitude 5, and 100 times more powerful than a magnitude 4 earthquake. It was named after its inventor, Charles Richter, who developed the measure in 1935. The largest recorded earthquakes measure around 9 on the Richter scale.
- Schoch, Robert; McKinney, Michael L. & Yonavjak, Logan (2007). Environmental Science: Systems and Solutions, 4th edition. Jones & Bartlett Publishers. p. 135. ISBN 978-0-7637-4262-1.