On a machine called a seismograph, the Richter scale measures the magnitude of an earthquake, i.e., the size of the ground waves generated at the earthquake’s source. The scale was devised by American geologist Charles W. Richter (1900–1985) in 1935. Every increase of one number means a tenfold increase in magnitude.
| Richter Scale |
| Magnitude |
Possible Effects |
| 1 |
Detectable only by instruments |
| 2 |
Barely detectable, even near the epicenter |
| 3 |
Felt indoors |
| 4 |
Felt by most people; slight damage |
| 5 |
Felt by all; damage minor to moderate |
| 6 |
Moderately destructive |
| 7 |
Major damage |
| 8 |
Total and major damage |
