The Richter Scale (earthquakes)
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| Earthquake Magnitude | Effects |
| M = 1 – 2 | Recorded on local seismographs, but generally not felt |
| M = 3 – 4 | Felt, but no damage |
| M = 5 | Felt widely, slight damage near epicenter |
| M = 6 | Damage to poorly constructed buildings and other structures for several miles / km |
| M = 7 | "Major" earthquake causing extreme damage for 60 mile / 100 km |
| M = 8 | "Great" earthquake causing extreme damage for 600 mile / 1000 km |
| M = 9 | Rare great earthquake, major damage over a large region over 600 miles / 1000 km |
The Richter scale is logarithmic, this means that an increase of 1 magnitude unit represents a factor of ten times in amplitude. The seismic waves of a magnitude 6 earthquake are 10 times greater in amplitude than those of a magnitude 5 earthquake. However, in terms of energy release, a magnitude 6 earthquake is about 31 times greater than a magnitude 5.
