What does +1 magnitude mean?
≈32×
More
energy
Each step up the scale releases about 32 times the energy of the step below. The shaking itself is about 10 times larger. A “magnitude 6.0” is one step above a 5.0 and one below a 7.0.
Step by step
| Magnitude | Shaking on a seismograph | Energy released |
|---|---|---|
| Magnitude 5 | 1× | 1× |
| Magnitude 6 | 10× | 32× |
| Magnitude 7 | 100× | ≈1,000× |
| Magnitude 8 | 1,000× | ≈32,000× |
10×bigger shaking per step
32×more energy per step
Why 32 and not 10?
Two different things grow when you go up a step. Which one someone means is the whole trick.
10×
The shaking
The scale is built so that each step makes the wiggle on a seismograph 10 times taller.
32×
The energy
Energy grows faster than the wiggle: 10 raised to the power 1.5, which is about 32.
So “a 7 is 10 times bigger than a 6” is true of the wiggle, but it understates the energy. Steps multiply: two steps up is 32 × 32, about 1,000 times the energy.
Here’s the idea
Magnitude 7 is not a bit stronger than 6. It is about 32 times the energy.
Go deeper
That’s the click. This page explains the number, not how it’s measured, or why a quake’s damage depends on much more than its magnitude. The US Geological Survey covers that: USGS, “Earthquake Magnitude, Energy Release, and Shaking Intensity”.