Why the magnitude scale is logarithmic
Magnitude is not a linear scale. Each whole point up means the ground shakes about 10 times more, and the earthquake releases roughly 32 times more energy. Go up two points and that is about 1,000 times more energy. That is why a magnitude 5 and a magnitude 7 — only two numbers apart — are worlds apart in what they can do.
| Magnitude | Energy vs M5 | Example |
|---|---|---|
| M5.0 | 1× | Reference (moderate) |
| M6.0 | 32× | Strong, local damage |
| M7.0 | 1,000× | Major earthquake |
| M8.0 | 31,600× | Great earthquake |
| M9.0 | 1,000,000× | Tōhoku 2011, Sumatra 2004 |
| M9.5 | 5,600,000× | Valdivia, Chile 1960 (largest recorded) |
The comparator uses the same energy relationship — energy grows as ten to the power of 1.5 times the magnitude difference — so the ratio it shows is a real physical number, not just the gap between the labels.
For the full story on how magnitude is measured and why early figures get revised, read How Earthquake Magnitude Is Really Measured.
Frequently asked questions
How much more energy is a magnitude 7 than a magnitude 6?
About 32 times more. Each whole point of magnitude is roughly a 32-fold jump in released energy, even though the shaking amplitude only grows about tenfold.
Why is the magnitude scale logarithmic?
Because earthquakes span an enormous range of energy. A logarithmic scale keeps the numbers manageable — a single line from tiny tremors to the largest quakes ever recorded.
What is the largest earthquake ever recorded?
The 1960 Valdivia earthquake in Chile, at magnitude 9.5. It released roughly 5.6 million times the energy of a magnitude 5.
Is the Richter scale the same as moment magnitude?
Not exactly. The original Richter scale is now largely replaced by moment magnitude (Mw) for medium and large quakes, but both are logarithmic and give similar numbers for everyday earthquakes.
Does one point of magnitude mean twice the shaking?
No — it means about ten times the shaking amplitude and about 32 times the energy. The magnitude number climbs slowly while the physical effect climbs fast.