Earthquake Magnitude Explained: What the Numbers Actually Mean
Updated 2026
When you see "magnitude 5.2" on a live tracker, it's easy to assume a 6.2 is "just a bit bigger." It isn't. Magnitude scales are logarithmic, and understanding that changes how you should read every earthquake report you see.
What "logarithmic" means in practice
Each whole-number step up the magnitude scale represents roughly 10 times greater ground motion (amplitude) and, more importantly, about 32 times more energy released. So a magnitude 7.0 earthquake doesn't release "40% more" energy than a 6.0 — it releases roughly 32 times more. A magnitude 8.0 releases roughly 32 × 32 ≈ 1,000 times more energy than a 6.0.
The scale used today: Moment Magnitude (Mw)
Older news reports sometimes reference the "Richter scale," but modern agencies including USGS primarily use the Moment Magnitude Scale (Mw) for anything above about magnitude 3.5–4, because it more accurately reflects the total energy released for large earthquakes. For smaller, local events, related scales are still used. In practice, the number you see reported behaves the same way for a general audience: bigger number, dramatically more energy.
Rough magnitude reference table
| Magnitude | Typical effect | Approximate frequency worldwide |
|---|---|---|
| Under 2.5 | Usually not felt, only recorded by instruments | Millions per year |
| 2.5 – 4.9 | Often felt, rarely causes serious damage | Tens of thousands per year |
| 5.0 – 5.9 | Can cause damage to poorly built structures | ~1,000+ per year |
| 6.0 – 6.9 | Can be destructive in populated areas | ~100–150 per year |
| 7.0 – 7.9 | Major earthquake, serious damage over large areas | ~10–20 per year |
| 8.0+ | Great earthquake, devastating over very large areas | ~1 per year or less |
Frequency figures are long-term global averages compiled by USGS and vary year to year.
Why magnitude alone doesn't predict damage
Two earthquakes of the same magnitude can have wildly different real-world impact because of:
- Depth: Shallow earthquakes (roughly under 70 km deep) concentrate more shaking at the surface than deep ones of the same magnitude.
- Distance from population centers: A magnitude 7.5 quake under an uninhabited ocean trench may cause no casualties, while a shallow 6.0 directly under a city can be catastrophic.
- Local geology: Soft sediment and reclaimed land amplify shaking compared to solid bedrock.
- Building codes and construction quality: The same shaking intensity causes far less damage in structures built to modern seismic codes.
See it live
Head back to the live earthquake tracker to see current magnitudes worldwide, or read our earthquake safety guide for practical preparedness steps.