How much energy is in that earthquake?
The magnitude scale is logarithmic in amplitude and even steeper in energy: one point up is 32 times the energy released.
Almost exactly a magnitude 7
478 kt TNT is more than 5 of the 8 references on this page.
Reference figures are measurements and are rounded; the unit conversion behind them is exact.
| Reference | Size | Yours ÷ theirs | Note |
|---|---|---|---|
| magnitude 3 | 0.000478 kt TNT | 999,976× | Felt indoors, no damage |
| magnitude 4 | 0.0151 kt TNT | 31,745× | |
| magnitude 5 | 0.478 kt TNT | 1,000× | Damage to weak buildings |
| magnitude 6 | 15.1 kt TNT | 31.7× | |
| Hiroshima bomb | 15.1 kt TNT | 31.7× | For comparison |
| magnitude 7 | 478 kt TNT | 1× | Serious damage over a wide area |
| magnitude 8 | 15,057 kt TNT | 1/31.5 | |
| magnitude 9 | 478,011 kt TNT | 1/1,000 | Tōhoku 2011, Sumatra 2004 |
Worth knowing
- Each whole magnitude step is 31.6 times the energy. A magnitude 7 is a thousand times a magnitude 5, not 40% more.
- The 2011 Tōhoku earthquake released roughly the energy of 30 000 Hiroshima bombs, and shifted the Earth’s axis by about 17 cm.
Frequently asked
How much stronger is a magnitude 7 than a 6?
Ten times the ground motion and about 32 times the energy. That is why the damage difference is so much larger than the number suggests.
Is the Richter scale still used?
Not by seismologists. It saturates above about magnitude 7, so moment magnitude replaced it in the 1970s. News reports still say "Richter" out of habit.
How to read this
Energy figures are radiated seismic energy, which is a small and uncertain fraction of the total released.