Don,

Your calculation is a bit off because the energy in the explosion is mostly at frequencies higher than 1 Hz, not down at 20 s period where the Ms scale is measuring. It takes about an M6.5 or 7 to match the energy radiated in a large nuclear test. See the link.

But our conclusion stands that the energy released in explosions is minor compared to that in large earthquakes.

Another twist is that much MORE energy is released near the earthquake as heat and cracking, which does not appear in the seismic waves.

John

• look most of the way down for the table