[Iris7]

Nuclear devices of quite low power can be made. An high explosive deep ground burst in hard rock that would appear very much like a fractional kiloton nuclear device is not even very expensive if one has an appropriate unused deep rock mine shaft. I suspect that two or three thousand tons of conventional modern mining explosives costing a few million dollars would be hard to distinguish from a Hiroshima type bomb when fired 6,000 feet down if the charge were well tamped and constrained by a concrete filled access tunnel.

Kim Jong Il might enjoy such a jest. He could even release a video covering the building of such a device (for "peaceful mining purposes", naturally) and then set off his nuke instead.

[ruiner]

I'd be willing to bet there are subtle difference between seismic profiles of underground nuclear blasts (even small ones) and underground high explosives detonations of similar yield.

Anyone know for sure?