[jerryem]

I would like to disagree with you Sir, with the modern explosive technology it would not be difficult to create such a blast, I personally know of an explosive that has a 500 to 1 greater impact than nitroglycerin, 25 tonnes of this used as a implosion ( not explosion )would create a good earthquake.

[kitd-fohs]

Au contraire, please read up on the Divine Strake project which utilizes a 700 ton ANFO subterranean charge designed to mimic low-yield subterranean nukes to destroy bunker complexes. That would indeed rattle some cages.

http://www.globalsecurity.org/wmd/ops/divine-strake5.htm

[NinoFan]

So instead of a nuke test involving a primitive weapon that didn't work as well as they planned (not a big shock for a first time nuke test), you're suggesting that North Korea used an advanced non-nuclear technique that is still in the testing phase here in the US just because it wanted to fool us into thinking it had capabilities we had over 50 years ago?

[NinoFan]

To add to my previous point, a Nuke has a commonly recognized signature on a seismograph. We have that here. Either it was a nuke test that didn't work as well as planned or it was an event involving a rather advanced method to produce a seismograph that looked like that of a small nuke test. I personally think the first is more likely.