A BOMB OR A DUD?

A BOMB OR A DUD?: "There's something peculiar here. A geology professor at Yale, Jeffrey Park, emails to tell me that the updated Richter magnitude for the North Korea event is 3.5, which he calls "mighty small for a crude nuke." And that's true: it suggests a very small yield. But the odd thing is that it's actually harder to build a 1 kiloton weapon than a 5 or 10 kiloton weapon, and it's unlikely North Korea has the expertise to do this.

Was this a failed test? A 10 kiloton nuke that fizzled? Not a nuke at all? (The North Koreans seemed unusually insistent that there was absolutely no release of radiation.) Or what?

POSTSCRIPT: I should add that Jeff, who's an old high school friend of mine, stresses that 'My skepticism is not to be taken as a conclusion that North Korea is bluffing. A reliable detection of bomb-generated radionuclides would prove that they were not.' A paper he cowrote on the 1998 Indian nuclear test is here.

(Via ArmsControlWonk.com.)