A Bomb or a Dud?

A BOMB OR A DUD?….Here’s what the BBC says about the North Korean nuclear bomb test:

The size of the bomb is uncertain. South Korean reports put it as low as 550 tons of destructive power but Russia said it was between five and 15 kilotons.

And the LA Times:

One intelligence official, speaking on condition of anonymity, said U.S. intelligence agencies detected an explosive event in North Korea with a force of less than a kiloton. Historically, the types of devices used in initial nuclear tests have yielded several kilotons of force.

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.

I agree. There just seem to be several oddly suspicious things about the North Korean announcement.