The Japan Times:
Let us say you are North Korea and you have this nuclear device you really want to test. And let us say you would rather some of the more sensitive details remain private.
Physicists, geologists, imagery analysts, some of the best militaries in the world, monitoring posts set up by non-proliferation organizations — beating the technology arrayed against you will be no mean feat.
But, it turns out, they might not actually find very much.
North Korea has proven over the past 10 years it can be exceptionally difficult to determine from a properly set up nuclear test some of the most basic details an adversary would want to know.
Concern is growing another test may be looming because of heightened activity at the North’s testing site, though activity can be staged to create a false alarm.
Here is a look at how the North does its testing, and why they keep it up.
Mount Mantap tunnels
North Korea has conducted five nuclear tests, all in the depths of a remote, granite peak called Mount Mantap.
The location of its testing site is no secret.
It is a favorite target of spy satellites. North Korea featured it in a 2010 propaganda film.
About halfway up the 2,205-meter (7,200-foot) mountain are three main entrances, or portals, into horizontal tunnels stretching a kilometer (about a mile) or more into the mountain. Studies of the tunnel used for the second test, which was conducted in 2009 and featured in the propaganda film, suggest it has the shape of a fishhook. Pakistan used a similar design.
The device was placed at the farthest end of the tunnel, which used the angles and corners of the “hook” section to deflect and absorb as much of the blast as possible. To further optimize absorption, the tunnel had nine or 10 sharp corners with bulkheads and dead-end “debris traps.”
