"earthquakes in north korea"

Zoom out a bit and you can see the "Hwasong Gulag."

https://plus.google.com/101019651244056999126/about?gl=us&#3...

The reviews are, well, you know. Welcome to the internet.

The USGS compiles seismic hazard maps based on historical data for this very purpose:

http://neic.usgs.gov/neis/bulletin/neic_c000f5t0_w.html

As you keep zooming out[1] of the location of this nuke, till you see atleast a whole portion of the earth, you will realize that the existence of this nuke (or the concept of where/how it will be used) is unnecessary.

[1]http://goo.gl/maps/TNfuD (Thanks to HN user jonsherrard for the link)

The idea is basically this:

An exploding buried nuke will send energy in all directions, thus the first movement of the ground is away from the epicenter for all measurement stations around.

An earthquake usually comes about because tension between different areas release, and in that case one part of the ground will start their movement away from the epicenter, the other part will start into the direction of the epicenter.

However, one might need measurement stations covering the whole globe to detect it this way.

edit: Hm, I can't find the image that I've seen in a plate tectonics book a year ago, but here's a plot from a model: http://www.wlandry.net/Projects/Gamra If you look at the arrows in light blue, you can see that some point into the direction of the epicenter while some point away, thus it's an earthquake and not a nuke.

Wolfram Alpha can't be trusted then.