Political Cortex: Brain Food for the Body Politic

Nuclear tests generate energy equivalent to a small earthquake, and as a result are visible on siesemographs.  Large tests can be seen around the world.  Even small tests (by which I mean something on the scale of the US "Trinity" test) are visible over a fairly broad area.

The 3.58 magnitude event that South Korean sources initially reported is not too far from what would be expected with a small device.  However, let's look at some other siesemic stations.

This is data from Yuzhno Sakhalinsk, Russia.  It's about 1000 miles, or 1600 kilometers, from the supposed North Korean test site.  The fastest eartquake waves -- the compression waves or "P" waves -- move though the crust at about 6 kilometers a second, so they should have made it to Yuzhno Sakhalinsk in about 266 seconds, or around 4 minutes.  But the data for 140 GMT shows nothing above background noise.

Even closer is this data from Mudanjiang, in Heilongjiang Province, China.  It's only around 400 miles from the supposed site of the test.  ANd yet, data for the period shows... nothing.

Both sites clearly show a small tremor that happened the previous day, but the "test" is in a clear period, where it should have been very visible.

If North Korea achieved a nuclear blast, it was small, so small that it's highly unlikely.  It appears more likely that:

1. there was some blast, but with conventional explosives and far below the level that would be generated by a nuclear test.

2. the nuclear device failed, giving a "fissle" yield.  This would not be too surprsing if North Korea tried to get by with an amount of uranium too close to the minimum critical mass, or had a flaw in the construction of the device.

3. there was never any test at all.

In any case, from what I can see, there's nothing here to report.

UPDATE: The USGS is now confirming a 4.2 event, which is more in line with what would be expected from a Trinity-class device.

So, damn it, I may well be wrong.