As always when the DPRK tests, I’m in a seminar somewhere else. This time, I was discussing FMCT verification with the good people of SIPRI and the diplomats of the Conference on Disarmament.
The plot is based on the Mb to yield estimates for dry-rock, close coupled, underground nuclear explosions. I’ve used the USGS estimate for the yield calculation. The graph can only be used as a general indication because the exact geological conditions of the area is not known. It is known to have a shallow water table, which could explain why the Russians always get their yield calculations on the high end. We also don’t know how well this test was coupled to the rock.
However, as indicated, today’s North Korean test seems to be significantly bigger than its previous test. What is also interesting is that the centre of today’s test, according to the USGS, is about 5.5 kilometers away from the old test site. The IMS puts the test closer to the first site, but within the USGS margin of error. The USGS sets the error to +/- 3.8 kilometers, which strongly suggest that we’re looking at a second test site in close proximity to the first.
Interestingly, a couple of years ago I learned that the South Koreans were looking for test site preparations on the “northern side of the mountain” relative from the first site. This, to me, means that the second site has been known to the South for some time.
I’m now off to have some dinner.