There are some interesting issues concerning verifying and measuring todays alleged nuclear test. Initial results show a blast less than 1 kiloton. This may indicate a failed test, a “fizzle,” or perhaps the North Koreans hid the true yield by insulating the shock waves from the surrounding ground somehow. I doubt the geology of the area is very well known (at least by us) and perhaps unconsolidated sediments would adsorb some of the energy of the blast. However, we should have a good handle on tests done in loose sediments. I have stood on the rim of the Sedan crater at the Nevada Test Site and I really think we understand and can model energy propagation through loose sediments and soil. Another option is that the North Koreans detonated a large amount of conventional explosives to simulate a nuclear explosion. This is possible but I don’t think it is very likely. Another possibility is that the test was a very small yielding weapon like a tactical weapon. I don’t think this is very likely either. Very low yield weapons are very technologically advanced and difficult to make.

I think they had a fizzle. No country’s first test of a plutonium device has been less than about 10 kilotons and it is well known that North Korea has enough material. India’s first plutonium bomb was quite primitive and it yielded 12 kilotons. Hopefully, some more data will come out from this test soon and we can better understand exactly what happened. I think the North Korean nuclear technology is as bad as their rocket technology.