Ack, there is a reason I have a rule about blogging before a cup of coffee. In an earlier post, I made a math mistake (actually several, including a data entry error in a spread sheet).
Anyway, here is the data on the North Korean nuclear test, with very simple yield estimates.
You’ll want to double check these — I am taking the day off.
I’d love to see what AFTAC says.
Update: The Project for the CTBT has a calculation from Martin Kalinowski:
The U.S. Geological Survey readings indicate a seismic body wave of magnitude of 4.7, which is larger as compared to the value of 4.1±0.1 in 2006. According a preliminary assessment by Martin Kalinowski of the University of Hamburg, this corresponds to an explosive yield of about 3 to 8 kilotons TNT equivalent with a most likely yield of 4 kt. In 2006. The yield of the 2006 test explosion was approximately 0.5 to 0.8 kt TNT equivalent.
Later Update: Here is Kalinowski’s fact sheet.