Jeffrey LewisDPRK Nuclear Tests

Jack Murphy and several colleagues at SAIC have released a very interesting paper that uses a variety of geospatial and seismic data to locate the 2006 and 2009 nuclear explosions conducted by the DPRK, as well as estimate the yield and depth of burial.  (Murphy et al, Exploitation of the IMS and Other Data For a Comprehensive, Advanced Analysis of the North Korean Nuclear Tests. You can also click on the image for the poster.)

Murphy et al conclude that the best fit is a pair of tests with yields of 0.9 kilotons at 200 meters (2006) and 4.6 kilotons at 550 meters (2009).

Murphy or one of the alii had a very clever idea — use the ratio of certain seismic data from tests in 2006 and 2009 to infer the yield and depth of burial for each event having determined the relative location of the two events as well as some other parameters.  (Ok, it is a little more complicated than that — Murphy has been one of the developers of a method for using network averaged teleseismic P wave spectra in place of traditional Mb and Ms measurements.  If you want to better understand the method, I would probably start with Murphy and Barker, Network-averaged teleseismic P-wave spectra for underground explosions, 1989. To be honest, I find this stuff pretty challenging even when I have the time to read slowly.)


  1. Michael (History)

    4.6 kilotons? Iam really impressed… That means the tested device was an success for the North Korean weapon engineers? Sounds interesting!


  2. Michael (History)

    Me again… The estimated yield of 4.6 kt overpowered me. I think we should do a few validations concerning the P wave yield. Maybe it doesnt meet the geological circumstances in detail. I think the estimated yield of the device is (even with boosting) to high. That is just a rough guess, I dont have a clue about die exact geological situation at the nuclear test site.


    • Jeffrey (History)

      The high yield is a function of the depth of burial. That’s what makes the paper so interesting, especially relative to US announcements of a “few kilotons” yield. Usually a “few” means 1, 2 or 3. Rarely does it mean 4 or 5.

    • yousaf (History)

      I believe the ~4kT value has been tossed around for some time — even right after the 2009 test.


      “According to early reports, Monday’s North Korea event certainly seems like a deliberate explosion in the right place. However, it was too small to be a successful Hiroshima-class crude explosive device, by a factor of three or four. The reported estimates of Richter magnitude spread from 4.5-5, and the standard conversions to explosive yield suggest a yield of 2-6 kiloton-equivalents of TNT. Most of the latest Richter magnitude estimates have come in the low half of the 4.5-5 range, so it seems likely that the yield was 4 kilotons or smaller.”

    • yousaf (History)
    • Jeffrey (History)

      Yes, I recall. The Washington Times wrote up the estimates (“Estimates of size of Pyongyang’s nuclear test vary“) being floated by US officials in 2009.

  3. bradley laing (History)

    One of the worst accidents during the Soviet Space Program happened because a Soviet general was running the launch site, and insisted on cutting corners. He was rewarded by having his remains indentified by the medals he wore on his uniform, after the accident was over.

    What about the idea that the first test device and the second were identicle on the drawing board, and someone insisted on cutting corners in developing the first one?

  4. bradley (History)

    It was the October 24 1960 disaster where Marshal Mitrofan Nedelin refused to delay a launch for two weeks. The death toll is estimated at 120.

  5. A Complete Stranger (History)

    I find the most interesting finding to be the depth calculation of the second detonation. It is VERY important to have a sesmic determination of this depth. We were always pretty sure it was deep (IF it was a nuclear blast) but this really helps. 550 meters probably would explain why radioisotopes were not detected in the first 24 hours but it doesnt sound deep enough to prevent them from being released over time. I hope someone publishes more information about the long-term search for radioistopes.