SEOUL — New radar satellite images show the Sept. 3 nuclear test by North Korea was powerful enough to sink a roughly 85-acre area on the peak of a mountain above the tunnels where the test likely took place.
North Korea carries out its nuclear tests in a complex of tunnels at its Punggye-ri site and images of the mountains, in this case Mt. Mantap, above it can give experts a sense of where the device was tested exactly and how powerful it was.
The new Synthetic Aperture Radar satellite images, captured before and after Sept. 3, showed “significant changes at Mount Mantap’s peak elevation. Prior to the test, Mount Mantap was 2,205 meters high; the mountain has since diminished in height,” wrote Jeffrey Lewis, head of the East Asia program at the James Martin Center for Nonproliferation Studies in California.
“You can see that the explosion visibly displaces the mountain, which demonstrates both how large the explosion was but also that it occurred in the same tunnel complex as the preceding four nuclear tests,” Lewis wrote on the Arms Control Wonk website. “This is useful because the relationship between the size of the explosion and the magnitude of the seismic signals is sensitive to the overburden — how much rock is above the explosion.”
The images were taken by Airbus, a space technology company that makes earth observation satellites, using its TerraSAR-X satellite, and provided to experts at the center. You can see the change in this animated image Lewis posted on Twitter:
The device, which North Korea described as a hydrogen bomb capable of being placed on a ballistic missile, was the most powerful tested to date. Original estimates had put its yield in the 100 kiloton range, but updated seismic data analyzed by experts this week put it closer to a whopping 250 kilotons, or nearly 17 times more powerful than the bomb that flattened Hiroshima.
The new images are “additional proof that the September 2017 explosion was much larger than ever before at this site,” said Melissa Hanham, senior research associate at the Center for Nonproliferation. In comparison, radar images of last year’s nuclear test did not show a noticeable change in the surface area of the same mountain, she said.
The sunken area corresponds with some of the highest peaks of Mt. Mantap, Hanham said.