Thread by @ArmsControlWonk

No, North Korea’s nuclear test mountain did not collapse. (A note in place of the short thread I will write after I drop my children at school.)

Ok, bottom-line up front: The reporting has been mostly hot garbage -- except the @JNBPage story. The mountain did not collapse and there is no evidence that it is unusable. I checked an image from @planetlabs dated April 25. The mountain is still there. 😀 1/8

We know the 9/2017 nuclear test really shook the mountain -- we worked with @Airbus to analyze Synthetic Aperture Radar (SAR) images to determine that it subsided. I imagine the aftershocks displaced more rock. 2/8
armscontrolwonk.com/archive/120385…

Now there are two studies, both by groups of respected seismologists. One finds that one of the "aftershocks" was in fact the collapse of the cavity created by the explosion. @JNBPage -- again, who wrote the only non-garbage story so far -- quotes the key bit. 3/8

This does not mean the tunnel complex below the mountain is ruined. North Korea shouldn't use the exact same cavity again, which has some implications for decoupling scenarios, but new branches off the main tunnel should be fine. Kim can keep testing there if he wants. 4/8

Also, let's not overstate how much the risk of containment failure might constrain Kim. Countries used to conduct atmospheric nuclear tests -- and the DPRK has threatened to do so itself. If a containment failure occurs, it's not the end of the world. 5/8
ctbto.org/specials/testi…

And don't forget -- North Korea has other tunnels into other mountains at the test site. Thanks to our friends at @planetlabs, we see continued tunneling into the west mountain as late as mid-April. No one thinks those mountains are compromised or unusable. 6/8

To sum up. Nuclear explosions make cavities. One of those cavities collapsed, which seismologists detected. Science is cool. But a cavity collapse does not mean the tunnel complex collapsed, let alone the whole mountain. 7/8

And it certainly doesn't mean the other tunnels in the other mountains are unusable. At most, North Korea might shift big tests to neighboring mountains. Kim has agreed to stop nuclear testing because of the summit(s), not because his nuclear test mountain collapsed. 8/8