North Korean Nuke Not a Dud

There’s a lot of speculation that North Korea’s nuclear test this morning may have been a failure. Skeptics point to the USGS seismic data as proof that nothing happened.

Well… I think they jumped the guns a bit.

IRIS has a page up about the event, showing nearby seismic monitoring locations.

Of special note is the MDJ station, in Mudanjiang, China. It pretty clearly shows two significant events in rapid succession, which rapidly fall off into a return to the baseline, background noise. This is far more indicative of an underground nuclear test than an earthquake.

What’s really noteworthy is the two events are most discernable on the “BH” channel – twenty to forty hertz, and barely discernable on the “LH” channel – around one hertz. Why is this noteworthy?

Higher-frequency sounds are attenuated more as they travel thru the earth. Put another way, lower-frequency waves travel thru the earth better than higher-frequency ones. SIGNIFICANTLY better.

An earthquake produces a lot of very, very low frequency energy, which travels thru the earth a considerable ways.

A small nuclear weapon, on the other hand, produces a lot less energy than an earthquake, and it seems entirely reasonable to suppose that the majority of it’s audibly-transmissible energy is going to be at relatively high frequencies.

I believe the MDJ station recorded the double event (detonation and cavity collapse) of a North Korean underground nuclear test, and the energy transmitted into the earth was predominantly well above one hertz. I believe that MDJ, in close proximity to the event, was the only station able to record the seismic signature of the event above the local background noise, because such seismic transmissions were too heavily attenuated by the time they reached stations in Japan and South Korea. I believe that, had it been a real earthquake, as has been postulated, this would not be the case.

I also suspect that the reduced transmission of seismic energy from the test may be leading experts to underestimate the size and yield of the device tested… but that’s just me.

Thoughts, anyone?

Published in: Geekiness, General, History | on October 9th, 2006| Comments Off on North Korean Nuke Not a Dud

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