A new way to detect secret nuclear tests: GPS

[bananas]

http://www.thebulletin.org/web-edition/op-eds/new-way-to-detect-secret-nuclear-tests-gps

A new way to detect secret nuclear tests: GPS
By Jihye Park, Dorota A. Grejner-Brzezinska, and Ralph von Frese | 18 August 2011

Article Highlights

• North Korea's second known nuclear bomb test was conducted deep underground and in extreme secrecy.
  
• The May 2009 explosion disturbed the ionosphere in a way that could be detected in GPS signals at 11 receivers in the region.
  
• GPS could complement other nuclear test detection methods and give the US more reason to ratify the Comprehensive Test Ban Treaty.

When North Korea conducted its second known nuclear bomb test on May 25, 2009, the country's leaders took extreme care to conceal the details of the event. They detonated the bomb a kilometer or so beneath the earth, so no radiation could escape; radiation clues could have enabled member countries of the Comprehensive Nuclear Test Ban Treaty Organization to more accurately determine the type and size of the bomb tested.

What the rest of the world knows about the bomb was learned from seismic waves. Tremors registering at 4.52 on the Richter scale confirmed that the test took place just before 1 a.m. Coordinated Universal Time near the village of P'unggye and suggested that the yield was on the order PDF of a few kilotons.

At the time, however, the May 25 bomb also sent a different signature, this one into the atmosphere. It did not release radioactive gas or dust, as would be the case for a bomb detonated on the Earth's surface. Rather, it released a shockwave -- a bubble of disturbed air that spread out from the test site across the planet and high into PDF the ionosphere.

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We calculated that within 25 minutes, the leading edge of the shockwave had traveled 225 miles to the nearest GPS station in our study, which was located in Inje County, Gangwon Province, South Korea. By the end of the first hour, the disturbance had reached all 11 stations. The shockwave propagated through the air at 9 miles per minute, or 540 miles per hour. Based on the timing of the shockwave at the different receiver locations, we were able to trace the origin of the explosion back to P'unggye, in agreement with the seismic data for the event.

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[TheWraith]

1. The Global Positioning System has long been surveying for nuclear tests.

That's the lesser known role of the GPS satellites: they have nuclear test detection capabilities. Since they're going to be blanketing the globe anyway, it kills two birds with one stone.