Nuclear test’s location remains unclearFollowing North Korea’s fourth nuclear test last week, South Korean experts have scrambled to come up with answers to where the detonation may have taken place and whether it was a hydrogen bomb as was claimed.
“We are analyzing through detailed data where North Korea’s fourth nuclear test took place, what size it was, and what kind of technology was employed,” a South Korean government official said.
Such analysis involves cooperation with the multiple agencies that have gathered data, including information on the seismic activity incurred from the explosion. Participating entities include the Earthquake Division in the Korean Meteorological Administration’s National Meteorological Center, the Korea Institute of Geoscience and Mineral Resources, the Korea Institute of Nuclear Safety and the Korea Atomic Energy Research Institute.
Officials have also procured clips of North Korea’s Punggye-ri nuclear test site in Kilju County, North Hamgyong Province, from before and after the nuclear test, which Pyongyang claims was a hydrogen bomb. But discrepancies remain on where the test may have been carried out.
“North Korea’s nuclear test would [have been conducted] under the highest mountain in the region,” a Defense Ministry official said Monday, meaning that it likely took place near the site’s western mineshaft.
The location, based on the National Meteorological Center’s coordinates for the epicenter of the seismic event, was determined to have taken place about two kilometers northeast of the site’s second mineshaft, the Ministry of National Defense said in a report to the National Assembly evaluating North Korea’s fourth nuclear test. The epicenter was determined to be at 41.297 degrees North latitude and 129.09 degrees East longitude. However, the map provided by the Defense Ministry showed the location to be north, rather than northeast of the mine’s second shaft, and did not explain the reason for the discrepancy in location, which was approximately 24 kilometers (15 miles) off. Military officials backtracked, saying that the KMA data was only used for reference and that their location had been based on different data. But some experts say that there is also the possibility that there is a third mineshaft.
“It’s true that the location of the nuclear test was near the second mineshaft,” an Army official said. “We are confirming the exact situation.
North Korea’s previous nuclear tests in 2009 and 2012 took place at this second mineshaft on the west side while the first shaft where the 2006 test was conducted is seen to be defunct.
Lee Chun-geun, a research fellow with the Science and Technology Policy Institute, said on the location discrepancy, “The same entrance may be used, but inside the mine, many shafts can be dug up. Since the nuclear test site is granitic, there is a relatively lesser chance that the tunnels will collapse, depending on the nuclear test.”
Relevant agencies have collected five sets of air samples from over the East Sea and analyzed them over the weekend to track down possible airborne radioactive particles that may have been released from the test.
However, the Nuclear Safety and Security Commission said Monday that it is currently impossible to determine the type of nuclear test the North conducted based on an initial analysis of air samples conducted since Friday.
Traces of radioactive xenon-133 were found in the first three samples, but the amount - no more than 0.31 millibecquerels per cubic meter of air - was in line with usual levels.
Xenon-133 was not found in the remainder. The institute said that it was difficult to determine what type of nuclear test was conducted since only xenon-133 had been found and other radioactive isotypes like xenon-131 and xenon-135 were not detected.
BY JEONG YONG-SOO, KANG KI-HEON, SARAH KIM [firstname.lastname@example.org]