Space Satellites Reveal Details Of North Korea’s 2017 Nuclear Test

North Korea’s 2017 nuclear test at Mount Mantap was ten times more powerful than the historic explosion at Hiroshima, researchers say.

AsianScientist (Jun. 11, 2018) – Scientists from Singapore, Germany, the US and China have combined satellite radar imagery and traditional seismic data to visualize land surface deformation caused by an underground nuclear explosion in North Korea. Their study was published in Science.

On September 3, 2017, two seismic events were detected at the Punggye-ri nuclear test site located on the southern side of Mount Mantap, North Korea. These events were later found to be caused by a two-stage nuclear test conducted by North Korea. Mount Mantap has also served as the site for five other North Korean nuclear tests since 2006.

To better understand the deformation of Mount Mantap following the explosion, a team of geophysicists led by Dr. Wang Teng, a senior research fellow from the Earth Observatory of Singapore (EOS) at Nanyang Technological University, Singapore, analyzed both satellite radar images as well as seismic waveforms (energy that traverses through the Earth’s layers) to accurately determine the explosion’s magnitude.

The researchers observed that the top of the mountain had experienced a rise, collapse and compaction after the detonation, which moved the mountain outwards by as far as 3.5 meters and upwards by half a meter.

“The explosive yield from the nuclear detonation with seismic and geodetic modeling was between 120–304 kilotons of TNT, which is about ten times the power of the Hiroshima bombing (~15 kilotons),” Wang explained.

Wang also noted that the spaceborne technology called synthetic aperture radar (SAR)—primarily used for monitoring earthquakes, volcanic eruptions and landslides—is a powerful tool for mapping the Earth’s surface movements.

“Unlike optical sensors, SAR transmits electromagnetic waves and records the signal reflected back from the Earth,” Wang told Asian Scientist Magazine.

“The amplitude component of the echo represents the reflectivity characteristics of [surface objects], while the phase component records the two-way traveling time, allowing the measurement of millimeter-level surface displacement. As SAR is not affected by sun illumination or clouds, it serves as one of the most important space-borne sensors for routinely observing the Earth.”

While previous investigations on underground nuclear test sites only included analyses of seismic waveforms, the incorporation of satellite imagery has allowed for the modeling of such movements in three-dimensions, as presented in this study. The researchers were also able to obtain higher resolution images without having to physically survey the site.

Moving forward, Wang said that he and his team will continue to work on the modeling of these datasets. They also seek to improve on the methods used for geodetic—relating to the geometric shape of the Earth and its gravitational field—and seismic observations of our planet.

The article can be found at: Wang et al. (2018) The Rise, Collapse, and Compaction of Mt. Mantap From the 3 September 2017 North Korean Nuclear Test.


Source: Nanyang Technological University. Photo: Google Earth/UC Berkeley.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

Lim Zeng Hao completed a degree in biological sciences at Nanyang Technological University, Singapore. In his spare time, he dabbles in new languages and daydreams about the eventual publication of his epic fantasy book series. Zeng Hao is a science writer with Asian Scientist Magazine.

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