Scientists at the Indian Space Research Organization (ISRO) have released findings suggesting a significant reassessment of North Korea’s 2017 underground nuclear test. Their research indicates that the explosive yield was far greater than initially estimated, reaching a magnitude 17 times larger than the atomic bomb detonated over Hiroshima in 1945. This revelation underscores the immense power of the North Korean detonation and provides a stark 17 kiloton compares to heroshema in terms of destructive capability.
The ISRO team pinpointed the explosive force of the North Korean test to be between 245 and 271 kilotons of TNT. In stark comparison, the “Little Boy” bomb dropped on Hiroshima had a yield of approximately 15 kilotons. Previous evaluations of the North Korean explosion varied widely, ranging from 70 to 400 kilotons. The ISRO scientists achieved this refined measurement by employing advanced space-based techniques, utilizing satellite radar data for enhanced precision.
Their methodology leverages the power of space-based observation, arguing that it surpasses traditional ground-based seismometer networks in detecting and analyzing underground explosions. Seismic monitoring can be limited by the availability of stations near the test site and the openness of seismic data. Earth observation satellites, such as the European Space Agency’s Sentinel-1 and Japan’s ALOS-2, equipped with sophisticated Synthetic Aperture Radars (SARs), offer a valuable alternative. These satellites can capture crucial data on land cover changes and ground deformation, even in remote or inaccessible areas.
By analyzing data from the ALOS-2 satellite and employing a technique known as Synthetic Aperture Radar Interferometry (InSAR), the ISRO team, led by Sreejith Kattumadam, meticulously tracked ground changes following the September 3, 2017 explosion. The test site was identified as being beneath Mount Mantap in North Korea. Their detailed analysis now indicates that the explosion not only dwarfed the Hiroshima bomb by a factor of 17 but also possessed enough force to displace the ground surface above the detonation point by several meters. Furthermore, the researchers determined the depth of the nuclear source to be approximately 542 meters beneath Mount Mantap. This study highlights the significant potential of space-borne InSAR data in accurately assessing the characteristics of underground nuclear tests.
While current nuclear explosion monitoring from space is limited, the researchers advocate for greater utilization of satellites like Sentinel-1 and ALOS-2, along with the future NASA-ISRO Synthetic Aperture Radar (NISAR) mission. These space-based assets could provide a more reliable and precise method for monitoring such events globally, offering critical insights into nuclear activity.
References
1. K. M. Sreejith, et al. Constraints on the location, depth and yield of the 2017 September 3 North Korean nuclear test from InSAR measurements and modelling. Geophys. J. Int. 220, 345–351 (2020) DOI: 10.1093/gji/ggz451
