Spaceborne SAR based assessment of nuclear test effects: the case of North Korea

This study aims at estimating the Earth surface deformations due to the nuclear tests carried out by Democratic Peoples Republic of Korea from the 3
^rd
of September 2017 by processing a time series of synthetic aperture radar images acquired by the COSMO-SkyMed satellite constellation. For active satellite sensors working in the X-band, phase information can be unreliable if scenarios with dense vegetation are observed. This uncertainty makes difficult to correctly estimate both the interferometric fringes and the phase delay generated by the variation in the space-time domain of the atmospheric parameters. To this end, in our research we apply the Sub-Pixel Offset Tracking technique, so that the displacement information is extrapolated during the coregistration process. Our results demonstrate the capability of spaceborne remote sensing to help characterize large underground nuclear tests in revealing an accurate estimate of the spatial displacement due to the explosions. The work also reveals the presence of a possible underground tunnel network.