<p>The Fukushima Daiichi Nuclear Power Plant, Japan, underwent a series of sequential meltdowns in 2011 related to the magnitude 9.0 earthquake and tsunami of the same year - causing the world’s second ‘Level 7’ nuclear event after Chernobyl. Japan and the Tokyo Electrical Power Company (TEPCO) have been proactive in taking steps towards decommissioning the now hazardous site, with a clean-up timeline continuing work for another 30-40 years. However, this creates a need for long-term monitoring strategies that mitigate radiation hazards for the personnel involved with the decommissioning. Remote sensing can fill this emerging need, more specifically with Interferometric Synthetic Aperture Radar (InSAR).</p><p>InSAR can monitor ground and structure stability with millimetre scale accuracy, as well as create a historical baseline for past movement using data from ESA’s Sentinel-1 satellite mission. Here we show the applicability of InSAR monitoring across the Fukushima plant using Sentinel-1 data spanning October 2015 to October 2019. Our results clearly show an uplift signal of ~75 mm around the reactor, during the time period directly coinciding with the implementation of a perimeter ice wall which was constructed to mitigate groundwater leeching.</p><p>This study demonstrates the benefits of InSAR to monitor ground stability in near-real time, and across a wide area, without the need for direct interaction with such a hazardous site. Via this study, we have demonstrated that InSAR is a powerful technique for monitoring potential ground stability issues at highly hazardous sites, with applications for the engineering, oil and gas, and mining sectors.</p>

<p>Recent mining disasters, such as the collapse of the Brumadinho tailings dam in Brazil, have placed intense pressure on mining companies to effectively monitor their active and historical assets. Particular focus has been placed on none-profit generating aspects of mines, specifically tailings storage facilities (TSFs). These may be poorly monitored, not routinely maintained, and of unknown construction. Remote sensing techniques present an attractive option for monitoring such facilities, reducing the need for the deployment of expensive ground monitoring systems and personnel.</p><p>Here we demonstrate how satellite InSAR can be used as an effective remote monitoring solution for both active and inactive TSFs. InSAR is a powerful tool for mining companies, allowing for both frequent ongoing monitoring and, somewhat uniquely, the ability to look at historical deformation and perform post-event analysis. Furthermore, the increasing availability of satellite data, both commercial and open-access, means that regular monitoring programs are increasingly feasible and economically viable.</p><p>The application of InSAR across a mine is by no means without challenges. Active sites typically suffer from poor coherence due to mine activities, while closed sites can be heavily vegetated which further impacts coherence. Despite these challenges, InSAR can be a highly effective component of a mine monitoring program, particularly when integrated with ground based systems.</p>

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