Interferometric Synthetic Aperture Radar (InSAR)-based measurements of displacements due to geomorphologic changes in northern mining environments – testing and validating InSAR in open pit and tailings of Pyhäsalmi Mine, Finland

Abstract

Monitoring the stability of mine structures, such as tailing ponds and open-pits, is crucial for ensuring the safety of personnel on-site and for preventing environmental accidents. This must be done, not only during the active operation of a mine, but also during possible reuse phases, and even after closure. Currently, monitoring the structural stability of the mining area relies heavily on manually conducted RTK-GNSS-based measurements of established control points. While this is a precise and relatively simple technique, it does pose a limit to how many control points can feasibly be monitored, as using tens or even hundreds of control points is time-intensive and laborious. Consequently, monitoring larger areas and areas requiring frequent measuring can be challenging. A remote monitoring option would also remove the element of danger that comes from having to reach control points in possibly unstable areas. InSAR appears to be an alternative for measuring terrain displacements in large, mining areas. Some limitations remain, as terrain coverage and weather conditions in northern latitudes can hinder InSAR analysis.  The Callio Lab research centre at the Pyhäsalmi mine in Finland has been chosen as a test site for InSAR measurements conducted during the EU H2020-funded GoldenEye project. InSAR is used to measure terrain displacement as a result of geomorphologic changes during the summer and autumn of 2022. Additionally, InSAR analysis will be carried out using a network of corner reflectors during winter 2023. InSAR measurements will be evaluated and compared to drone imagery-based photogrammetric Digital Elevation Models (DEM) and field observations. Supplementary RTK-GNSS measurements are planned to be used to control the stability of selected control points. Results will provide valuable insight about InSAR usability for long-term monitoring in northern latitudes in mine environments, as well as, knowledge related to weather and terrain conditions required for obtaining reliable InSAR. Results will also touch on the main challenges faced when using InSAR in such an environment. This work has been supported by project Earth observation and Earth GNSS data acquisition and processing platform for safe, sustainable and cost-efficient mining operations (Goldeneye) ID: 869398, Horizon 2020.