Underground mining can produce subsidence phenomena, especially if orebodies are surficial or occur in soft rocks. In some countries, illegal mining is a big problem for environmental, social and economic reasons. However, when unauthorized excavation is conducted underground, it is even more dangerous because it can produce unexpected surficial collapses in areas not adequately monitored. For this reason, it is important to find quick and economic techniques able to give information about the spatial and temporal development of uncontrolled underground activities in order to improve the risk management. In this work, the differential interferometric synthetic aperture radar (DInSAR) technique, implemented in the SUBSOFT software, has been used to study terrain deformation related to illegal artisanal mining in Ecuador. The study area is located in Zaruma (southeast of El Oro province), a remarkable site for Ecuadorian cultural heritage where, at the beginning of the 2017, a local school collapsed, due to sinkhole phenomena that occurred around the historical center. The school, named “Inmaculada Fe y Alegria”, was located in an area where mining activity was forbidden. For this study, the surface deformations that occurred in the Zaruma area from 2015 to 2019 were detected by using the Sentinel-1 data derived from the Europe Space Agency of the Copernicus Program. Deformations of the order of five centimeters were revealed both in correspondence of known exploitation tunnels, but also in areas where the presence of tunnels had not been verified. In conclusion, this study allowed to detect land surface movements related to underground mining activity, confirming that the DInSAR technique can be applied for monitoring mining-related subsidence.

The collapse of the tailing “Dam B1” of the Córrego do Feijão Mine (Brumadinho, Brasil) that occurred in January 2019 is considered a large socio-environmental flood-disaster where numerous people died and the local flora and fauna were seriously affected, including agricultural areas of the Paraopeba River. This study aims to map the land area affected by the flood by using multispectral satellite images. To pursue this aim, Level-2A multispectral images from the European Space Agency’s Sentinel-2 sensor were acquired before and after the tailing dam collapse in the period 2019–2021. The pre- and post-failure event analysis allowed us to evidence drastic changes in the vegetation rate, as well as in the nature of soils and surficial waters. The spectral signatures of the minerals composing the mining products allowed us to highlight the effective area covered by the flood and to investigate the evolution of land properties after the disaster. This technique opens the possibility for quickly classifying areas involved in floods, as well as obtaining significant information potentially useful for monitoring and planning the reclamation and restoration activities in similar cases worldwide, representing an additional tool for evaluating the environmental issues related to mining operations in large areas at high temporal resolution.

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Underground mining can produce subsidence, which can be coincident with mining activities or delayed in response to the time-dependent deformation of the rocks. Therefore, in these cases, it is essential to effectively monitor the soil deformations at different times during and after mining activity. In the present work, an integrated approach based on geotechnical numerical modeling and Advanced Differential Interferometric Synthetic Aperture Radar (A-DInSAR) method has been applied to detect, study and monitor the subsidence related to mining activity in the Nuraxi Figus coal district (Sardinia, Italy). Two datasets of high-resolution COSMO-Skymed images were acquired, respectively in two covering periods: from 2011 and 2014, and from 2013 to 2020. The A-DInSAR results show that the predominant displacement rates are located in correspondence with the panels. The cumulated satellite-based LoS displacements vary in the first period between − 130 and + 28 mm and − 293 and + 28.4 mm, while, during the second period between − 6.9 and + 1.6 mm and − 8.72 and + 4.33 mm in ascending and descending geometries, respectively. The geotechnical numerical model allowed to obtain a value for the maximum expected. By using the vertical and horizontal components it was possible to reconstruct the kinematics of the deformation considering three phases: pre-mining, syn-mining, and post-mining activity. The temporal evolution of displacements started during the mining extraction in 2011, achieved the major values in correspondence of post-mining operations, during the period from 2013 to 2014 and continued slowly until 2020. The near real-time monitoring system applied in this study proved to be very useful for detecting subsidence during the mining activity and the post-mining period.

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