Seismotectonic and anthropogenic factors controlling landslide hazard in Gafsa phosphates quarries

Ground and slope instability problems resulting from open pit extractions occur in the quarrying areas as well as within the tailing or heaps of waste materials. Common instability hazards and risks associated with mining and quarrying activities originate from natural and/or anthropogenic sources. The emergence of instability issues impedes the mineral extraction because they raise concerns about the safety of personnel and machineries in and around the extraction site, affect the scheduled and development of exploitation and also increase costs in extraction operations. In-situ investigation and analysis of instability problems that occurred within the tailing and the bedrocks in the open pit phosphates quarries of Gafsa, west-central Tunisia, provided reliable informations on why and how the observed landslides initiated and aggravated and why the implemented mitigation and management process are ineffective or mostly fail. The analysis of time-series satellite images and the mapping of structures that had occurred reveled the growth of the sliding surfaces, the displacement of sliding materials and the onset and growth of associated extensional and compressional structures upstream and downstream of the landslide, respectively. However, the field observations revealed the seismotectonic and anthropogenic factors, the mechanical processes and the geotechnical conditions that contributed to the sliding. The findings ought to alert workers to implement adequate design for the quarry environment to mitigate the landslide risk and comply with safety standards and sustainable extraction.