Rock mass characterization around Saskatchewan potash mine openings using geophysical techniques: a review

Abstract

Saskatchewan potash deposits are found in relatively uniform, flat-bedded strata with few irregularities. Potash mines are highly automated and efficient, taking advantage of the uniform strata. However, anomalous geological conditions can lead to severe problems, especially with water inflows. One mine has been lost to flooding, and other mines now have or previously had large inflows of water. Geophysical techniques, especially the method of vertical seismic reflection from the surface, are used to predict anomalous geological conditions. Seismic, electric, and other geophysical methods are also used underground, sometimes in boreholes, to detect conditions around the mine openings such as the thickness of the salt cover over the mine, fractures around the opening, shale beds, the presence of water, and other rock properties. The mines generate seismic activity ranging from magnitude 3.7 earthquakes to tiny micro-earthquakes, and various field monitoring and laboratory testing programs have analyzed these. To avoid hazards discovered by geophysical methods, mine managers have often changed their plan of operation or even deleted large ore reserves. Key words : geophysics, potash mining, seismic, earthquakes.