Title: Geophysics applied to Geotechnical applications Information about the near-surface is often required for mine-related activities, such as geotechnical assessment for construction or tailings monitoring. Often, this information is acquired through laborious drilling and sampling of boreholes. The geophysical method of electromagnetics is able to provide rapid information about the electrical conductivity of the near-surface (on the scale of a few metres to 100 metres). The method is sensitive to conductivity changes in the subsurface, useful for mapping overburden/bedrock interface, soil type (such as gravel, clay or hard rock), detecting ore deposits and mapping extent and depth of tailings. In the electromagnetic (EM) method, an 8 m long cigar-shaped sensor is towed 30 m above the ground. The sensor transmits EM energy into the ground, measuring the response which is related to electrical conductivity in the subsurface. Data is processed after the survey to determine spatial extent and depth distribution of ground conductivity. Through knowledge of the different conductivity of various materials, the structure of the ground can be inferred. In this talk, we briefly introduce the theory of electromagnetics and describe the electrical conductivity of various materials. We then provide some examples of the method being used to image contamination plumes, being used in place of borehole drilling to plan a pipeline route and for mineral exploration.
