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Resistivity and Induced Polarization (ERT/IP) Survey for Bedrock Mapping in Permafrost, Svalbard
- Publisher: European Association of Geoscientists & Engineers
- Source: Conference Proceedings, 25th European Meeting of Environmental and Engineering Geophysics, Sep 2019, Volume 2019, p.1 - 5
Abstract
Permafrost demands for special requirements when designing infrastructure and for this, it often needs to be characterized in details. Ground-based Electrical Resistivity Tomography (ERT) provides an indirect near-surface indication of permafrost down to a few tens of meters depth, when carefully calibrated by boreholes. While ERT is very successful for mapping the active layer (i.e., the layer which thaws and refreezes annually), further interpretation of resistivity profiles is impeded by the lack of resistivity contrast within the permafrost. Indeed, the lithological structures are hidden by the strong resistivity of the frozen layer. We present an example combining ERT with Induced Polarization (IP) surveying which allows to uncover the interface between the sediments and the bedrock. Although IP is rarely acquired on permafrost, the present case study shows the benefit of measuring it simultaneous to the ERT survey, at no extra costs or time consumption. The study is located near the cities of Longyearbyen and Barentsburg, on the island of Spitsbergen, Svalbard. Eight profiles were carried out in September 2018, when expected active layer thicknesses were at their maxima. Two-dimensional inversion was performed with the commercial software RES2DINV for the resistivity data and Ahrusinv for the chargeability data.