Using DC resistivity tomography to detect and characterize mountain permafrost

Abstract

Direct‐current (DC) resistivity tomography has been applied to different mountain permafrost regions. Despite problems with the very high resistivities of the frozen material, plausible results were obtained. Inversions with synthetic data revealed that an appropriate choice of regularization constraints was important, and that a joint analysis of several tomograms computed with different constraints was required to judge the reliability of individual features. The theoretical results were verified with three field experiments conducted in the Swiss and the Italian Alps. At the first site, near Zermatt, Switzerland, the location and the approximate lateral and vertical extent of an ice core within a moraine could be delineated. On the Murtel rock glacier, eastern Swiss Alps, a steeply dipping boundary at its frontal part was observed, and extremely high resistivities of several MΩ indicated a high ice content. The base of the rock glacier remained unresolved by the DC resistivity measurements, but it could be constrained with transient EM soundings. On another rock glacier near the Stelvio Pass, eastern Italian Alps, DC resistivity tomography allowed delineation of the rock glacier base, and the only moderately high resistivities within the rock glacier body indicated that the ice content must be lower compared with the Murtel rock glacier.

Internal Structure and Current Evolution of Very Small Debris-Covered Glacier Systems Located in Alpine Permafrost Environments

“…The inter-electrode spacing was 5 m in the largest sites (les Rognes and Tsarmine) and 4 m in Entre la Reille. Following Hauck et al (2003), salt-water saturated sponges were used to improve the electrical contact between electrodes and the porous surface material. Results were processed with Prosys II.…”

Geophysical mapping of palsa peatland permafrost

“…Ground penetrating radar (GPR) has been used extensively in permafrost studies for identifying the boundaries of permafrost (e.g., Arcone et al, 1998;Doolittle et al, 1992;Hinkel et al, 2001;Moorman et al, 2003), characterizing ground ice structures (De Pascale et al, 2008;Hinkel et al, 2001;Moorman et al, 2003), and estimating seasonal thaw depth and moisture content of the active layer (Gacitua et al, 2012;Westermann et al, 2010). Electrical resistivity tomography (ERT) has also been widely applied in permafrost studies (Hauck et al, 2003;Ishikawa et al, 2001;Kneisel et al, 2000), the majority of which focus on mountain permafrost. By combining two or more geophysical methods complementary information can often be acquired raising the confidence in interpretations of permafrost characteristics (De Pascale et al, 2008;Hauck et al, 2004;Schwamborn et al, 2002).…”

Internal structure and permafrost distribution in two alpine periglacial talus slopes, Valais, Swiss Alps

“…For this reason, the application of 2D electrical resistivity tomography (ERT) in mountain permafrost studies constitutes one of the most common geophysical methods for the prospecting of alpine periglacial landforms, such as rock glaciers, talus slopes and icecored moraines (e.g. Hauck et al, 2003;Marescot et al, 2003;Hilbich et al, 2009). ERT measurements were conducted by applying an electric current into the ground, measuring its intensity with two current electrodes and measuring the resulting difference of potential with two other electrodes.…”