Preprints
https://doi.org/10.5194/tc-2021-234
https://doi.org/10.5194/tc-2021-234

  21 Sep 2021

21 Sep 2021

Review status: this preprint is currently under review for the journal TC.

Spectral Induced Polarization imaging to investigate an ice-rich mountain permafrost site in Switzerland

Theresa Maierhofer1,2, Christian Hauck2, Christin Hilbich2, Andreas Kemna3, and Adrián Flores-Orozco1 Theresa Maierhofer et al.
  • 1Department of Geodesy and Geoinformation, TU-Wien, Vienna, 1040, Austria
  • 2Department of Geosciences, University of Fribourg, Fribourg, 1700, Switzerland
  • 3Department of Geosciences, University of Bonn, Bonn, 53121, Germany

Abstract. Spectral induced polarization (SIP) measurements were collected at the Lapires talus slope, a long-term permafrost monitoring site located in the Western Swiss Alps, to assess the potential of the frequency dependence (within the frequency range of 0.1–225 Hz) of the electrical polarization response of frozen rocks for an improved permafrost characterization. The aim of our investigation was to (a) find a field protocol that provides SIP imaging data sets less affected by electromagnetic coupling and easy to deploy in rough terrains, (b) cover the spatial extent of the local permafrost distribution, and (c) evaluate the potential of the spectral data to discriminate between different substrates and spatial variations in the volumetric ice content within the talus slope. To qualitatively assess data uncertainty, we analyze the misfit between normal and reciprocal (N&R) measurements collected for all profiles and frequencies. A comparison between different cable setups reveals the lowest N&R misfits for coaxial cables and the possibility to collect high-quality SIP data in the range between 0.1–75 Hz. We observe an overall smaller spatial extent of the ice-rich permafrost body compared to its assumed distribution from previous studies. Our results further suggest that SIP data help to improve the discrimination between ice-rich permafrost and unfrozen bedrock in ambiguous cases based on their characteristic spectral behavior, with ice-rich areas showing a stronger polarization towards higher frequencies in agreement with the well-known spectral response of ice.

Theresa Maierhofer et al.

Status: open (until 19 Nov 2021)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse
  • RC1: 'Comment on tc-2021-234', Jacopo Boaga, 29 Sep 2021 reply

Theresa Maierhofer et al.

Theresa Maierhofer et al.

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Short summary
We extend the application of electrical methods to characterize alpine permafrost using the so-called induced polarization (IP) effect associated with the storage of charges at the interface between liquid and solid phases. We investigate different field protocols to enhance data quality and conclude that with appropriate measurement and processing procedures, the characteristic dependence of the IP response of frozen rocks improves the assessment of thermal state and ice content in permafrost.