Optimizing Electrical Resistivity Tomography Acquisition Strategies in Rock Glacier Environments

Electrical Resistivity Tomography (ERT) is a widely used geophysical method for investigating permafrost in challenging mountain environments, such as rock glaciers (Hauck and Kneisel, 2008). This study focuses on optimizing ERT acquisition strategies using modern high-quality multi-channel georesistivity meters, steel-net electrodes, and appropriate acquisition schemes, in order to efficiently and rapidly acquire multiple ERT transects and reliably characterize the internal structure of rock glaciers, despite complex surface conditions.

As recently proposed by Pavoni et al. (2025), the use of light steel-net electrodes facilitates the deployment and removal of ERT transects in blocky terrain, ensuring optimal galvanic contact without compromising data quality. In addition to these practical benefits, the choice of acquisition scheme strongly influences survey efficiency and data reliability. Hybrid acquisition schemes based on Dipole-dipole and Multigradient multi-skip approaches, when combined with multi-channel instruments, allow for rapid data acquisition, improved model sensitivity, and enhanced evaluation of dataset quality.

In this work, we compare the performance of a mixed Dipole-dipole and Multigradient multi-skip scheme with the traditional Wenner-alpha configuration. While traditional Wenner-alpha measurements are usually acquired only in the direct configuration, the Dipole-dipole and Multigradient schemes enables the acquisition of a substantially larger number of quadripoles within the same time frame, including both direct and reciprocal measurements, which provide a more robust estimation of data error by accounting for both instrumental and systematic contributions (Binley et al., 1995).

Furthermore, we evaluate the Polo-Dipole configuration’s potential to increase model sensitivity at depth (White et al., 2003), facilitating a more reliable identification of the bottom of the frozen layer within rock glaciers. Measurements were collected in both direct and reciprocal geometries, with the remote electrode deployed at two different positions and two different distances on opposite sides of the transect. Testing these alternative positions and distances of the remote electrode provided an additional way to assess data quality, confirming the robustness of the Polo-Dipole setup and its ability to increase investigation depth without significantly affecting acquisition time.

Overall, the integration of high-quality multi-channel instruments, light steel-net electrodes, and optimized acquisition strategies enhances model sensitivity and data-quality assessment while improving operational efficiency. This approach enables the rapid acquisition of multiple transects within a single field campaign and supports the development of quasi-3D resistivity models of rock glacier structures.

References

Binley, A., Ramirez, A., & Daily, W. (1995, April). Regularised image reconstruction of noisy electrical resistance tomography data. In Proceedings of the 4th Workshop of the European Concerted Action on Process Tomography, Bergen, Norway (pp. 6-8).

Hauck, C., and Kneisel, C.: Applied Geophysics in Periglacial Environments, Cambridge University Press., 2008.

Pavoni, M., Peruzzo, L., Boaga, J., Carrera, A., Barone, I., & Bast, A. (2025). Brief communication: Use of lightweight and low-cost steel net electrodes for electrical resistivity tomography (ERT) surveys performed on coarse-blocky surface environments. The Cryosphere, 19(10), 4141-4148.

White, R. M. S., Collins, S., & Loke, M. H. (2003). Resistivity and IP arrays, optimised for data collection and inversion. ASEG Extended Abstracts, 2003(2), 1-4.