Determination of Subsurface Electrical Structures in Southern Sabalan Using Two-Dimensional Inversion of Magnetotelluric Data with the Adaptive Finite Element Method

Document Type : Research - Paper

Authors

1 Ph.D, Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran

2 Professor, Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran

3 Associate Professor, Faculty of Mining, Petroleum and Geophysics, Shahrood University of Technology, Shahrood, Iran

4 Assistant Professor, Faculty of Engineering, University of Mohaghegh Ardabili, Ardabil, Iran

5 Ph.D, Renewable Energy and Energy Efficiency Organization, Tehran, Iran

Abstract

The presence of numerous hot springs in the Sabalan region makes it a highly favorable area for geothermal exploration. In this study, magnetotelluric (MT) data were used to investigate the thermal origin of geothermal resources in the southern part of the Sabalan volcanic region. For this purpose, data from 13 MT stations along a survey line with varying station spacing were employed. Since magma exhibits lower electrical resistivity compared to the surrounding host rocks, it can be detected through the magnetotelluric method. Dimensionality analysis revealed shallow-to-medium-depth structures dominated by one-dimensional (1D) and two-dimensional (2D) geometries, while deeper structures exhibited three-dimensional (3D) complexity. A 2D isotropic inversion was performed using an adaptive finite element method, incorporating rapid Occam inversion to minimize the objective function. Sensitivity analysis was conducted to evaluate the reliability of the conductive structures resolved in the final model, confirming high accuracy and robustness. The model resulting from 2D inversion of the MT data demonstrates that one of the thermal sources of the geothermal system originates from the southern part of the Sabalan region. Furthermore, the migration of high-temperature fluids is controlled by fault-induced fractures in the southern part of the region, directing the fluids toward the northwest.

Keywords

Main Subjects

References

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History

  • Receive Date: 17 October 2024
  • Revise Date: 22 September 2025
  • Accept Date: 17 June 2025

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