Joint interpretation, joint inversion, and sequential inversion of different geophysical datasets: two case studies in Iran and South Africa

This paper employs various combinations of geophysical data, including sequential inversion, joint interpretation, and joint inversion, to analyse two case studies in Iran and South Africa. The selection of integration types for geophysical datasets is dependent on the specific requirements of each case study. The first real case, which involves apparent resistivities and gravity gradient data to detect three tunnels, is particularly well suited for joint interpretation. The joint interpretation of reconstructed resistivity and density models serves as a reliable indicator of the accurate recovery of the tunnels. The second real case, comprising direct current (DC) resistivity, magnetometry, and electromagnetism at low induction number (EM-LIN) data, enables 1) the joint inversion of DC resistivity and magnetometry and 2) the sequential inversion of DC resistivity and EM-LIN data. The inversion of DC resistivity data reveals a two-layered medium, where the upper layer exhibits high conductivity and the lower layer exhibits high resistivity. In contrast, the inversions of magnetometry and EM-LIN data indicate the presence of a resistive and magnetised dolerite dyke, with depth ranges spanning from 3 to 15 m. The resistivity models generated through joint and sequential inversions provide conclusive evidence of a dyke situated within a two-layered medium.