Magnetic Imaging of Subsurface Lineaments for Geotechnical Applications: A Case Study from the Sohag University Campus, Egypt

This study applies the ground magnetic surveying method to investigate shallow subsurface structural lineaments within the Sohag University campus at El-Kawamel for potential engineering purposes. A detailed magnetic survey was conducted over an area of approximately 0.2 square kilometers using a high-sensitivity GEM GSM-19 Overhauser magnetometer. The survey involved six systematically spaced profiles oriented in an east-west direction with 50-meter spacing, employing a zigzag acquisition pattern to ensure full coverage of the site. A total of 1,487 magnetic readings were collected under carefully controlled conditions to minimize noise. Advanced data processing techniques, including regional–residual separation, tilt derivative (TDR), first vertical derivative (FVD), total horizontal derivative of tilt derivative (THDR_TDR), horizontal gradient (HG), and source edge detection (SED), applied to identify structural features and lineaments. Depth estimation methods such as analytic signal, source parameter imaging (SPI), and 3D Euler deconvolution revealed magnetic sources at depths ranging from about 6 to 75 meters with occasional deeper sources reaching ~113 meters in localized zones. The analysis highlighted dominant N-S, E-W and NW-SE structural trends, which are consistent with regional tectonic settings. The results demonstrate the effectiveness of ground magnetic surveying as a valuable tool for preliminary geotechnical investigations prior to construction.