Archeological exploration via integrated shallow geophysical methods: case study from Saqqara, Giza, Egypt

Abstract An integrated geophysical survey, Seismic Refraction Tomography (SRT), Ground Penetrating Radar (GPR), and Electrical Resistivity Tomography (ERT), was carried out at the UNESCO World Heritage site of Saqqara, Giza, Egypt, as part of the Cairo University’s ongoing exploration project (Phase II). The primary objective of this survey was to detect and map any subsurface archeological features, such as tombs, within the study area. These geophysical methods were selected for their rapid, non-invasive nature, offering a cost-effective alternative to conventional excavation and trenching techniques. By providing valuable insights into the subsurface without disturbing the integrity of the site, the survey contributes significantly to archeological research. Each geophysical method provides unique insights: SRT data distinguished a shallow sandstone layer P-wave velocity (Vp = 400–1100 m/s) above a deeper limestone bedrock (Vp: 1200–1900 m/s), with low-velocity anomalies suggesting potential voids or chambers. GPR profiles detected linear features, likely walls or paths, alongside amplitude anomalies and low-amplitude anomalies suggesting chambers or rooms filled with high-conductive materials like clays and mud bricks. ERT data revealed high-resistivity limestone zones and low-resistivity anomalies suggestive of filled with conductive materials like clays or mud bricks. The integrated approach identified three prominent anomalies A-1, A-2, and A-3 with consistent signatures across datasets: A-1 as a probable room filled with conductive material; A-2, a low-resistivity, low-velocity hall surrounded by sediments; and A-3, a subsurface chamber all of them at approximate depth 2 m. Combined 3D visualization of P-wave velocity and resistivity further reinforce these interpretations, validating the efficacy of integrated geophysical surveys in non-invasively mapping buried archeological features at Saqqara. The study emphasizes the importance of combining multiple geophysical methods for archeological exploration, providing a robust framework for future investigations at the study area and other historically significant sites. Moreover, the research supports ongoing preservation efforts, highlighting the role of advanced geophysical techniques in uncovering the hidden legacies of ancient civilizations while ensuring the protection of these cultural treasures.