EAGE Student Webinar on Ground Penetrating Radar (GPR) in Applied Geophysics: Principles, Applications and New trends by Dr. Hesham El-Kaliouby

Student Webinar by Dr. Hesham El-Kaliouby

GPR is quick, easy and relatively inexpensive to run, and measured data have high vertical and horizontal resolutions. GPR could be used for many applications including geotechnical and engineering as it could provide early warning for civil engineers to take proper precautions before any catastrophic situation arise. GPR could also be used for identifying cavities within sedimentary rock. GPR uses high frequency electromagnetic waves to map different lithologies or subsurface objects that have different electrical properties. As the GPR systems is commonly towed along a surface using a wheel cart, the transmitter antenna sends pulses of high frequency electromagnetic energy to penetrate into the subsurface, a fraction of the GPR waves is reflected back to the surface when it encounters an interface, where there is a contrast in dielectric permittivity of subsurface materials. Subsurface structures are detected by measuring the amplitude and two-way travel time of this reflected energy to the receiver antenna. Dry limestone is a favorable media to the penetration of GPR signals and the karstic cavities, which give strong radar reflections due to the contrast in electrical permittivity between the air-gap and the surrounding host rock. GPR could be measured in different configurations including common-offset, common midpoint and as radar tomography between boreholes. GPR could be used for many other applications including geological and hydrogeological investigations (e.g. mapping of bedrock topography, groundwater levels, glacial structures, and landslide), Environmental Studies (e.g. groundwater pollution, salt water intrusion, hydrocarbon leakage, landmines, unexploded ordnance (UXO), and landfills); engineering and geotechnical investigations (e.g. constructions, foundations, tunnels, utilities, dams, pavements, road beds, railway embankments, piles, bridge decks, underground storage tanks, and reinforcing bars). GPR is considered as one of the best tools for detection of cavities, tombs, and archaeological targets. GPR could also be used for forensic investigations. The GPR depth of investigation increases with low frequency antenna, high transmitter power and high receiver sensitivity. However, the depth of penetration decreases with high electrically conductive materials like clays and saline water or highly conductive contaminants. In general, GPR is an efficient technique for the identification and characterization of shallow subsurface structures. GPR results not only inform us about existing structures, but also warns of potentially hazardous situation like sinkholes and landslides. This webinar will provide background about the principles, applications, suitability and limitations of the GPR method for investigating the subsurface and new trends in GPR equipment and field measurements. Keywords: GPR, Ground Penetrating Radar, principles, applications, new trends.