Gpr And Subsurface Targets

The applications of GPR to delineate subsurface targets are currently enormously growing<br>up in Egypt. Three cases are discussed where GPR-surveys, with different central frequency<br>antennas, resulted in detecting buried man-made targets. These targets possess different<br>dimensions, buried in different host mediums, located at different depth levels, and are made of<br>different materials.<br>In the first case, a test site located near Cairo is prepared to test the efficiency and<br>resolution of GPR-technique to detect buried anti-tanks (AT) and anti-personnel (AP) inactive<br>landmines. Four GPR-traverses are performed using 500 and 1000 MHz antennas. Generally,<br>GPR-results are very encouraging with respect to the detection of the steel anti-tank mines. Antipersonnel<br>plastic mine could only be detected in the processed 1 GHz radar data. Locations of<br>reworked soils are also noted from GPR-results.<br>In the second case, GPR-survey with center frequency of 400 MHz, is essentially<br>performed to outline subsurface voids at a site located in Luxor city, about 650 km south of<br>Cairo. Analyses of the obtained GPR-data reveal no indications for subsurface voids.<br>Unexpectedly, a number of ancient concrete pillars are detected buried in the silty clay soil. The<br>pillars are extending vertically in the subsurface to more than 4m deep.<br>In the third case, GPR-surveys operating with 200 and 500 MHz center frequencies are<br>performed at an archaeological site located west of Alexandria, Egypt. The 500 MHz survey<br>succeeded to map the irregular topography of the calcareous sand bedrock. Remarkable columnar<br>GPR-signatures are observed and could be related to columns, believed to be marble columns of<br>Roman age, buried at a depth of 3.5m. A large hyperbolic GPR-anomalies are observed at 4.0m<br>deep and related to buried tombs of the same age.