ALTERNATIVES TO GROUND PENETRATING RADAR FOR THE DETECTION OF CLANDESTINE GRAVES

The ability to detect mass graves in war-torn regions and find victims of homicide has become increasingly important. Subsurface detection of clandestine graves is often difficult in regions with high erosion or other factors limiting the amount of surficial evidence. Ground-Penetrating Radar (GPR) has repeatedly been proven to be an effective near-surface geophysical technique in the such for subsurface graves when followed by archeological excavation. GPR falls short after the cadaver tissues fully decompose due to a lack of surface area to generate a reflection response. Even without tissue left to cause a reflection, other near-surface geophysical techniques can detect changes in the properties of the soils due to the chemical and physical remnants of the cadaver and its grave. Such techniques include magnetometry, electromagnetic induction (EMI), resistivity and thermal imaging. To test the practicality of these methods four 80 cm deep graves were created. A pig cadaver was placed in each grave. Two of the cadavers were clothed and had metallic objects, such as a cell phone and rings, placed on them. Periodic surveys using all techniques, including GPR, were conducted. Additionally, a 3-dementional model of the graves was constructed using photogrammetry. While GPR still proved effective, other techniques detected the graves as well. The most effective new technique found was resistivity as the pigs proved to be a highly resistivity anomaly, particularly two weeks after burial. These additional near-surface geophysical techniques could be used to detect clandestine graves when GPR is fails to do so.