Comparison of Time-lapse GPR and Resistivity over Simulated Clandestine Graves

Abstract

SummaryForensic geophysics should be an invaluable tool to assist search teams to detect and locate clandestine graves of buried murder victims. At present however, geophysics is underutilised and currently used techniques may not be optimal for specific targets or sites. There is a need for geophysical datasets to be collected over known burial sites for varying time periods post-burial.A study site was created with a naked and wrapped pig cadaver. The dimensions are based on available statistics of discovered burials. Monthly surveys using resistivity, Electrical Resistivity Tomography (ERT) and Ground Penetrating Radar (GPR) were performed postburial. Resistivity results show low anomalies over the naked pig and a smaller high anomaly over the wrapped pig with respect to background values. ERT time-lapse data shows optimum survey periods for the naked and wrapped pigs to be 9 and 3 months respectively. GPR 2D profiles detected both burials, with the wrapped pig exhibiting stronger reflection events. Lower frequency (110 MHz) antennae were found to be the optimal frequency to detect pig burials. Main Objectives:1. Detail time-lapse geophysical results over simulated clandestine graves.2. Determine optimal method(s) to locate a grave post-burial and if this changes over time.3. Determine which frequency GPR antennae is optimal.4. Compare GPR with ERT surveys.

Electrical resistivity survey to search for a recent clandestine burial of a homicide victim, UK

“…Therefore, we suggest that the best use of resistivity surveys is to narrow down rough target area(s), before higher resolution geophysical surveys (eg GPR or Electrical Resistivity Imaging, see [37]), or searches using physical probes or trained victim recovery dogs, or conventional excavations over these area are undertaken.…”

Case history: integrated geophysical survey at Katarínka Monastery (Slovakia)

“…Using this shape as the basis for an interpretation, the object might have served as a water or food storage pit or well. Different works dealt with a combined interpretation and inversion of GPR and ERT (e.g., Pringle, Jervis, and Tuckwell and Doetsch et al ), all leading to better resolved and interpretable results, providing a wider basis of physical properties. The result presented here follows these examples, also showing a good correlation between ERT and GPR and showing how well ERT and GPR complement each other and making it possible to assess more physical parameters for interpretation.…”