title: Geophysical monitoring of simulated graves with resistivity, magnetic susceptibility, conductivity and GPR in Colombia, South America.
abstract: In most Latin American countries there are significant numbers of both missing people and forced disappearances, ∼71,000 Colombia alone. Successful detection of buried human remains by forensic search teams can be difficult in varying terrain and climates. Three clandestine burials were simulated at two different depths commonly encountered in Latin America. In order to gain critical knowledge of optimum geophysical detection techniques, burials were monitored using: ground penetrating radar, magnetic susceptibility, bulk ground conductivity and electrical resistivity up to twenty-two months post-burial. Radar survey results showed good detection of modern 1/2 clothed pig cadavers throughout the survey period on 2D profiles, with the 250MHz antennae judged optimal. Both skeletonised and decapitated and burnt human remains were poorly imaged on 2D profiles with loss in signal continuity observed throughout the survey period. Horizontal radar time slices showed good anomalies observed over targets, but these decreased in amplitude over the post-burial time. These were judged due to detecting disturbed grave soil rather than just the buried targets. Magnetic susceptibility and electrical resistivity were successful at target detection in contrast to bulk ground conductivity surveys which were unsuccessful. Deeper burials were all harder to image than shallower ones. Forensic geophysical surveys should be undertaken at suspected burial sites.
authors.affiliation: Departamento de Geociencias, Universidad Nacional de Colombia y Laboratorio de Evidencia Traza, Instituto Nacional de Medicina Legal y Ciencias Forenses, Bogotá, Colombia. Electronic address: cmmolinaga@unal.edu.co.
authors.forename: Carlos Martin
authors.initials: CM
authors.lastname: Molina
authors.affiliation: School of Physical Sciences & Geography, Keele University, Staffordshire, ST5 5BG, UK. Electronic address: j.k.pringle@keele.ac.uk.
authors.forename: Jamie K
authors.initials: JK
authors.lastname: Pringle
authors.affiliation: GeoSense, Carrera 7 # 127-48 Of, 1007, Bogotá, Colombia. Electronic address: miguel.saumett@geosenservices.com.
authors.forename: Miguel
authors.initials: M
authors.lastname: Saumett
authors.affiliation: School of Physical Sciences & Geography, Keele University, Staffordshire, ST5 5BG, UK.
authors.forename: Gethin T
authors.initials: GT
authors.lastname: Evans
mesh_terms: D000818:Animals; D002048:Burial; D003105:Colombia; D017097:Electric Impedance; D055590:Electromagnetic Phenomena; D044707:Forensic Sciences / Q000379:methods*; D055593:Geological Phenomena; D006801:Humans; D011825:Radar; D013552:Swine
keywords: Conductivity; Forensic geophysics; Forensic science; Ground penetrating radar; Magnetic susceptibilty; Monitoring; Resistivity; Simulated grave