Orlando Hernández

Preliminary results of sequential monitoring of simulated clandestine graves in Colombia, South America, using ground penetrating radar and botany

In most Latin American countries there are significant numbers of missing people and forced disappearances, 68,000 alone currently in Colombia. Successful detection of shallow buried human remains by forensic search teams is difficult in varying terrain and climates. This research has created three simulated clandestine burial styles at two different depths commonly encountered in Latin America to gain knowledge of optimum forensic geophysics detection techniques. Repeated monitoring of the graves post-burial was undertaken by ground penetrating radar. Radar survey 2D profile results show reasonable detection of ½ clothed pig cadavers up to 19 weeks of burial, with decreasing confidence after this time. Simulated burials using skeletonized human remains were not able to be imaged after 19 weeks of burial, with beheaded and burnt human remains not being able to be detected throughout the survey period. Horizontal radar time slices showed good early results up to 19 weeks of burial as more area was covered and bi-directional surveys were collected, but these decreased in amplitude over time. Deeper burials were all harder to image than shallower ones. Analysis of excavated soil found soil moisture content almost double compared to those reported from temperate climate studies. Vegetation variations over the simulated graves were also noted which would provide promising indicators for grave detection.

Assessing intraplate earthquake hazards from satellite geopotential field observations

Satellite magnetic and gravity field observations provide important constraints on the poorly understood lithospheric properties of intraplate earthquakes because they map lateral long-wavelength contrasts in magnetization and density, respectively, related to petrological, structural, and thermal variations that help control the distribution of lithospheric stress. These anomalies are each a product of the vertically integrated physical property times the layer thickness. Thus, they constrain and enhance the geological utility of near-surface geopotential surveys, as well as seismic, GPS, and other geophysical observations that map the geological and dynamic properties of the lithosphere. To illustrate this synergy, we consider the influence of the US Transcontinental Magnetic Anomaly (TMA) on crustal stress and earthquake activity along the 38th parallel. In another example, we compare crustal earthquake stress constraints from gravity and seismic observations of the US mid-continent and North Andes microplate where starkly contrasting plate tectonic forces operate.