3D Archaeological Reconnaissance with Electrical Resistivity Imaging (ERI)
–for the construction of a hydrocarbon pipeline
Archaeologist and Civil Engineers collecting data along the first transect of the ERI survey.
A hydrocarbon pipeline is under constructed outside the city of Hermosillo, Sonora, Mexico. Before construction of the pipeline begins, both surficial and subsurface archaeological reconnaissance work must be carried along the footprint of the hydrocarbon pipeline. This site contains surficial archaeological remains identified as lithic reductions sites by archaeologists from the National Institute of Antropology and History (INAH)-Sonora Center. Lithic reduction sites were once stone tool manufacturing sites used by ancient natives. The main objective of this pseudo three-dimensional (3D) Electrical Resistivity Imaging (ERI) survey was to identify potential major archeological remains within the near subsurface that could affect the construction of the hydrocarbon pipeline.
To map sharply changing geology and soil types with unknown depth and orientation below ground in flat or rugged terrain with direct application to archaeological reconnaissance, civil engineering, geotechnical, water exploration, environmental, and mineral exploration projects.
The pseudo-3D ERI survey was carried on February 8th of 2017. It consists of three (3) parallel two-dimensional (2D) dipole-dipole arrays collected with a SuperSting R8 WiFi, a Switchbox R8, and a set of the FlexLite Passive land cables with 28 electrodes spaced at 2 m intervals. The in-line spacing was 4 m. The parallel transects were combined and processed in AGI EarthImager 3DTM software to create a pseudo-3D inverted resistivity model. The survey site was located in the outskirts of Hermosillo, Sonora, Mexico. The site surface conditions consisted of geomorphologically stable Pleistocene alluvium, which yield favorable contact resistance conditions.
The pseudo-3D dipole-dipole survey successfully imaged the subsurface extend of the two exposed lithic reduction sites. In the 3D inverted resistivity models, the lithic reduction sites show up as high resistivity anomalies within unlithified Pleistocene fluvial deposits, which shown as low resistivity anomalies. The pseudo-3D inverted resistivity model does not reveal the presence of major archaeological remains that could compromise the construction of this important hydrocarbon pipeline.