Geophysical characterization, design and construction of the Teoloyucan Geophysical Test Site for archaeological and engineering applications, Central Mexico

Abstract

Abstract The Teoloyucan Geophysical Test Site (TGTS) is designed to replicate and simulate scenarios encountered in engineering and archaeological contexts. It is meant for calibrating instruments, testing near-surface geophysical techniques, training students and developing new ideas for shallow surveys and data interpretation. TGTS has been built within the Teolyucan Geomagnetic Observatory of the Universidad Nacional Autonoma de Mexico (UNAM) in the town of Teoloyucan, N of Mexico City. The test site covers an area of 864.00\xa0m 2 , consisting of 17 structures buried less than 2.00\xa0m deep with regular and irregular shapes, and vertical and horizontal layers simulating stratigraphic sequences. We selected materials similar to those commonly used since the Pre-Hispanic period (adobe, wood, basalt , tezontle), and current materials (concrete, reinforced concrete, plastic containers and PVC). Prior to the construction, the field area was characterized by a combination of non-invasive near-surface geophysical techniques including magnetic gradiometry, electromagnetic induction, ground penetrating radar, seismic refraction tomography and electrical resistivity tomography. The structures physical properties (density, elastic modules, electrical conductivity and magnetic susceptibility) and their geometrical characteristics are well known, therefore the near-surface geophysical response of the TGTS is controlled. The geophysical results indicate three flat interfaces at approximate depths of 0.45\xa0m, 0.91\xa0m and 1.82\xa0m, respectively. The lithological analysis indicate that the layers are well graded coarse soil layers, including two volcanic hard-horizons ( tepetates) . Geophysical results coincide with Teoloyucan s lithology , proving that the field area selected is suitable for a test site.