Subsurface Geotechnical-Characterization near Some Buildings at the Centro Universitario de la Costa UDG (Puerto Vallarta, Jalisco, Mexico) Using Electrical Resistivity Tomography

Geotechnical studies are essential in civil engineering for all building and infrastructure projects. Typically, in-situ studies involving soil sample collection through drilling are conducted. However, these invasive methods can be costly when numerous boreholes are needed to assess stratum continuity or are impractical for examining subsurface conditions beneath existing structures. Shallow geophysical exploration offers several non-invasive alternatives for subsurface characterization, with Electrical Resistivity Tomography (ERT) being particularly versatile. ERT provides detailed and accurate subsurface images through a relatively simple and fast field implementation. For this study, four 2D ERT profiles were designed and performed near three buildings at the Centro Universitario de la Costa in Puerto Vallarta, Jalisco, Mexico, using a Gito-1100 V resistivity meter from Hematec with Dipole-Dipole arrays. Basic descriptive statistics were calculated for each data set to establish criteria for outlier removal, optimizing the inversion process in Res2DInv software. The inversion results defined five geoelectric units [UG-1 (1 to 20 Ω？m), UG-2 (20 to 40 Ω？m), UG-3 (40 to 100 Ω？m), UG-4 (100 to 500 Ω？m), and UG-5 (750 to 1000 Ω？m)], consistent with previously identified geologic materials. The 2D ERT profiles allowed for the identification of lateral variations in moisture content and saturation and determined the depth of consolidated and possibly cemented materials suitable for future infrastructure projects on the university campus. This work provides a reference framework for implementing the 2D-ERT technique in Puerto Vallarta, supporting its use as a non-invasive alternative for effective subsurface characterization in geotechnical and civil engineering contexts.