Application of 3D resistivity model-based inversion in presurvey design for landslide investigation at Sa Pa, Lao Cai, Vietnam

In this study, a new approach was proposed to simulate Electric Imaging (EI) survey in investigations of landslide at a site in Sa Pa, Lao Cai, Vietnam. This research is part of an ongoing GWB project (Giao, 2024). The method utilizes 3D resistivity model-based inversion in combination with a geotechnical-geophysical correlative template to evaluate and select the EI acquisition parameters (e.g., electrode configuration, spacing and level of imaging) for landslide investigation. First, the available 2D EI survey data were collected to create a 3D resistivity model for the study area with landslide occurrence. Iterative forward modeling and inversion are performed to simulate electric imaging survey using Wenner and dipole-dipole arrays. The results show that the dipole-dipole array have a better vertical resolution comparing to Wenner array, and the combination of these two provides the best balance between vertical and horizontal resolution in detecting the low-resistivity weak layer that can act as a sliding surface. This kind of computer-aided pre-survey simulation and design, using robust 3D inversion capabilities of pyGIMLi (Rucker et al., 2017), can improve the accuracy, efficiency and, ultimately, cost of EI survey for landslide characterization.