Landslide geometry in urban tropical zones: integrating analyses of ground-penetrating radar and traditional geophysical assessment

Abstract Tropical regions exhibit a high incidence of landslides, primarily driven by the combination of soil composition and precipitation levels. Rapid urbanization further increases this susceptibility by occupying of steeper topographic gradients. While geophysical surveys offer a viable approach to landslide monitoring, there is a scarcity of detailed analyses exploring the full potential of Ground Penetrating Radar (GPR) for delineating landslide dynamics in tropical urban environments. It is often attributed to challenges in deployment on steep slopes and the inherent signal interference generated by urban infrastructure. This paper presents a comprehensive analysis of tropical landslide risk, integrating GPR and Standard Penetration Test (SPT) data from a low-stability slope in Belo Horizonte, Brazil. This urban center is home to approximately 350,000 residents residing in hazard-prone areas. Our investigations successfully identified rupture surfaces characterized by concave curvatures, indicative of rotational sliding, with a calculated potential soil displacement volume of 147.7 m³. The robust correlation between the subsurface layering delineated by GPR and the SPT borehole data strongly corroborates the predominant soil characteristics and moisture content. This study underscores that GPR surveying is a reliable technique for identifying sliding surfaces in landslides and can significantly contribute to forecasting the risk of tropical urban disasters.