The study of a large slide of natural slopes in mountainous areas of south Brazil

The article presents the geological analysis, field monitoring, and interpretation of a large landslide involving rock and soil, which occurred on the edge of the Basaltic Plateau in Malhada, Rio Grande do Sul, Brazil. The investigation included slope stability analysis based on the original 1964 topography, shear strength measurements in the laboratory, and pore water pressure data recorded in the field. The results allowed the reproduction of the conditions responsible for the initial failure. The total volume of displaced material was estimated at approximately 15 × 10⁶ m³. The study suggests that the mass movement is an important example of the geomorphological processes acting on the evolution of the basaltic escarpment, highlighting the influence of factors such as rock material characteristics, hydrological conditions, and stresses acting on the slope over time. The results contribute to understanding the instability mechanisms in mountainous regions, with direct implications for geotechnical risk management in areas susceptible to mass movements.