Landslide Failure Surface and Volume Estimation Using a Sloping Local Base Level (SLBL) Method: A Case Study

The mountainous regions are prone to multiple natural disasters. Landslides are one of the frequent hazards triggered by heavy rainfall, earthquakes, or controlled by complex geological conditions. Characterizing the landslide failure surface and its volume provides a fundamental understanding of its behaviour and risk assessment. The failure surface and volume constrain the propagation of a landslide and also the related debris flow runout. These are important aspects of landslide analysis and are essential for understanding the magnitude of the event, its impact on the environment, and the potential for future events. The most straightforward initial estimate is made using the product of the surface area and the average depth of the failure surface, known as the planimetric method. The method might overestimate or underestimate the results. However, it can be refined based on the surface information or subsurface data. The sloping local base level (SLBL) method provides a genuine approach to estimate the volume involved and potential failure plane based on surface topographic data from existing DEMs or gridded data acquired using other remote sensing instruments. The SLBL solution results in a surface with a constant curvature, which implies a quadratic surface with a constant second derivative along the xz and yz planes. This study discusses a detailed methodology and the applicability of SLBL in estimating the volume and failure surface reconstruction of the Santa Lucia landslide, Patagonia, Chile.