Identifying the locations of large-scale landslide slip surfaces is extremely difficult and costly, typically
requiring expensive ground surveys. Various methods based on surface displacement monitoring data have been developed to estimate slip surfaces, including the Vector Inclination Method (VIM). However, the VIM has only been validated through field surveys; such surveys are prone to inaccuracies in the data, primarily due to the inherent uncertainties in the monitoring equipment, uninvestigated areas, and the randomness of soil composition. These factors contribute to the overall uncertainty of the survey data and limiting their applicability. Thus, this study conducted numerical simulations to determine surface displacements and slip surface locations during landslides. The data obtained from numerical simulation were used to evaluate and improve on the VIM. This study’s improvements to the VIM yielded
an increase in the VIM’s correlation coefficient, from 0.6 to 0.9.
Key Words: landslide, slip surface, material point method, vector inclination method.