Hazard assessment of rainfall-induced landslides: a case study of San Vicente volcano in central El Salvador

© 2014, Springer Science+Business Media Dordrecht. The San Vicente volcano in central El Salvador has a recurring and destructive pattern of landslides and debris flows occurring on the northern slopes of the volcano, and in recent memory, there have been at least seven major destructive debris flows. There has been no known attempt to study the inherent stability of these slopes and determine the factors that might lead to slope instability. Past events on the volcano were used to perform a 2D slope stability back analysis and to estimate the unknown model parameters. This analysis confirmed that the surface materials of the volcano are highly permeable and have very low shear strength. Additionally, the analysis provided insight into the groundwater table behavior during a rainstorm. Slope geometry, rainfall totals and initial groundwater table location were found to have the greatest effect on stability. A methodology is outlined for creating a stability chart to be used during rainfall events for monitoring slope stability. This chart could be used by local authorities in the event of a known extreme rainfall event to help make evacuation decisions. Finally, recommendations are given to improve the methodology for future application in other areas as well as in central El Salvador