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

Abstract

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.

Mapping Susceptibility to Debris Flows Triggered by Tropical Storms: A Case Study of the San Vicente Volcano Area (El Salvador, CA)

“…The modeling procedure described in this paper allow for preparing debris flow susceptibility maps by using data typically available on a large scale. In contrast to the previous study [23], which was based on a deterministic approach, the map we obtained depicts the susceptibility to debris flow initiation in a large sector of the San Vicente area, without depending on the actual respondence of local shallow to deep setting to the one hypothesized in 2D modelling; however, according to the factor importance analysis, the statistical model largely fits with physically sound failure mechanisms. At the same time, the pixels in the susceptibility map with high scores could be taken as an input for physical modelling as more likely initiation points.…”

“…The quality of the input data strongly controls the accuracy of the landslide predictive models and the relative susceptibility maps. At the same time, deterministic approaches are critically dependent on very strong hypothesis about mechanical and hydrological properties of rocks, layering and geometrical setting of shallow to deep volumes, failure mechanisms and surface type, triggering rainfall function [23].…”

Monitoring and Mapping of Shallow Landslides in a Tropical Environment Using Persistent Scatterer Interferometry: A Case Study from the Western Ghats, India

“…Combining the PSI information with the slope stability model has significant practical implications. Traditionally, slope stability analysis is performed using physics-based [7] or statistical models [51]. Moreover, the models developed using these approaches are highly conservative, leading to several false positives.…”

“…Landslide triggering mechanisms fall into three critical categories [2]: geological (e.g., seismic activity from other hazards like earthquakes or volcanoes), geomorphological (e.g., changes in slope features through surficial processes), and hydrological (e.g., precipitation, groundwater, or freeze/thaw) [3]. The latter, hydrological triggering mechanisms, are the most prevalent cause of landslides around the world, especially in tropical regions and areas that receive heavy precipitation [4][5][6][7]. Oversaturated, non-cohesive soils and variegated debris may Geomatics 2021, 1 4 come down-slope during or after heavy rainfall [8].…”

Developing a Gis Tool for Infinite Slope Stability Analysis (Gis-Tissa)

“…Landslides are downslope movement of soil, rock, and/or organic matter along a rupture or shear strained surface (USGS, 2008). Landslides occur in response to a triggering mechanism (Varnes, 1978) such as earthquakes, intense rainfall (Smith et al 2015), volcanic eruptions (Schaefer et al 2015;Schaefer et al 2016), weathering, freeze-thaw (Zwissler et al 2014), and flooding (USGS, 2008). A slope prone to instability most likely has many causes, for its failure (Varnes, 1958).…”