Evaluation of shallow landslide-triggering scenarios through a physically based approach: an example of application in the southern Messina area (northeastern Sicily, Italy)

L Schilirò,G Scarascia Mugnozza,C Esposito

doi:10.5194/nhess-15-2091-2015

L Schilirò, G Scarascia Mugnozza + Show 1 more

Open Access

https://doi.org/10.5194/nhess-15-2091-2015

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Abstract

Abstract. Rainfall-induced shallow landslides are a widespread phenomenon that frequently causes substantial damage to property, as well as numerous casualties. In recent~years a wide range of physically based models have been developed to analyze the triggering process of these events. Specifically, in this paper we propose an approach for the evaluation of different shallow landslide-triggering scenarios by means of the TRIGRS (transient rainfall infiltration and grid-based slope stability) numerical model. For the validation of the model, a back analysis of the landslide event that occurred in the study area (located SW of Messina, northeastern Sicily, Italy) on 1 October 2009 was performed, by using different methods and techniques for the definition of the input parameters. After evaluating the reliability of the model through comparison with the 2009 landslide inventory, different triggering scenarios were defined using rainfall values derived from the rainfall probability curves, reconstructed on the basis of daily and hourly historical rainfall data. The results emphasize how these phenomena are likely to occur in the area, given that even short-duration (1–3 h) rainfall events with a relatively low return period (e.g., 10–20~years) can trigger numerous slope failures. Furthermore, for the same rainfall amount, the daily simulations underestimate the instability conditions. The high susceptibility of this area to shallow landslides is testified by the high number of landslide/flood events that have occurred in the past and are summarized in this paper by means of archival research. Considering the main features of the proposed approach, the authors suggest that this methodology could be applied to different areas, even for the development of landslide early warning systems.

Highlights

Landslides triggered by rainstorms occur in many parts of the world and cause significant damage and loss to affected people, organizations and institutions as well as to the environment (Glade, 1997; Nadim et al, 2006; Petley, 2012)
The 1 h rainfall amount is lower in the 2007 case (65 vs. 85 mm), the fact that both 1 and 3 h rainstorms with relatively low return period (RP) can cause a substantial instability level emphasizes the severity of recurring rainfall events in the study area and explains the high number of landslide/flood events that have occurred in the past
We introduce an approach for the analysis of shallow landslide-triggering scenarios that uses the TRIGRS code, a physically based model which describes the stability conditions of natural slopes in response to specific rainfall events

Summary

Introduction

Landslides triggered by rainstorms occur in many parts of the world and cause significant damage and loss to affected people, organizations and institutions as well as to the environment (Glade, 1997; Nadim et al, 2006; Petley, 2012) Within this category of natural disasters, shallow landslides (in particular debris flows)can pose a serious threat to life or property, in particular due to their high velocity, impact forces and long runout, combined with poor temporal predictability (Jacob and Hungr, 2005). These phenomena consist of sudden mass movements of a mixture of water and granular material that rapidly develop downslope, eroding the soil cover and increasing their original volume (Iovine et al, 2003).

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