Assessment of post-failure evolution of a large earthflow through field monitoring and numerical modelling
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P. Lollino I D. Giordan I P. Allasia I N. L. Fazio I M. Perrotti I F. Cafaro
Assessment of post-failure evolution of a large earthflow through field monitoring and numerical modelling
Abstract The analysis of the residual hazard existing after the emergency phases generated by the activation or reactivation of landslides is rarely taken into account in a proper manner. However, the assessment of landslide post-failure evolution should represent a key factor to control potential landslide reactivations and prevent new landslide-induced damages. This paper presents the results of a long-term field monitoring activity performed in the years after the emergency phase of the Montaguto (Italy) earthflow reactivation occurred in 2010 as well as the results of 2-D and 3-D numerical analyses aimed at interpreting the postemergency landslide behaviour. The results of the numerical simulations, which agree well with the in situ monitoring data, allow to define a conceptual model of the earthflow behaviour that is related to the pore water pressure variations resulting from the drained or undrained processes occurring in the landslide body. The study proposed confirms a general reduction of the landslide activity, as well as allows to detect the factors that control the residual activity existing in a specific area of the landslide and to infer possible critical scenarios for landslide reactivations. Keywords Near real-time monitoring . Numerical Modelling . Earthflow . Post-emergency evolution . Residual hazard Introduction The application of real-time or near real-time monitoring is widely considered to be the most efficient way to control the hazard associated with the unstable areas of a landslide during the most critical phases, and to support the risk management related to the landslide failure (Manconi and Giordan 2016). Monitoring networks generally provide an efficient support to manage an earlywarning system for public safety or risk management purposes (e.g. Crosta et al. 2015; Giordan et al. 2019; Intrieri et al. 2019). However, a more comprehensive understanding of the landslide behaviour and the kinematical evolution, as well as of the corresponding controlling factors, can be more reliable when supported by the results of the application of numerical modelling techniques. As such, modelling can provide a physically or mechanically based conceptual and interpretative model of the landslide process, to be calibrated by means of the same field monitoring data (Picarelli et al. 2005; Cotecchia et al. 2015; Lollino et al. 2016). In particular, detailed studies concerning the interpretation of flow landslide mechanisms, based on both the available monitoring dataset and the results of numerical modelling, have been proposed by Picarelli et al. (2005, 2008), Tacher et al. (2005), Schulz et al. (2009), Conte et al. (2014), Bernardie et al. (2015) or, for the case of slow deep-seated sliding mechanisms, by Corominas et al. (2005), Crosta et al. (2014), Fernandez-Merodo et al. (2014), Lollino et al. (2016), Bru et al. (2
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