QUANTIFYING URBAN DAMAGE DUE TO SLOW-MOVING LANDSLIDES: A MULTI-INSTRUMENT AND MULTI-DISCIPLINARY APPROACH

Slow-moving landslides often affect urban areas in many mountainous regions worldwide, causing several problems to buildings and infrastructures. One of the most important actions to address appropriate mitigation and planning measures is to increase the acknowledgement of the phenomena. Thus, an effective approach that combines damage assessment, geotechnical and hydrological evaluation, and comprehensive in-situ and remote monitoring to understand the process becomes necessary. Our work presents a multi-instrument and multi-disciplinary methodology to evaluate impact due to slow-moving landslides. We test it on an area of the Ligurian Alps (north-western Italy), in correspondence with the village of Mendatica. The area of interest is affected by a wide landslide that has caused widespread damage to buildings and other structures in part of the studied area. The site’s high susceptibility to landslides has been studied for a quite long time, and in this paper the authors present a study, which brings together the experience gained and which, by making different monitoring and modelling systems work synergistically, allows for an integrated analysis of slope stability and building damage. Since 2019, the LAMP (Landslide Monitoring and Predicting) has been installed in Mendatica, consisting of a system that allows continuous monitoring of the water content at different nodes and at different depths and the analysis of susceptibility to rain-triggered landslides that may be related to changes in soil moisture or groundwater fluctuations (Bovolenta et al. 2019 and 2020; Viaggio et al. 2022). Furthermore, the monitoring network is accompanied by GNSS displacement measurements, which allow further analysis of the kinematic mechanisms in progress and the control of what LAMP obtains in terms of dynamic maps of landslide susceptibility in the event of observed (or predicted) rainfall. A ground-based monitoring system with a long time series of data is available, and recently, several mitigation works, such as drainage, were predisposed (Pepe et al., 2021).This study used multi-frequency (X, C and L bands) MTInSAR, ground (GNSS, soil moisture sensors) and boreholes (inclinometer, piezometer) monitoring to spatially and temporally assess and characterize landslide kinematic. Jointly, an in-depth damage building survey analysis (Peduto et al., 2017; Cignetti et al., 2024) also allowed us to preliminary estimate the correlation between the degree of damage and the landslide displacement. Preliminary results highlight the critical importance of long-term monitoring data and combined surface and sub-surface measurements (e.g., borehole data) for comprehensively characterizing slope behaviour. Additionally, the accuracy of building settings, during the damage assessment survey, emerges as another key factor for correctly interpreting the deformation-damage correlation. These findings pave the way for future research aimed at developing a standardized method to understand how slow-moving landslides impact structures and buildings.