A Geomechanical Approach to Landslide Hazard Assessment: The Multiscalar Method for Landslide Mitigation

AbstractThe landslide hazard assessment, when based on the deterministic diagnosis of the processes, can be pursued only through the interpretation and the geo-hydro-mechanical modelling of the slope equilibrium. In practice, though, landslide hazard assessment is still seldom dealt with slope modelling, in particular when it addresses vast areas, where either heuristic or statistical methods do not entail any geo-hydro-mechanical knowledge of slope features and stability. The Multiscalar Method for Landslide Mitigation (MMLM) is an original methodological approach for intermediate to regional landslide hazard assessment. It is based on the geo-hydro-mechanical knowledge achieved from the application of a stage-wise diagnostic methodology of the landslide mechanism at the slope scale. The paper discusses the main steps of the MMLM aiming at diagnoses of landslide hazard based on hydro-mechanics, for small scale hazard mapping (at the large area)

Multi-scale approach to analyse the evolution of soft rock coastal cliffs and role of controlling factors: a case study in South-Eastern Italy

The evolution of soft rock coastlines is strictly related to natural and anthropogenic conditions, which in some cases can determine also an acceleration of coastal retreat. The recent evolution of a soft rocky coastal stretch on the Italian southern Adriatic sector is analysed. To investigate the most important contributing factors to coastal evolution, a detailed multi-temporal (1954–2017) morphological analysis with photo-interpretation is carried out, which allows gaining a general understanding of the cliff evolution. The coastal retreat was then evaluated by exploiting the Digital Shoreline Analysis System (DSAS) tool. From that, site-specific analyses are carried out to explore the role of four environmental factors: rock mechanical properties, geostructural setup of the rock mass along the coast, emerged rock platform at the toe, and the storm waves. Analyses highlighted how the most significant retreat is detected along cliff segments characterized by the presence of low strength rocks susceptible to water-induced weakening, moderate fracturing degree of the rock mass, absence of the emerged platform at the toe, and wave storms. This work shows how a multi-scale methodology could represent an efficient approach to gain an interpretation of the instability processes and thus prepare risk mitigation plans and land management strategies

A hydrogeological study to support the optimized management of the main sea level aquifer of the island of Malta

Management groundwater resources, coastal aquifer, seawater intrusion, safe-yield, Malta

Analisi tridimensionale agli elementi finiti di una frana in argille innescata da scavo al piede e verifica della strategia di mitigazione del rischio

Le frane di prima attivazione di versanti in argille consistenti sature, innescate da scavo al piede nel lungo periodo come conseguenza dei processi di consolidazione negativa delle pressioni interstiziali, sono state nel tempo oggetto di numerosi studi. Una frana di questa tipologia ha interessato tra il 1980 ed il 1998 un versante in argille pleistoceniche a nord della città di Lucera (Foggia). Lollino e coautori (2011) hanno presentato una interpretazione dettagliata dell’evoluzione tenso-deformativa del versante nel tempo fino al raggiungimento delle condizioni di collasso con l’ausilio di analisi bidimensionali. Nel presente lavoro è stato sviluppato un modello tridimensionale agli elementi finiti del versante nell’ipotesi di comportamento elasto-plastico drenato del terreno al fine di indagare l’evoluzione 3-D del processo di frana; ulteriori analisi numeriche sono state quindi condotte per verificare l’efficacia degli interventi di mitigazione del rischio messi in opera in anni recenti. I risultati del modello sono in accordo con le osservazioni di sito e confermano che la strategia di intervento adottata sia da considerarsi efficace rispetto all’obiettivo di stabilizzazione del versant

An interdisciplinary approach to landslide damage assessment in urban areas

This paper presents some results of a multidisciplinary research about the assessment of damages to ordinary buildings at the urban scale in landslide areas. The methodology represents part of a multi-level approach for landslide vulnerability assessment that has been recently developed. It is based on rapid visual inspections of the buildings, the application of ‘simple models’ to interpret the structural response, the geological and geotechnical knowledge of the site. The end-product is the landslide damage geotechnical chart, including: i) the damage grade of the buildings, ii) the geomorphological and geotechnical map of the area, iii) the direction of the settlements causing damages. The application of the methodology to an historical site in southern Italy is also outlined. Finally, the contribution of innovative non-invasive spaceborne remote sensing techniques to monitor landslide-affected urban areas is highlighted

Multi-scale approach to analyse the evolution of soft rock coastal cliffs and role of controlling factors: a case study in south-eastern Italy

The evolution of soft rock coastlines is strictly related to natural and anthropogenic conditions, which in some cases can determine also an acceleration of coastal retreat. The recent evolution of a soft rocky coastal stretch on the Italian southern Adriatic sector is analysed. To investigate the most important contributing factors to coastal evolution, a detailed multi-temporal (1954–2017) morphological analysis with photo-interpretation is carried out, which allows gaining a general understanding of the cliff evolution. The coastal retreat was then evaluated by exploiting the Digital Shoreline Analysis System (DSAS) tool. From that, site-specific analyses are carried out to explore the role of four environmental factors: rock mechanical properties, geostructural setup of the rock mass along the coast, emerged rock platform at the toe, and the storm waves. Analyses highlighted how the most significant retreat is detected along cliff segments characterized by the presence of low strength rocks susceptible to water-induced weakening, moderate fracturing degree of the rock mass, absence of the emerged platform at the toe, and wave storms. This work shows how a multi-scale methodology could represent an efficient approach to gain an interpretation of the instability processes and thus prepare risk mitigation plans and land man agement strategies

Regional-Scale Seismic Liquefaction Susceptibility Mapping via an Empirical Approach Validated by Site-Specific Analyses

Regional-scale analyses of susceptibility to liquefaction are seldom performed in data-scarce areas. However, in spite of data limitations, such efforts can still provide useful information in case of populated, seismically active regions. The present work focuses on susceptibility zonation for soil liquefaction that might occur due to ground shaking in the Foggia Province, a data-scarce, seismically active area of about 7000 km2 located in southern Italy. The Analytical Hierarchy Process (AHP) approach is used to obtain the susceptibility to liquefaction map of the whole area, while a geological and geotechnical database including 531 boreholes from 84 localities is used for cross-validation. The data are processed by means of a simplified quantitative method to determine liquefaction potential and assess whether a specific area is prone to liquefaction or not. Our results, along with an AUC − ROC = 0.89 test value, indicate that there are widespread areas of medium to high and very high susceptibility, and that the most susceptible zones are localized along the Adriatic Sea coastline and watercourses. The final susceptibility to liquefaction map represents a step forward towards the assessment of secondary seismic hazard in the study area, thus supporting the regional and local administrations responsible for land-use planning and risk mitigation

The relation of spatio-temporal distribution of landslides to urban development (a case study from the Apulia region, Southern Italy)

The paper describes the multitemporal landslide inventory map prepared for the urban areas of Motta Montecorvino and Volturino, two municipalities located in the Southern Apennines (Apulia Region, Italy). These territories show a high propensity to landslides of different types and magnitude, which periodically interfere with the anthropic structures and infrastructures. For the study area, the spatial and temporal distribution of landslides is detected for the period between 1954 and 2003, through the visual interpretation of multiple sets of black and white digital stereoscopic aerial photographs at different scales. The analysis reveals locally high frequency of landslide occurrence and built-up areas on existing landslides, either on the body or on the crown areas. In particular, we show that over the years new residential areas were developed despite the presence of large old mass movements

Regional-Scale Seismic Liquefaction Susceptibility Mapping via an Empirical Approach Validated by Site-Specific Analyses

Regional-scale analyses of susceptibility to liquefaction are seldom performed in data-scarce areas. However, in spite of data limitations, such efforts can still provide useful information in case of populated, seismically active regions. The present work focuses on susceptibility zonation for soil liquefaction that might occur due to ground shaking in the Foggia Province, a data-scarce, seismically active area of about 7000 km2 located in southern Italy. The Analytical Hierarchy Process (AHP) approach is used to obtain the susceptibility to liquefaction map of the whole area, while a geological and geotechnical database including 531 boreholes from 84 localities is used for cross-validation. The data are processed by means of a simplified quantitative method to determine liquefaction potential and assess whether a specific area is prone to liquefaction or not. Our results, along with an AUC − ROC = 0.89 test value, indicate that there are widespread areas of medium to high and very high susceptibility, and that the most susceptible zones are localized along the Adriatic Sea coastline and watercourses. The final susceptibility to liquefaction map represents a step forward towards the assessment of secondary seismic hazard in the study area, thus supporting the regional and local administrations responsible for land-use planning and risk mitigation