Gravimetric study of a retrogressive landslide in Southern Italy

Journal of Maps, 2015

The Scrivia river is a right tributary of the Po river, the main Italian water course, which flows eastwards into the Adriatic Sea. The head of the Scrivia valley is located in the Northern Apennines, a very short distance from the Ligurian Sea. Its catchment is characterized by landslide areas greater than both the regional and national average. In this work, the causes of this high landslide density have been investigated and a large-scale map of landslide phenomena is produced. Based on geomorphological constraints, several previously unknown deep-seated gravitational slope deformations (DSGSDs) were also identified. DSGSDs have been distinguished in sackungen and lateral spreads. Their characteristics were analyzed in a geographical information system (GIS) environment and compared with landslide distribution. Field surveys, aerial photo-interpretation and GIS analyses led to the production of a large-scale landslide and DSGSD overview map at 1:35,000. The massive presence of DSGSDs and their connection to landslide distribution and activity raise important implications for both geological mapping and land planning.

Natural Hazards and Earth System Science, 2013

Journal of Maps, 2015

This work presents the first results of an integrated geomorphological analysis of a large earthflow in Montebello sul Sangro (Abruzzo, Central Italy). The study is based on a multitemporal geomorphological investigation supported by the morphometric analysis of the drainage network and numerical landslide modelling. The multitemporal geomorphological investigation, based on the interpretation of aerial photos, LiDAR data and field geomorphological mapping, outlined the recent geomorphological history and multiple activation phases of the landslides. A 2D Finite Difference Method (FLAC, Fast Lagrangian Analysis of Continua) analysis of the main landslide scarp, affecting the village of Montebello sul Sangro (Italy), was performed. Finally, in order to outline the morphometric features of the landslide area, local slope autocorrelation was used as a morphometric index. The analysis was aimed at studying the evolution of the active current landslide and specifically the possible retreat of the main scarp.

Engineering Geology, 2023

A methodological approach based on the integration of different survey techniques may be particularly suitable for the study of areas with complexgeology such as those affected by landslide phenomena. The results obtained by the application of combined electrical resistivity tomography (ERT) technique, ambient seismic noise measurements (single station and array), geological investigation and granulometric analysis to characterize and study a landslide occurred on December 3rd, 2013 in Basilicata region (southern Italy) are presented and discussed. The landslide partially affected the peri-urban area of Montescaglioso town and caused damages to smallmedium enterprises, infrastructures, and housing. The analysis of ambient noise signals made possible to estimate the depth of the contacts between the main geological formations outcropping in the area and revealed the existence of directional resonance effects. The discontinuities observed by the ERT have confirmed the presence of different lithotypes and allowed illuminating the sliding surface at a depth of about 40 m in agreement with the seismic results and boreholes data. The shallow discontinuities inferred from geophysical surveys were supported also by the results of a detailed granulometric analysis performed on a geognostic survey, confirming the presence of a heterogeneous sedimentary deposit in the area. In such complex context, the acquisition of spatially distributed geophysical properties permitted to increase the knowledge of the geological setting of the area, reaching a level of detail that cannot be observed by applying only a sparse discrete direct sampling. The integration of all the obtained information allowed the delineation of geophysical discontinuities related to the presence of sliding or weakness surfaces and areas with high water content that could contribute to future activation of the movement. This information was crucial to better understand the nature of the landslide, contributing to the planning and the implementation of risk mitigation actions and to the design of remediation works.

Landslides, 2020

On 25 and 29 January 2019, a large landslide destroyed an important part of the town of Pomarico (Basilicata Region, Southern Italy). Geological and geomorphological investigations provided a detailed description of the landslide features. Several geophysical surveys were carried out to deepen knowledge of the landslide and the residual risk assessment. Detailed electrical resistivity tomography (ERT), multichannel analysis of surface waves (MASW), and seismic refraction tomography (SRT) have been used to analyze geomorphological evidences of the failure and the potential kinematic evolution of the landslide scarp, a crucial factor to assess landslide residual risk. The joint analyses of the geophysical results, compared with geological and geomorphological data, allowed to obtain detailed information about the stratigraphic contact between clayey and sandy deposits in the crown area of the landslide, and to identify the post-failure stability condition changes in sands. The geophysical analyses confirmed the presence of multiple old degraded scarps developed over time and provided information on the decompression state of the different areas of the landslide crown. The results highlighted a subparallel stratification consisting of an anthropic surface carryover material, which covers a layer of sands with silty intercalations, overlying clayey material that represents the bedrock of the investigated area. Furthermore, natural and anthropogenic caves, mainly developed in well-cemented layers of sands, were identified. This study emphasized how the integration of different geophysical methods constitutes a capable tool for characterizing landslides, contributing to assessing the landslide residual risk of the slope mass and evaluating the suitability of the methods in relation to the investigated landslide conditions.

Geomorphology, 2014

On 15 February 2010, as a result of intense and long-lasting rainfalls, a large landslide affected a wide area near the town of Maierato (Calabria, Italy). The studies conductedincluding (i) aerial photo interpretation, (ii) geological and geomorphological field investigations, (iii) interpretations of lithology and stratigraphy from borehole data, and (iv) observation of videos filmed during the main diastrophic phases of the landslide and of antecedent Google Street View® imagesallowed researchers to reconstruct the geological and tectonic setting of the slope and the internal structure of the landslide with the estimation of the depth of the sliding surface, the triggering mechanisms and its evolution. The analysis of the prelandslide event setting demonstrates that this mass movement is the reactivation of a preexisting landslide of alleged seismic origin, remaining at an incipient stage. The Maierato landslide occurred on a gentle slope made of late Miocene to Plio-Pleistocene clastic and evaporitic sedimentary rocks. The main basal failure surface that developed on the hemipelagic marls has a maximum depth of 50 m. The volume of the landslide is~5 million cubic meters. The type of landslide movement is a complex one, consisting of a very rapid slide of rock and earth and of flow of debris and earth. The landslide clearly shows three major types of failure mechanisms: the first type is described as a rapidly moving rotational slide where back-tilted blocks of sediment are preserved; the second type includes a very rapidly moving translational slide of large rock blocks; the third type includes sudden, extremely rapid flow-slides where the slide material is disaggregated while flowing downward along a gentle slope. The slide is a compound one, with a retrogressive evolution and transformation into earth and debris flow during the failure. After the triggering of the landslide, and as a result of the relevant displacement, an important portion of the lower evaporitic unit (Calcare di Base Formation), close to the failure surface, collapsed, thereby undergoing a quick change of its mechanical behavior that became similar to that of a viscous fluid. During the landslide evolution, large rocky blocks consisting of Miocene evaporitic limestones, Pliocene silty clays, and sands were rafted, without severe disturbance, on the destructurated and fluidized limestone. The intense destructuration and the presence of water transformed the limestone (in the lower parts of the unit) into a viscous material that was squeezed out of the landslide mass through the jags between the several rafted rocky blocks and along the natural levees of flow tongue. This event is a rather frequent combination of mass movements made complicated and spectacular by the fluidization of the weak limestone that imparted great dynamics to the movements. Such fluidization is an infrequent phenomenon especially in this geological context.

Geomorphology, 2005

The present paper describes a multidisciplinary approach to the evaluation of a seismically triggered landslide that occurred in the Cerda area (Italy) on September 6, 2002, about 1 h after an earthquake took place in the south Tyrrhenian Sea. The study was focused on an analysis of the role of the seismic input in triggering the landslide, in view of the evidence that no other mass movement was recorded in the adjacent areas despite geological and geomorphological spatial homogeneity. The studied area is located on a slope of the western flank of the Fiume Imera Settentrionale (Northern Sicily), which is made up of clayey–arenitic rocks. The slope inclines gently but is not uniform due to fluvial, gravitative, and rainwash processes. Field data dealing with global positioning system (GPS), geology, geomorphology, geophysics (vertical electrical sounding, or VES), and geochemistry (soil gas fluxes and composition) were acquired and analysed in order to investigate the cause–effect relationships between the earthquake and the mass movement. The GPS survey allowed us to map the ground failures that have also been classified on the basis of their kinematical meaning (i.e., compressive, distensive, or transcurrent structures). The geological analysis revealed outcropping rocks and tectonic structures. The geomorphologic survey highlighted the presence of preexisting landslide bodies. The geophysical survey detected a buried surface located at a depth of about 100 m . Finally, the geochemical survey showed that the gas released from the displaced mass came from a shallow depth and was not related to any active fault system. The abovementioned information allowed us to interpret the landslide event as a partial reactivation of a preexisting landslide body that was triggered by the earthquake.

Journal of Maps

This work deals with the landslides affecting the area surrounding the village of San Martino sulla Marrucina and involving the neighboring municipalities of Casacanditella and Filetto. The geological and geomorphological settings of this area are being discussed. The enclosed maps have been realized following a multidisciplinary approach, based on morphometric, geological, and geomorphological analyses and supported by air-photo interpretation, dendrochronology, and satellite SAR interferometry (InSAR). The map is organized in four sections: orography (on the upper part), geological map (on the upper right part), main geomorphological map (in the central left part, 1:7,500 scale), and multitemporal analysis (in the lower part). The aforementioned multi-temporal assessment of landslides was performed according to the geomorphological evidence-based criteria and the past ground displacement measurements were obtained by dendrochronology and InSAR. The aim of the study is to understand the evolution in time and space of this landslide area, focusing on the corresponding kinematics.

Landslides

On 15 February 2010, a landslide of great dimensions occurred at Maierato (Calabria, Southern Italy) after a long rainy period. Although the zone was continuously affected by ground movements especially during the wet seasons, no monitoring system was installed before the occurrence of the landslide. However, many photos and two videos were taken during the failure process of the slope. In the present study, the available images are used to reconstruct the kinematics of the landslide. In addition, a finite element analysis is performed to define the main factors of triggering and to interpret the failure mechanism of the slope. This analysis is also based on the data from a site investigation carried out after the landslide to characterise the involved soils from a geotechnical viewpoint. The analysis also accounts for the strainsoftening behaviour of some soils. The results have shown that the Maierato landslide was the reactivation of a pre-existing landslide body, which was caused by a significant increase in groundwater level.

2013

2008

The Ballantrae Complex, SW Scotland, is an ophiolitic assemblage of mostly Early and early Middle Ordovician age (Tremadoc-Arenig in terms of the British Ordovician Series). Its varied components were generated and assembled in the Iapetus Ocean, then obducted onto the Laurentian continental margin by the earliest Llanvirn. The timing of obduction is constrained by biostratigraphic and radiometric data. It was most probably a polyphase process initiated at about the beginning of the Arenig, at about 478 Ma. However, parts of the Complex are significantly younger, with some recent evidence taken to suggest an earliest Llanvirn age of about 464 Ma for the emplacement of some of the volcanic and pelagic sedimentary rocks. The oldest strata in the succession that now unconformably overlies the Ballantrae Complex were deposited at about 463 Ma. Hence there may have been as little as one million years available for the final stages of the Complex's tectonic assembly, obduction, uplift, erosion and downfaulting. Obduction of the Complex has been invoked as a factor in the initiation of the Grampian Orogeny, and whilst there is a broad correlation in timing, the detail from Ballantrae militates against a causal relationship.

The paper presents the phenomenological interpretation of the failure mechanism involving an active and complex landslide process within the Pisciolo hill-slope (Southern Apennines, Italy). The sliding process interacts with important infrastructures that in the last decade have undergone recurrent damage, prompting a comprehensive investigation and monitoring of the slope features and processes. Based on the study of all the investigation data, the interpretation of the failure mechanism has required the creation of the geological and the geotechnical model of the slope along with the reconstruction of the slope history. The case is representative of the slow evolution of landsliding typically occurring in chain areas where the outcropping clayey soils are extensively disturbed and fissured as result of intense long-lasting tectonics.

2005

This paper reports the results of geological and geomorphological surveys and the first results of a still in progress GPS monitoring campaign, taken on a large and ancient landslide located near Avigliano town (Basilicata region, South Italy). The landslide occurs on structurally complex clayey-marly terrains and it is classifiable as a multiple and complex roto-translational-earthflow landslide. In the last years this landslide has been affected by frequent reactivations that have been the cause of grave damages to the urban structures in the area. During January 2004, in order to monitor the present kinematics of the landslide body, a GPS network was installed. Until today several GPS surveys have been carried out. The results of GPS data analysis show centimetres level motions going on the landslide. The final goal of the research will be to define a hazard evaluation and an evolution model of the landslide, using the integrated information coming from GPS and geomorphological s...