Salvatore Martino

Geological-evolutionary model of a gravity-induced slope deformation in the carbonate Central Apennines (Italy)

This paper discusses the findings from a study conducted on gravity-induced deformationsoccurring along the SW slope of Mount Nuria linking the village of Pendenza (Rieti, Italy) to the area of San Vittorino, in the alluvial plain of the Velino river, where important infrastructures are present. The dominantly carbonate composition of the rocks outcropping along the slope, the occurrence of a main spring fed by a regional karst aquifer and the interaction of gravity-induced deformations with buildings and infrastructures resting on the slope or located at its base make the investigated case extremely interesting and reflective of phenomena that are common in similar geological-hydrogeological conditions. Insights from this case and their use for the construction of a ‘geological-evolutionary model’ shed more light on the complex interactions existing between jointed carbonate rocks, seepage, karst dissolution, genesis of gravity-induced deformations and their evolution in space and time, through the analysis of stress-strain conditions withinthe slope. According to the selected methodologicalapproach, data from detailed geological, geomorphological and geomechanical surveys were integrated with those from laboratory tests and from a complex slope monitoring system. From the results of the study it was possible to: i) refer the investigated phenomena to gravity-induced deformations on the slope scale; ii) build a representative ‘geological-evolutionary model’ and iii) develop an analytical approach to assess the hazard represented by these deformations for local buildings and infrastructures. The identification of different hazard conditions can helpdefine the type and value of possible mitigation efforts. The investigated case also provided inputs for testing new approaches to the geomechanical characterization of rock masses, to the description of their jointing and to the correlation of their main discontinuities with tectonic and gravity-induced elements.

The Large Salcito Landslide Triggered by the 2002 Molise, Italy, Earthquake

The 2002 Molise, Italy, earthquake triggered a deep planar earthslide about 38 km away from the epicenter, mainly involving scaly clay shales and related weathered material. Based on site investigations and borehole data, the inferred depth of the sliding surface is between 30 and 50 meters below ground level, indicating an involved volume of about 40⋅106 m3. The complex geological setting, the generated excess pore water pressure, and possible local seismic response are thought to have been the primary contributing factors.

Numerical modelling of Plio-Quaternary slope evolution based on geological constraints: a case study from the Caramanico Valley (Central Apennines, Italy)

Abstract Evidence of deep-seated gravitational slope deformations (DSGSD) and of large prehistoric landslides is fairly widespread within the Central Apennines (Italy). These gravity-induced processes accompanied the intense Plio-Quaternary uplift phases that affected the mountain chain. In this study a multidisciplinary approach has been adopted in order to better constrain the relationship between the tectonic evolution and the gravitational morphogenesis of a typical Apennine morphostructure, such as the Caramanico Valley. For this purpose a conceptual model of the morphostructural evolution of the area has been reconstructed, on the basis of geological constraints derived by the integration of detailed geological–structural and geomorphological surveys with available literature data. Based on this evolutionary model, a multistage numerical modelling using the finite difference method code FLAC 6.0 has been performed in order to: (i) evaluate the effect of the uplift-related morphological changes of the valley–slope system; and (ii) assess the role of the horizontal/vertical stress ratio variations due to geodynamic regime shifts. The results of the numerical model show a good fit with the actual geomorphical evidence and also confirm the presence during some evolutionary stages of stress–strain conditions compatible with those necessary to produce the massive rock slope failures testified by the presence of large palaeo-landslide deposits.

Earthquake-Induced Reactivation of Landslides: Recent Advances and Future Perspectives

Earthquake-induced reactivation of landslides is a focus topic in risk management as severe damages and losses have been caused so far from seismically-triggered slope failures. Slope stability conditions under seismic action have been studied for several decades by pseudostatic solutions as well as by sliding block methods that follow the Newmark’s approach. These last ones were recently upgraded by flexible block methods to provide a more constrained evaluation of earthquake-induced displacements, i.e. by considering the landslide mass resonance during seismic shaking. Nevertheless, all these solutions cannot take into account the very complex interactions between seismic waves and slope that are pointed out by several case histories reported in the literature. Such interactions can be simulated by more sophisticated stress-strain numerical models that need very strong constraints to both the geological setting of the slope and the local seismic response. In this regard, a fundamental contribution derives from detailed engineering—geological reconstructions as well as on-site geophysical measurements. Recent studies have made use of theoretical approaches for pointing out the significance of some physical parameters, such as the ratios of characteristic periods related to the seismic wave properties and to the landslide mass geometry, to provide a more exhaustive prevision of earthquake-induced landslide displacements.

Forecasting methods for landslides interacting with infrastructures

Few years ago, during the start-up works for the realization of a tunnel entrance, a shallow translational landslide occurred. Following this event detailed engineering-geological surveys of the slope were performed and an integrated monitoring system, including also a Terrestrial SAR Interferometer (TInSAR), was built. Based on the time series of displacement semi-empirical approach was applied to the anchored bulkheads. Simultaneously an engineering-geology model was devised for a stress–strain numerical analysis which was performed by the finite difference code FLAC 6.0.

Soil Liquefaction During the Emilia, 2012 Seismic Sequence: Investigation and Analysis

In the framework of a Project issued by the Italian National Institute of Geophysics and Volcanology (INGV) a Research Unit (RU) has been granted with the commitment to provide a link between the seismic shaking and the triggering of ground failures such as liquefaction. The main goals have regarded both the enlargement of the base of observables for a better constrain of the seismic hazard assessments and the analysis of the triggering and causative factors of permanent ground deformations. Nevertheless, when analyzing the non-linear soil response under which liquefaction occur, some insights into site-effects have been also provided, thus contributing to the general task of the site-specific hazard. The paper illustrates the analyses and investigations carried out within the aim of the project, some of them are still provisional due to the huge amount of data produced and the strong effort required to analyze all the matters related to the observed phenomena.

Multi-sensor system designed for monitoring rock falls: the experimental test-site of Acuto (Italy)

This paper illustrates the design of a multi-sensor monitoring system located in Acuto (Frosinone - Central Italy) where an abandoned quarry was devoted to experimental test-site. The test-site is managed by the Research Centre for the Geological Risks (CERI) and is focused on testing and comparing multi-sensing and multi-parametric remote techniques for early warning, applied to rock falls with strategic infrastructure targets. The final aim of this testing is to process the data collected by techniques integrated by a network of conventional and smart sensors, following observational-bases and statistical approaches. The installed multi-sensor monitoring system consists in 2 control units for weather monitoring, 1 thermometer for the rocky mass temperature, 10 strain-gauges for rock mass joints, 2 optical devices (Smart Cameras) and 1 nanoseismic monitoring network.

Influence of Lateral Heterogeneities on Strong‐Motion Shear Strains: Simulations in the Historical Center of Rome (Italy)

Abstract The influence of lateral heterogeneities on alluvial deposits is a topic of particular interest in the field of urban planning and engineering design of structures and infrastructures. This work focuses on the effects of such heterogeneities on the shear strains produced within the recent alluvial deposits of the Tiber River in the historical center of Rome in case of the worst expected earthquake scenario. To this aim, a 3D engineering‐geology model of the subsoil is used to derive four geological sections across the Tiber River valley as well as 48 soil columns to perform numerical simulations. Various models are considered: a viscoelastic equivalent linear rheology in a 1D finite‐difference model for one‐component horizontal input, a nonlinear elastoplastic model in a 1D finite‐element scheme for three‐component input, and a nonlinear viscoelasto‐plastic rheology in a 2D finite‐difference model under one‐component horizontal input. After comparing these different simulations, results have shown that lateral heterogeneities play a key role with respect to the expected shear strains within multilayered soils. To this aim, some specific indexes are introduced to estimate the maximum shear strain (MSS) concentration within the soil layers as well as to highlight their effect due to the stratigraphic position of the layers, within the soil column, independently from its depth. A final differential index leads to the evaluation of the lateral heterogeneity effect on the estimated MSS, demonstrating their prevalent role with respect to the bedrock shape (i.e., the angle of inclination of the buried valley slopes). From these results, an MSS zoning map is obtained for the historical center of Rome, showing that the local seismic response should be modeled by assuming 1D or 2D conditions depending on the location considered.

High-resolution geological model of the gravitational deformation affecting the western slope of Mt. Epomeo (Ischia)

The recent geological history of Ischia Island is characterized by slope-scale gravitational deformations closely related to volcano-tectonic dynamics of the Mt. Epomeo resurgent caldera. This study focuses on the gravitational deformation that involves alkali-trachytic lava and trachytic ignimbrite flow-units of Mt. Nuovo, located in the western portion of Mt. Epomeo. A preliminary, high-resolution engineering-geological model was obtained through geological, geomorphological and geophysical surveys and reveals a complex morpho-structure with geomorphological evidence of gravitational instability. The complexity of the ongoing slope deformations is confirmed by field geo-structural evidences that led to the identification of a multiple compound mechanism with a main rupture surface which is about 200 m deep. This geometry was better constrained by passive seismic investigations consisting in noise measurements, focused on resonance frequencies of the soil (i.e. based on H/V Nakamura approach). In addition, a close relationship between the outcrop of Mt. Epomeo Green Tuff breccia layers and the distribution of hydrothermal emissions and gas vent can be inferred, as it is related to the higher permeability of the breccia layers with respect to the main Mt. Epomeo Green Tuff flow unit, where the ascent path of deep hydrothermal fluids developed along faults and fracture networks.

Mechanism of the Montescaglioso Landslide (Southern Italy) Inferred by Geological Survey and Remote Sensing

Montescaglioso village is located in southern Italy (Matera, Basilicata region), on a hill top, at about 350 m a.s.l., along the left bank of the Bradano River. Several landslides involved this area, some of them classified as relict; the latest one occurred on December 3rd, 2013 on the south-western slope of Montescaglioso hill. A review of the geological setting of this slope is presented, aimed at defining the failure mechanism of the slope. Sub-pixel cross-correlation analysis based on SAR images was performed to infer the co-failure displacement pattern and A-DInSAR was carried out to detect the spatial-temporal deformational pattern before and after the failure. The field surveys confirmed the main role played by geological setting in structurally constraining the landslide mechanism and its complex kinematic, featured by three main distinct “kinematic blocks” with different direction of movement. The 3rd December landslide has been recognized as a partial reactivation along a slope affected by a long-lasting sequence of landslides, the last one triggered by a transient action.