A pre-existing and inherited geostructural setting plays a fundamental role in preparing and developing large-scale slope deformational processes. These structures affect the kinematics of the ...process, the geometrical characteristics, and the geomorphological evolution. In the Apennine Belt, several deep-seated gravitational slope deformations (DSGSDs) that have evolved under a clear structural control have been recognized during the last decades, but none with a continuous and well-defined basal shear zone (BSZ). The structurally-controlled DSGSD of Luco dei Marsi represents the first case of a DSGSD in the Apennine Belt with a well-defined BSZ. Starting from a detailed study of the process and the reconstruction of a morpho-evolutionary model of the slope, a series of numerical modelings were performed for the study of the DSGSD. The analyses allowed us to reconstruct: (i) the mechanism of the process, (ii) the rheological behavior of the rock mass, and (iii) the main predisposing factors of the gravitational deformation. Numerical modeling has demonstrated the significant role played by the inherited structures on the DSGSD and, in particular, the importance of an intensely jointed stratigraphic level in the development of the BSZ.
The availability of high-quality surface data acquired by recent Mars missions and the development of increasingly accurate methods for analysis have made it possible to identify, describe, and ...analyze many geological and geomorphological processes previously unknown or unstudied on Mars. Among these, the slow and large-scale slope deformational phenomena, generally known as Deep-Seated Gravitational Slope Deformations (DSGSDs), are of particular interest. Since the early 2000s, several studies were conducted in order to identify and analyze Martian large-scale gravitational processes. Similar to what happens on Earth, these phenomena apparently occur in diverse morpho-structural conditions on Mars. Nevertheless, the difficulty of directly studying geological, structural, and geomorphological characteristics of the planet makes the analysis of these phenomena particularly complex, leaving numerous questions to be answered. This paper reports a synthesis of all the known studies conducted on large-scale deformational processes on Mars to date, in order to provide a complete and exhaustive picture of the phenomena. After the synthesis of the literature studies, the specific characteristics of the phenomena are analyzed, and the remaining main open issued are described.
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Physical properties and mechanical parameters of intact rocks are essential in defining geomechanical characteristics of rock masses. The latter are fundamental in the geotechnical design and ...numerical modelling of engineering-geological applications involving slope stability analyses as well as the design of dams, foundations, tunnels, open and underground mines, nuclear storage repository etc. Time and financial constraints of many projects often do not allow to perform all the laboratory tests necessary for physical-mechanical characterization of the rock matrix. In these cases, existing published data are the only tools for appropriate definition of the geomechanical characteristics of the intact rocks and subsequent development of engineering-geological performances.
This paper reports the values of major physical properties and mechanical parameters for several intact rock samples of limestone, collected from the Central Apennines region (Italy). The main physical properties measured for the rock samples are unit weight, density, and porosity. The mechanical parameters derived from the laboratory tests on the samples include uniaxial compressive strength, cohesion, friction angle, tensile strength, elastic modulus, and Poisson's ratio. Only for a few of samples, the index parameters (point load index) and the dynamic characteristics (P-wave velocity) were also measured. The laboratory tests for these samples were performed following the standards by the International Society for Rock Mechanics (ISRM).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
This paper focuses on Deep-Seated Gravitational Slope Deformations (DSGSDs) identified in the Molise region (Italy), along the central-southern sector of the Apennines chain. These phenomena were ...detected and mapped through a combination of aerial-photo interpretation, morphological analyses, and field surveys, integrated through satellite SAR interferometry (InSAR). The obtained general map is organized in different sections: inventory map with identification of DSGSDs and main geological and orographic features, geostructural scheme, representative cross sections, list and characteristics of DSGSDs, geomorphometric maps, landslides map, and seismotectonic setting. This study allowed us to realize a complete inventory of DSGSDs in the Molise region and define the main characteristics of each phenomenon. Through this research, it was possible to establish a general correlation between the analyzed deformations and the geological and geomorphological setting of the region as well as with its geodynamic context.
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This paper presents a morphometric and structural-geomorphological approach to identifying morphotectonic features across an area underlain by lithologies that do not easily record tectonic ...deformations but are widely affected by seismic activity. The middle Biferno River Valley (Central Italy) was chosen as a study area. It was investigated through analyses performed from the drainage basin scale (Biferno River) to the local scale (Ponte Liscione Dam). This methodological approach was applied to investigate the impact of morphotectonic processes in the study area, providing a geomorphology-based contribution to landscape evolution. The aim of the work was to discriminate the main morphotectonic elements acting in the complex tectonic framework of the study area by means of a combination of morphometric, morphotectonic, and structural-geomorphological analyses. The resulting data allowed us to identify three main systems of tectonic elements (F1, F2, and F3), which are attributable to compressive and extensional kinematics, as already reported in previous thematic studies. The tectonic setting reflects the geodynamic framework of the Periadriatic region, as highlighted by the distribution of seismogenic sources and the historical to recent seismicity. Finally, the present work could act as a valuable scientific tool for any geomorphological studies aimed at better defining the impact of morphotectonic processes in similar tectonically active regions hosting important and strategic artificial dams.
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Different soil cover saturation has a significant effect in influencing slope stability conditions of weathered covers under earthquake-induced shaking. Here we analyze the Montecilfone, Italy ...(2018), case history, an Mw 5.1 earthquake that revealed an exceptionality in the spatial distribution of the surveyed earthquake-induced shallow landslides. This feature can be justified as intense rainfall occurred in the epicentral area before the seismic event, contributing to increasing the saturation and the weight of the soil covers. To verify the effective influence of antecedent rainfall as a preparatory factor in the earthquake triggering of soil covers, stability conditions for both static and dynamic scenarios were validated by reconstructing different saturation conditions related to a rainfall event that occurred before the earthquake. Soil cover surveying was performed within a 150 km2 area to output its spatial distribution in terms of their compositional features and thickness, whose variability was constrained through empirical models. Based on laboratory test results, 1D infiltration numerical models were performed through the Hydrus-1D free domain software to estimate the saturation degree of the soil cover and the water infiltration depth, taking as a reference the intensity of the rainfall event. Soil cover sequential charts of water content were obtained at different depths and times up to those recorded at the time of earthquake occurrence by the performed numerical modelling. Safety factors (SFs) of the slope covers were quantified assuming an unsaturated condition in the slope stability equation. The outputs reveal that pore pressure spatial distribution in the unsaturated medium infers on the earthquake-induced scenario of shallow landsliding, demonstrating its role as a preparatory factor for earthquake-induced shallow landslides.
In this paper, a geomorphological map of Pescara del Tronto area (Sibillini Mts, Marche Region) is presented. The work focuses on the geomorphological analysis performed in a zone strongly struck by ...the 2016-2017 seismic sequence of Central Apennines. The geomorphological map (1:7,500 scale) was obtained through an integrated approach that incorporates geological-geomorphological field mapping and geomorphological profile drawing, supported by air-photo interpretation and GIS analysis. The main purpose of the work is to describe a geomorphological approach for representing and mapping the evidence of several debris flows and landslides recognized in the framework of seismic microzonation (SM) activities. Finally, in order to elevate geomorphological maps into effective tools for land management and risk reduction, it could provide a scientific and methodological basis to demonstrate that accurate mapping provides important information, readily available for local administrations and decision-makers, for the implementation of sustainable territorial planning and loss-reduction measures.
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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.
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Rampart craters are typical impact structures of Mars and are characterized by fluidized or lobate ejecta blankets. Such structures may result from impact processes interacting with volatiles in the ...crust and/or with the atmosphere. Determining the age of their formation, therefore, is potentially important for understanding the evolutionary histories of the hydrosphere and atmosphere of the planet. In this study, we analyzed the morphological characteristics of a large, relatively well-preserved rampart crater (rim-to-rim diameter 6.5 × 6.4 km) located in Thaumasia Planum within the equatorial region of Mars. The counting of small impact craters on its ejecta blanket and the construction of crater size-frequency distribution (CSFD) allow absolute dating of this structure and identification of multiple resurfacing events. The dating was achieved by analyzing only primary impact craters; secondary impact craters (SICs) and fragmented single impactor craters (FSICs), instead, were identified and discarded on the basis of their morphological characteristics and distributions. In order not to alter the counting area, a revised approach using the Voronoï tessellation was carried out to define the surfaces relative to SICs/FSICs. This approach enables more precise age estimation in crater counting. We find that determined ages for younger events such as those of post-impact resurfacing are significantly different between two approaches of 1) counting only primary craters and utilizing the Voronoï tessellation and 2) counting primary craters + SICs/FSICs and no Voronoï tessellation. Based on the approach 1), this large rampart impact structure is determined to have formed in the Late Noachian (3.86 Ga −3.6+0.11), while three post-impact resurfacing events apparently occurred during the Amazonian (1.63 Ga −0.66+0.66, 736 Ma −130+130, 276 Ma −12+12). To verify the proposed approach, a second rampart crater in the NW sector of Thaumasia Planum was analyzed with this procedure. The absolute dating showed an impact structure always formed in the Late Noachian (3.79 Ga −3.6+0.11), with two major resurfacing events in the Amazonian (2.48 Ga −1.0+0.72, 176 Ma −11+11).
•Absolute dating of large rampart craters in the equatorial region of Mars.•Construction of a proper crater size-frequency distribution considering only primary impact craters.•Utilization of Voronoi tessellation for the removal of secondary impact craters.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Viscoplastic behavior of jointed rock masses still represents a main research topic due to the reduced possibilities of carrying on long-term tests on site as well as to the reduced ...representativeness of laboratory samples if compared to the scale of the study-case. Rock masses are often involved in creep processes as in the case of gravity-induced deformations affecting relevant portions of natural slopes. These processes can interact with main infrastructures, among which dams, pipelines, aqueducts, tunnels, highways and railways.
This study is focused on laboratory tests performed to deduce the rheological behavior of a rock masses at a reduced scale for defining the influence of joint attitude and properties on viscoplasticity. A physics of reduction scaling of mechanical behavior (down-scaling) was preliminary applied to select the most adapt material for laboratory tests; the obtained results were then reported to the effective slope scale (up-scaling).
The tested specimens were realized by an artificial moisture whose mechanical properties were scaled respect to limestones outcropping in a mountain ridge involved in already documented gravity-induced slope deformation that caused an intense rock mass jointing.
Viscoplasticity was analyzed based on uniaxial compressive strength (UCS) and creep tests. The test results were then up-scaled according to an “equivalent continuum approach” and an equivalent viscosity for the outcropping rock mass was derived. The following performed up-scaling is representative for a creep process acting over a time interval of about 200 years.
The obtained viscosity values for the equivalent rock range from 4.23·1018 up to 1.56·1019 Pa∙s and are in good agreement with the values derived by back-analysis through stress-strain numerical modeling of the gravity-induced slope deformation involving Mt. Rocchetta. The obtained results demonstrate that properties of pervasive joints are not negligible on rock mass creep acting at slope scale which can drive gravity-induced processes toward paroxysmal failures.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
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