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In recent decades, the increasing number and severity of wildfires have become a major concern in many regions of the world. Besides having direct consequences for forests, crops, and settlements, wildfires can have significant effects on the catchment's hydrology, altering their response to rainfall and promoting enhanced runoff and erosion. Increased runoff in burnt areas can result in catastrophic damage and loss of life from destructive debris flows and floods. Although observed in many regions of the world, post-wildfire debris flows/floods seem to prevail in the western USA and southern Europe. In Italy, post-wildfire debris flows/floods have been observed in a number of sectors of the Apennine range, and a total of 113 events occurred between 2001 and 2021 in the Campania region. A recent event occurred on August 24, 2020, in the Fosso delle Pescine catchment, on the southwestern slope of Mt. Omo in the L'Aquila municipality, hit by a severe wildfire at the beginning of the month. The consequences of the event on people and properties indicate the need for an evaluation of debris flow/flood hazard in both pre- and post-wildfire conditions. The analysis of these events may often be complex, requiring time and many input data. In this context, a simplified method of analysis which accounts for event initiation and propagation through a shallow water equation-based approach would represent a new and innovative solution for fast and preliminary debris flow/flood analyses. In this research, a reduced complexity analysis based on probability analysis of rainfall and 2D hydrodynamic modeling was carried out by estimating (i) wildfire extent and severity, (ii) sediment characteristics and availability, (iii) potential runoff induced by rainfall, and (iv) inundation by debris flow/flood. A debris flow/flood hazard model was developed on the basis of multiple return periods (10, 50, 100, and 300 years) for debris flow inundation scenarios derived by non-Newtonian 2D hydrodynamic modeling of debris flow hydrograph and qualitatively validated on the basis of the extent of alluvial fan deposits. Potential drawbacks of the model are related to the possible overestimation of surface runoff, related to the consideration of the whole catchment contributing area, and the limited volumetric sediment budget available at the headwater, which might not sustain a high return period event generation. A debris flow/flood event might originate from rainfall concentrated at the headwater of the catchment. [ABSTRACT FROM AUTHOR]

This paper focuses on the back analysis of an ancient, catastrophic rock avalanche located in the small city of Lettopalena (Chieti, Italy). The integrated use of various investigation methods was employed for landslide analysis, including the use of traditional manual surveys and remote sensing (RS) mapping for the identification of geological structures. The outputs of the manual and RS surveys were then utilised to numerically model the landslide using a 2D distinct element method. A series of numerical simulations were undertaken to perform a sensitivity analysis to investigate the uncertainty of discontinuity properties on the slope stability analysis and provide further insight into the landslide failure mechanism. Both numerical modelling and field investigations indicate that the landslide was controlled by translational sliding along a folded bedding plane, with toe removal because of river erosion. This generated daylighting of the bedding plane, creating kinematic freedom for the landslide. The formation of lateral and rear release surfaces was influenced by the orientation of the discrete fracture network. Due to the presence of an anticline, the landslide region was constrained in the middle-lower section of the slope, where the higher inclination of the bedding plane was detected. The landslide is characterized by a step-path slip surface at the toe of the slope, which was observed both in the modelling and the field. This paper highlights the combined use of a geological model and numerical modelling to provide an improved understanding of the origin and development of rock avalanches under the influence of river erosion, anticline structures, and related faults and fractures. [ABSTRACT FROM AUTHOR]

Rocky coastlines are characterised by steep cliffs, which frequently experience a variety of natural processes that often exhibit intricate interdependencies, such as rainfall, ice and water run-off, and marine actions. The advent of high temporal and spatial resolution data, that can be acquired through remote sensing and geomatics techniques, has facilitated the safe exploration of otherwise inaccessible areas. The datasets that can be gathered from these techniques, typically combined with data from fieldwork, can subsequently undergo analyses employing/applying machine learning algorithms and/or numerical modeling, in order to identify/discern the predominant influencing factors affecting cliff top erosion. This study focuses on a specific case situated at the Conero promontory of the Adriatic Sea in the Marche region. The research methodology entails several steps. Initially, the morphological, geological and geomechanical characteristics of the areas were determined through unmanned aerial vehicle (UAV) and conventional geological/geomechanical surveys. Subsequently, cliff top retreat was determined within a GIS environment by comparing orthophotos taken in 1978 and 2022 using the DSAS tool (Digital Shoreline Analysis System), highlighting cliff top retreat up to 50 m in some sectors. Further analysis was conducted via the use of two Machine Learning (ML) algorithms, namely Random Forest (RF) and eXtreme Gradient Boosting (XGB). The Mean Decrease in Impurity (MDI) methodology was employed to assess the significance of each factor. Both algorithms yielded congruent results, emphasising that cliff top erosion rates are primarily influenced by slope height. Finally, a validation of the ML algorithm results was conducted using 2D Limit Equilibrium Method (LEM) codes. Ten sections extracted from the sector experiencing the most substantial cliff top retreat, as identified by DSAS, were utilised for 2D LEM analysis. Factor of Safety (FS) values were identified and compared with the cliff height of each section. The results from the 2D LEM analyses corroborated the outputs of the ML algorithms, showing a strong correlation between the slope instability and slope height (R2 of 0.84), with FS decreasing with slope height. [ABSTRACT FROM AUTHOR]

Engineering rock mass classification is usually the first stage in the analysis and characterization of rock slopes. However, when dealing with sedimentary/heterogeneous rock masses, the use of existing classification methods can be difficult and often misleading, especially when used to define rockfall risk areas and appropriate slope mitigation works. In this research, we describe a novel approach for geomechanical rock slope analysis based on the combined use of remote sensing, geographic information systems (GIS), and the Slope Mass Rating (SMR) classification system. The Montagna dei Fiori area (Italian central Apennines), which is characterized by the sedimentary rocks of the Umbria Marche heterogeneous succession, is used as a case study to demonstrate the application of the proposed approach. Conventional geomechanical scanlines are integrated with photogrammetric techniques to increase the amount of data collected, especially in inaccessible areas. In particular, a new fast and low-cost method of georeferencing 3D photogrammetric models is presented. GIS are used to manage all the data acquired using remote sensing techniques and geomechanical analyses, and a semi-automatic tool developed to allow calculation of the SMR along a major highway, the SP52, which crosses the study area. Finally, a modification of the SMR procedure is proposed to enable definition of the most appropriate mitigation works in folded heterogeneous sedimentary rock masses comprising alternating marls and limestones. [ABSTRACT FROM AUTHOR]

The distribution of joints, veins and shear fractures in the Montagna dei Fiori overturned anticline is here reported. Two joint sets, longitudinal and transverse to the NNW–SSE anticline axial trend, and a conjugate system of shear fractures, are recognized. The transverse and longitudinal joint sets have a pre-folding development likely related to the foreland/foredeep flexure. The transverse joints were reopened during layer-parallel shortening along with the development of the shear fractures. Then, during syn-folding outer-arc extension and hinge-line culmination fold-axial parallel extension, both the longitudinal and transverse joints were enhanced and reactivated, respectively. [ABSTRACT FROM AUTHOR]

Landslides of the lateral spreading type, involving brittle geological units overlying ductile terrains, are a common occurrence in the sandstone and limestone plateaux of the northern Apennines of Italy. The edges of these plateaux are often the location of rapid landslide phenomena, such as rock slides, rock falls and topples. In this paper, we present a back analysis of a recent landslide (February 2014), involving the north-eastern sector of the San Leo rock slab (northern Apennines, Emilia-Romagna Region) which is a representative example of this type of phenomena. The aquifer hosted in the fractured slab, due to its relatively higher secondary permeability in comparison to the lower clayey units leads to the development of perennial and ephemeral springs at the contact between the two units. The related piping erosion phenomena, together with slope processes in the clay-shales have led to the progressive undermining of the slab, eventually predisposing large-scale landslides. Stability analyses were conducted coupling terrestrial laser scanning (TLS) and distinct element methods (DEMs). TLS point clouds were analysed to determine the pre- and post-failure geometry, the extension of the detachment area and the joint network characteristics. The block dimensions in the landslide deposit were mapped and used to infer the spacing of the discontinuities for insertion into the numerical model. Three-dimensional distinct element simulations were conducted, with and without undermining of the rock slab. The analyses allowed an assessment of the role of the undermining, together with the presence of an almost vertical joint set, striking sub-parallel to the cliff orientation, on the development of the slope instability processes. Based on the TLS and on the numerical simulation results, an interpretation of the landslide mechanism is proposed. [ABSTRACT FROM AUTHOR]

The “San Michele Arcangelo” historic trail (Aurunci Regional Park, central Italy), located along the southern slope of Mt. Altino, which is highly prone to rockfalls, is hiked every year by thousands of faithful on pilgrimage who are exposed to such kinds of instabilities. To contribute to a better understanding of the condition and evolution of such phenomena, providing a susceptibility scenario able to support the adoption of mitigation measures, a specific analysis was completed based on field and literature data. Three-dimensional virtual outcrop models were obtained through both photogrammetric and iPad Pro LiDAR surveys to derive geomechanical features of outcropping rocks and estimate potential detaching block volume. Possible mechanisms of detachment were then analyzed using the Markland test method. Susceptibility to rockfall propagation and block deposition was analyzed using GIS processing and rockfall propagation simulations based on deterministic/stochastic models. Such models consist of a combination of a deterministic algorithm able to simulate the physics of rockfall movement during propagation and a stochastic treatment of input parameters based on random sampling within defined interval. Two different rockfall simulations were compared in this study using the Rockyfor3D™ (ecorisQ Association) software and the newly developed RocFall3© (RocScience) code. The use of iPad Pro LiDAR survey provides accurate and high-resolution point clouds, with high speed of acquisition and real-time processing of data. Discontinuity sets identified from 3D models have represented the input for kinematic analyses of slopes, allowing to identify potential failure mechanisms among wedge and planar sliding or toppling. Rockfall simulations indicate the potential for rock blocks propagation and deposition over the whole study area. Comparing the results of rockfall simulations with the geomorphological map of the area it is evident the control exerted by the hydrographic network on rockfall propagation as demonstrated by the presence of screes and slope deposits along the main channels. Understanding the potential susceptibility to both propagation and deposition of rock blocks along the trail provides useful indication for the assessment of appropriate mitigation measures to realize for the safer touristic fruition of the site. [ABSTRACT FROM AUTHOR]

In this research, we present a new approach to define the distribution of block volumes during rockfall simulations. Unmanned aerial vehicles (UAVs) are utilized to generate high-accuracy 3D models of the inaccessible SW flank of the Mount Rava (Italy), to provide improved definition of data gathered from conventional geomechanical surveys and to also denote important changes in the fracture intensity. These changes are likely related to the variation of the bedding thickness and to the presence of fracture corridors in fault damage zones in some areas of the slope. The dataset obtained integrating UAV and conventional surveys is then utilized to create and validate two accurate 3D discrete fracture network models, representative of high and low fracture intensity areas, respectively. From these, the ranges of block volumes characterizing the in situ rock mass are extracted, providing important input for rockfall simulations. Initially, rockfall simulations were performed assuming a uniform block volume variation for each release cell. However, subsequent simulations used a more realistic nonuniform distribution of block volumes, based on the relative block volume frequency extracted from discrete fracture network (DFN) models. The results of the simulations were validated against recent rockfall events and show that it is possible to integrate into rockfall simulations a more realistic relative frequency distribution of block volumes using the results of DFN analyses. [ABSTRACT FROM AUTHOR]

This research aims to highlight the importance of adopting a multi-disciplinary approach to understanding the factors controlling large rock avalanches using the Scanno landslide, Italy, as a case study. The study area is the Mount Genzana, Abruzzi Central Apennines, characterized by the regional Difesa-Mount Genzana-Vallone delle Masserie fault zone. The Scanno landslide is famous for its role in the formation of the Scanno Lake. The landslide is characterized by a wide exposed scar, which was interpreted in previous studies as the intersection of high-angle joints and an outcropping bedding plane on which the landslide failed sometime between the Upper Pleistocene and the Holocene. In this study, the Scanno landslide was investigated through the integration of geological, geomechanical and geomorphological surveys. Remote sensing techniques were used to enrich the conventionally gathered datasets, while Geographic Information Systems (GIS) were used to integrate, manage and investigate the data. The results of the authors investigation show that the outcropping landslide scar can be interpreted as a low-angle fault, associated with the Difesa-Mount Genzana-Vallone delle Masserie fault zone, which differs from previous investigations and interpretations of the area. The low-angle fault provides the basal failure surface of the landslide, with two systematic high-angle joint sets acting as lateral release and back scarp surfaces, respectively. In light of these new findings, pre- and post-failure models of the area have been created. The models were generated in GIS by combining LiDAR (Light Detection and Ranging) and geophysics data acquired on the landslide body and through bathymetric survey data of the Scanno Lake. Using the pre- and post-failure models it was possible to estimate the approximate volume of the landslide. Finally, back-analyses using static and dynamic limit equilibrium methods is also used to show the possible influence of medium-to-high magnitude seismic events in triggering the Scanno landslide. [ABSTRACT FROM AUTHOR]

Digital photogrammetry (DP) represents one of the most used survey techniques in engineering geology. The availability of new high-resolution digital cameras and photogrammetry software has led to a step-change increase in the quality of engineering and structural geological data that can be collected. In particular, the introduction of the structure from motion methodology has led to a significant increase in the routine uses of photogrammetry in geological and engineering geological practice, making this method of survey easier and more attractive. Using structure from motion methods, the creation of photogrammetric 3D models is now easier and faster, however the use of ground control points to scale/geo-reference the models are still required. This often leads to the necessity of using total stations or Global Positioning System (GPS) for the acquisition of ground control points. Although the integrated use of digital photogrammetry and total station/GPS is now common practice, it is clear that this may not always be practical or economically convenient due to the increase in cost of the survey. To address these issues, this research proposes a new method of utilizing photogrammetry for the creation of georeferenced and scaled 3D models not requiring the use of total stations and GPS. The method is based on the use of an object of known geometry located on the outcrop during the survey. Targets located on such objects are used as ground control points and their coordinates are calculated using a simple geological compass and trigonometric formula or CAD 3D software. We present three different levels of survey using (i) a calibrated digital camera, (ii) a non-calibrated digital camera and (iii) two commercial smartphones. The data obtained using the proposed approach and the three levels of survey methods have been validated against a laser scanning (LS) point cloud. Through this validation we highlight the advantages and limitations of the proposed method, suggesting potential applications in engineering geology. [ABSTRACT FROM AUTHOR]

The characterization of landslides located in remote areas poses significant challenges due to the costs of reaching the sites and the lack of reliable subsurface data to constrain geological interpretations. In this paper, the advantages of combining field and remote sensing techniques to investigate the deformation and stability of rock slopes are demonstrated. The characterization of the Fels landslide, a large, slowly deforming rock slope in central Alaska, is described. Historical aerial imagery is used to highlight the relationship between glacier retreat and developing instability. Airborne laser scanning (ALS) and Structure-from-Motion (SfM) datasets are used to investigate the structural geological setting of the landslide, revealing a good agreement between structural discontinuities at the outcrop and slope scales. The magnitude, plunge, and direction of slope surface displacements and their changes over time are studied using a multi-temporal synthetic aperture radar speckle-tracking (SAR ST) dataset. The analyses show an increase in displacement rates (i.e., an acceleration of the movement) between 2010 and 2020. Significant spatial variations of displacement direction and plunge are noted and correlated with the morphology of the failure surface reconstructed using the vector inclination method (VIM). In particular, steeper displacement vectors were reconstructed in the upper slope, compared to the central part, thus suggesting a change in basal surface morphology, which is largely controlled by rock mass foliation. Through this analytical approach, the Fels landslide is shown to be a slow-moving, compound rockslide, the displacement of which is controlled by structural geological features and promoted by glacier retreat. [ABSTRACT FROM AUTHOR]

Italy is famous for its one-of-a-kind landscapes and the many cultural heritage sites characterizing the story of its regions. In central Italy, during the medieval age, some of them were built on the top of high and steep cliffs, often on the top of ancient ruins, to protect urban agglomerations, goods and people. The geographical locations of these centers allowed them to maintain their original conformation over time, but, at the same time, exposed them to a high risk of landslides. In this context, this research aimed to present an integrated and low-cost approach to study the potential landslide phenomena affecting two medieval towns. Field surveys and mapping were carried out through the use of innovative digital mapping tools to create a digital database directly on the field. Data gathered during field surveys were integrated with GIS analyses for an improved interpretation of the geological and geomorphological features. Due to the inaccessibility of the cliffs surrounding the two villages, a more detailed analysis of these areas was performed through the use of unmanned aerial vehicle-based photogrammetry, while advanced differential synthetic aperture radar interferometry (A-DInSAR) interpretation was undertaken to verify the stability of the buildings in proximity to the cliffs and other potential active failures. The results of the study highlighted the similar geometry and structural settings of the two areas. Kinematically, the intersection of three main joint sets tends to detach blocks (sometimes in high volumes) from the cliffs. The A-DInSAR analysis demonstrated the presence of a landslide failure along the northwest side of the Monte San Martino town. The buildings in proximity to the cliffs did not show evidence of movements. More generally, this research gives insights into the pro and cons of different survey and analysis approaches and into the benefits of their procedural integration in space and in time. Overall, the procedure developed here may be applied in similar contexts in order to understand the structural features driving slopes' instabilities and create digital databases of geological/monitoring data. [ABSTRACT FROM AUTHOR]

The integration of multiple data sources, including satellite imagery, aerial photography, and ground-based measurements, represents an important development in the study of landslide processes. The combination of different data sources can be very important in improving our understanding of geological phenomena, especially in cases of inaccessible areas. In this context, the study of coastal areas represents a real challenge for the research community, both for the inaccessibility of coastal slopes and for the numerous drivers that can control coastal processes (subaerial, marine, or endogenic). In this work, we present a case study of the Conero Regional Park (Northern Adriatic Sea, Ancona, Italy) cliff-top retreat, characterized by Neogenic soft rocks (flysch, molasse). In particular, the study is focused in the area between the beach of Portonovo and Trave (south of Ancona), which has been studied using aerial orthophoto acquired between 1978 and 2021, Unmanned Aerial Vehicle (UAV) photographs (and extracted photogrammetric model) surveyed in September 2021 and 2012 LiDAR data. Aerial orthophotos were analyzed through the United States Geological Survey's (USGS) tool Digital Shoreline Analysis System (DSAS) to identify and estimate the top-cliff erosion. The results were supported by the analysis of wave data and rainfall from the correspondent period. It has been found that for the northernmost sector (Trave), in the examined period of 40 years, an erosion up to 40 m occurred. Furthermore, a Digital Elevation Model (DEM) of Difference (DoD) between a 2012 Digital Terrain Model (DTM) and a UAV Digital Surface Model (DSM) was implemented to corroborate the DSAS results, revealing a good agreement between the retreat areas, identified by DSAS, and the section of coast characterized by a high value of DoD. [ABSTRACT FROM AUTHOR]

The mechanisms controlling the onset of minor slope instability at the edges of rocky plateaux exhibiting lateral spreading phenomena are yet to be fully understood. Hypotheses have recently been introduced to explain the influence of groundwater within these plateaux on geomorphological processes leading to slope instability. We present a back analysis of a recent landslide which occurred on 27th February 2014 in the town of San Leo, Italy. The role of the softening of basal clay shales and erosion due to seepage is investigated using finite element geomechanical models. Both processes were observed in the field and are related to groundwater discharging along the contact between the rocky slab and the clay-rich substratum. Fracture propagation paths involving pre-existing discontinuities and intact rock bridges failure were simulated using a simplified discrete fracture network (DFN) model coupled with a Voronoi polygonal mesh approach. Model results allow the failure to be classified as a secondary toppling phenomenon. Moreover, a critical amount of undermining was indicated by the models agreeing with field observations made prior to the failure. Based on the modelling results, an interpretation of the overall mechanism inducing failures at the edges of fractured rock slabs is given. In particular, the inter-relationships between groundwater flow and geomorphic processes acting within the rock masses are presented. [ABSTRACT FROM AUTHOR]

The stability of a rock slope is strongly influenced by the pattern of groundwater flow through the fracture system, which may lead to an increase in the water pressure in partly open joints and the consequent decrease in the rock wall strength. The comprehension of the fracture pattern is a challenging but vital aspect in engineering geology since the fractures' spatial distribution, connectivity, and aperture guide both the water movement and flow quantity within the rock volume. In the literature, the most accepted methods to hydraulically characterise fractured rocks in situ are the single borehole packer test, the high-resolution flow meters for fractures, and the artificial tracer tests performed in boreholes. However, due to the high cost a borehole requires and the general absence of wells along coastal cliffs, these methods may not be appropriate in rockfall-prone areas. In this study, an unsaturated rocky cliff, strongly affected by rockfalls, was investigated by combining kinematic analysis, Discrete Fracture Network (DFN) modelling, and artificial tracer tests. The DFN model and potential rock block failure mechanisms were derived from high-resolution 3D virtual outcrop models via the Structure from Motion (SfM) photogrammetry technique. An artificial tracer was injected using a double ring infiltrometer atop the recharge zone of the slope to determine the infiltration rate and validate the DFN results. The DFN and tracer test methods are frequently used at different spatial scales and for different disciplines. However, the integration of digital photogrammetry, DFN, and tracer tests may represent a new step in rockfall and landslide studies. This approach made possible the identification of groundwater flow patterns within the fracture system and revealed about a 10-day tracer transit time from the injection area and the monitored slope, with similar conductivity values gathered from both the DFN and tracer test. Planar and wedge failures with volumes ranging from 0.1 and 1 m3 are the most probable failure mechanisms in the areas. The results were consistent with the delay between the intense rainfall and the slope failures previously documented in the study area and with their mechanisms. [ABSTRACT FROM AUTHOR]

Digital elevation models produced from COSMO-SkyMed imagery were used to delineate palaeo-drainage in a wide area surrounding the Siwa and Al-Jaghbub oases of the western Sahara Desert (Egypt and Libya). This new generation of synthetic aperture radar imagery is suitable for this purpose because of its high spatial resolution and capacity to penetrate dry surface sediments. Different techniques such as radar interferometry and radargrammetry were used to produce digital elevation models. These were assessed for accuracy and then combined to produce a single elevation model of the area. The resulting elevation model was used to support the geological study and palaeo-environmental interpretation of the area. It revealed buried features of the landscape, including inactive palaeo-drainage systems. Drainage features were extracted from the elevation model using geographical information systems; results were combined and assessed with respect to geological field data, as well as data from the literature. Previous studies in the area suggest that a wide river, probably the old Nile River, flowed into the Libyan palaeo-Sirte before the Late Messinian drawdown of the Mediterranean Sea. During the Late Messinian lowering of the sea the fluvial system changed shape and carved deep canyons throughout north-eastern Africa. The reported findings on the key Siwa area were used to precisely delineate the physiography of the modern drainage network and to confirm findings from our previous geological research in the area. [ABSTRACT FROM AUTHOR]

This paper focuses on numerical modelling and back analysis of the Hell's Mouth landslide to provide improved understanding of the evolution of a section of the north coast of Cornwall, UK. Discontinuity control is highlighted through the formation of a 'zawn' or inlet, the occurrence of two successive landslides and evidence of ongoing instability through opening of tension cracks behind the cliff top. Several integrated remote sensing (RS) techniques have been utilised for data acquisition to characterise the slope geometry, landslide features and tension crack extent and development. In view of the structural control on the rock slope failures, a 3D distinct element method (DEM) code incorporating a discrete fracture network and rigid blocks has been adopted for the stability analysis. The onset and opening of tension cracks behind the modelled slope failure zones has also been studied by analysing the displacements of two adjoining landslide blocks, between which, a joint-related tension crack developed. In addition, a sensitivity analysis has been undertaken to provide further insight into the influence of key discontinuity parameters (i.e. dip, dip direction, persistence and friction angle) on the stability of this section of the coastline. Numerical modelling and field observations indicate that block removal and preferential erosion along a fault resulted in the formation of the inlet. The development of the inlet provides daylighting conditions for discontinuities exposed on the inlet slope wall, triggering the initial landslide which occurred on 23rd September 2011. Numerical modelling, and evidence from a video of the initial landslide, suggests that the cliff instability is characterised by a combination of planar sliding, wedge sliding and toppling modes of failure controlled by the discrete fracture network geometry. [ABSTRACT FROM AUTHOR]

This paper describes the results of topographical and geological surveys carried out at the prehistoric area of Melka Kunture (Ethiopia) in order to produce new detailed maps at a scale of 1:10,000 for supporting archaeological investigations and providing good reference cartography during fieldwork. The topographic support was created from the stereorestitution of two pairs of Standard Stereo IKONOS-2, 1m pansharpened satellite imageries covering an area of about 100km2. The topographic map was utilized both for the geological survey and for the interpretation of the palaeo-environmental evolution of the site based on present geomorphological features. The aerial triangulation of satellite images, performed using ground control points measured using differential GPS surveys, allowed the stereoscopic visualization of the area and the creation of a digital elevation model and orthophotos. These results were a useful cartographic aid during the geological survey when all the outcrops along gullies, streams, roads and rivers were inspected and documented through additional in-depth field checks. The geological map was created and refined using the digital elevation model and photointerpretation of stereo and orthoimageries, making it possible to fully identify the geological boundaries between formations and recognize geomorphological features. [ABSTRACT FROM AUTHOR]

Several orogenic belts exhibit regional-scale anticlines characterized by prominent faults in their crestal/forelimb zone. These faults are also a common feature in the Neogene fold-and-thrust belt of the Apennines, where they have been contrastingly interpreted as younger-on-older thrust faults, large-scale strike-slip faults, and pre- or syn-thrusting normal faults. In this study, we analysed a NW–SE-trending fault (Montagna dei Fiori Fault) that affects the hinge-zone/forelimb of the Montagna dei Fiori Anticline. This fold is the outermost exposed contractional structure within the Pliocene–Quaternary antiformal stack of the outer Central Apennines. The integration of stratigraphic and structural data collected during a field geological survey enabled us to reconstruct a multiphase reactivation and deformation along the Montagna dei Fiori Fault. From the novel field data, a different interpretation for the evolution of the Montagna dei Fiori Fault is proposed. The fault originated as a Late Cretaceous – middle Miocene, NE-dipping, Dinaric up-thrust and was later reactivated, displaced and rotated during Pliocene Apennine thrusting and related folding, until assuming a present-day SW-dipping attitude with an apparent normal fault character. This newly proposed Dinaric origin of the Montagna dei Fiori structure is compared with an analogous subsurface example of a Palaeogene–Quaternary structure imaged by seismic reflection profile in the Adriatic foreland. The outcome of this combined field and subsurface investigation provides new elements to unravel the complex evolution of the Apennine thrust belt that developed at the expense of a previously deformed foreland, ahead of the advancing Dinaric chain. [ABSTRACT FROM AUTHOR]

This paper proposes a novel method to incorporate unfavorable orientations of discontinuities into machine learning (ML) landslide prediction by using GIS-based kinematic analysis. Discontinuities, detected from photogrammetric and aerial LiDAR surveys, were included in the assessment of potential rock slope instability through GIS-based kinematic analysis. Results from the kinematic analysis, coupled with several commonly used landslide influencing factors, were adopted as input variables in ML models to predict landslides. In this paper, various ML models, such as random forest (RF), support vector machine (SVM), multilayer perceptron (MLP) and deep learning neural network (DLNN) models were evaluated. Results of two validation methods (confusion matrix and ROC curve) show that the involvement of discontinuity-related variables significantly improved the landslide predictive capability of these four models. Their addition demonstrated a minimum of 6% and 4% increase in the overall prediction accuracy and the area under curve (AUC), respectively. In addition, frequency ratio (FR) analysis showed good consistency between landslide probability that was characterized by FR values and discontinuity-related variables, indicating a high correlation. Both results of model validation and FR analysis highlight that inclusion of discontinuities into ML models can improve landslide prediction accuracy. [ABSTRACT FROM AUTHOR]

Abstract Understanding the impact of data uncertainty is a fundamental part of ensuring safe design of manmade excavations. Although good levels of knowledge are achievable from field investigations and experience, a natural geological environment is subject to intrinsic variability that may compromise the correct prediction of the system response to the perturbations caused by mining, with direct consequences for the stability and safety of the operations. Different types of geoscientific evidence, including geological, geomorphic, geotechnical, geomatics, and geophysical data have been used to develop and perform two-dimensional Limit Equilibrium and Finite Element Method stability analyses of a lignite open-pit mine in North Bohemia (Czech Republic) affected by recent landslides. A deterministic-probabilistic approach was adopted to investigate the effect of uncertainty of the input parameters on model response. The key factors affecting the system response were identified by specific Limit Equilibrium sensitivity analyses and studied in further detail by Finite Element probabilistic analyses and the results were compared. The work highlights that complementary use of both approaches can be recommended for routine checks of model response and interpretation of the associated results. Such an approach allows a reduction of system uncertainty and provides an improved understanding of the landslides under study. Importantly, two separate failure mechanisms have been identified from the analyses performed and verified through comparisons with inclinometer data and field observations. The results confirm that the water table level and material input parameters have the greatest influence on the stability of the slope. Highlights • We performed stability analyses of an open pit mine affected by landslide activity. • Two-dimensional Limit Equilibrium and Finite Element Method analyses were used. • Effect of input parameters uncertainty was evaluated through a probabilistic approach. • Two separate failure mechanisms were identified from the analyses performed. • Results were in good agreement with inclinometer data and field observations. [ABSTRACT FROM AUTHOR]

Accurate slope stability analysis is essential for human activity in high-risk geological contexts. This may, however, not be enough in the case of quarrying where the dynamic and evolving environment also requires effective monitoring. A well-designed monitoring system requires the acquisition of a huge dataset over time, improving knowledge of the study area and helping to refine prediction from stability analysis. This paper reports the implementation of an integrated monitoring system in a marble quarry in the Apuan Alps (Italy) and some of the results obtained. The equipment consists of a traditional geotechnical monitoring system (extensometers, crackmeters and clinometers) and two modern topographic monitoring systems (a terrestrial interferometer and a robotic total station). This work aims to provide in-depth knowledge of the large scale rock mass behaviour as a result of marble exploitation, thereby allowing continuous excavation. The results highlight the importance of integrating different monitoring systems. [ABSTRACT FROM AUTHOR]

We present a workflow for investigating large, slow-moving landslides which combines the synthetic aperture radar (SAR) technique, GIS post-processing, and airborne laser scanning (ALS), and apply it to Fels landslide in Alaska, US. First, we exploit a speckle tracking (ST) approach to derive the easting, northing, and vertical components of the displacement vectors across the rock slope for two five-year windows, 2010–2015 and 2015–2020. Then, we perform post-processing in a GIS environment to derive displacement magnitude, trend, and plunge maps of the landslide area. Finally, we compare the ST-derived displacement data with structural lineament maps and profiles extracted from the ALS dataset. Relying on remotely sensed data, we estimate that the thickness of the slide mass is more than 100 m and displacements occur through a combination of slumping at the toe and planar sliding in the central and upper slope. Our approach provides information and interpretations that can assist in optimizing and planning fieldwork activities and site investigations at landslides in remote locations. [ABSTRACT FROM AUTHOR]

Gully head erosion causes serious land degradation in semiarid regions. The existing studies on gully head erosion are mainly based on measuring the gully volume in small-scale catchments, which is a labor-intensive and time-consuming approach. Therefore, it is necessary to explore an accurate method quantitatively over large areas and long periods. The objective of this study was to develop a model to assess gully head erosion in the Loess Plateau of China using a method based on the SBAS-InSAR technique. The gully heads were extracted from the digital elevation model and validated by field investigation and aerial images. The surface deformation was estimated with SBAS-InSAR and 22 descending ALOS PALSAR datasets from 2007 to 2011. A gully head erosion model was developed; this model can incorporate terrain factors and soil types, as well as provides erosion rate predictions consistent with the SBAS-InSAR measurements (R2 = 0.889). The results show that gully head erosion significantly depends on the slope angle above the gully head, slope length, topographic wetness index, and catchment area. The relationship between these factors and the gully head erosion rate is a power function, and the average rate of gully head erosion is 7.5 m3/m2/year, indicating the high erosional vulnerability of the area. The accuracy of the model can be further improved by considering other factors, such as the stream power factor, curvature, and slope aspect. This study indicates that the erosion rate of gully heads is almost unaffected by soil type in the research area. An advantage of this model is that the gully head area and surface deformation can be easily extracted and measured from satellite images, which is effective for assessing gully head erosion at a large scale in combination with SBAS-InSAR results and terrain attributes. [ABSTRACT FROM AUTHOR]

An increasing number of satellite platforms provide daily images of the Earth's surface that can be used in quantitative monitoring applications. However, their cost and the need for specific processing software make such products not often suitable for rapid mapping and deformation tracking. Google Earth images have been used in a number of mapping applications and, due to their free and rapid accessibility, they have contributed to partially overcome this issue. However, their potential in Earth's surface displacement tracking has not yet been explored. In this paper, that aspect is analyzed providing a specific procedure and related MATLAB™ code to derive displacement field maps using digital image correlation of successive Google Earth images. The suitability of the procedure and the potential of such images are demonstrated here through their application to two relevant case histories, namely the Slumgullion landslide in Colorado and the Miage debris-covered glacier in Italy. Result validation suggests the effectiveness of the proposed procedure in deriving Earth's surface displacement data from Google Earth images. [ABSTRACT FROM AUTHOR]

In recent years data acquisition from remote sensing has become readily available to the quarry sector. This study demonstrates how such data may be used to evaluate and back analyse rockfall potential of a legacy slope in a blocky rock mass. Use of data obtained from several aerial LiDAR (Light Detection and Ranging) and photogrammetric campaigns taken over a number of years (2011 to date) provides evidence for potential rockfall evolution from a slope within an active quarry operation in Cornwall, UK. Further investigation, through analysis of point cloud data obtained from terrestrial laser scanning, was undertaken to characterise the orientation of discontinuities present within the rock slope. Aerial and terrestrial LiDAR data were subsequently used for kinematic analysis, production of surface topography models and rockfall trajectory analyses using both 2D and 3D numerical simulations. The results of an Unmanned Aerial Vehicle (UAV)-based 3D photogrammetric analysis enabled the reconstruction of high resolution topography, allowing one to not only determine geometrical properties of the slope surface and geo-mechanical characterisation but provide data for validation of numerical simulations. The analysis undertaken shows the effectiveness of the existing rockfall barrier, while demonstrating how photogrammetric data can be used to inform back analyses of the underlying failure mechanism and investigate potential runout. [ABSTRACT FROM AUTHOR]