1,721,231 research outputs found
Landslides and climate change.
No full textClimate change refers to a statistically significant variation in either the mean state of the climate or in its variability, persisting for an extended period, typically decades or longer. Climate change on Earth may be due to natural internal processes or external forcing, or to persistent anthropogenic perturbation of the composition of the atmosphere or of land use. The Fourth Assessment Report of the Intergovernmental Panel on Climate Change states that the warming of the climate system is unequivocal. Moreover, there is a high level of confidence that this warming is a result of human activities releasing greenhouse gases to the atmosphere from the burning of fossil fuels, deforestation and agricultural activities. A range of future greenhouse gas emission scenarios are also presented, based on estimates of economic growth, technological development and international cooperation. In all scenarios temperatures continue to rise worldwide, with global mean temperatures averaging plus 2 to 4 °C by the end of the century, accompanied by changes in the amounts and patterns of precipitation. The predicted rate of warming seems to be faster than ever recorded and in particular over the last 2000 years, and also since the Earth was exiting the Little Ice Age. There will also be an increase in the frequency and intensity of extreme temperature and precipitation events at any time of the year, regardless of the season.
If the evidence of climate change is unequivocal, is climate change triggering more landslides, or will it in the future? Intuitively, yes: climate changes have the potential to modify the stability of slopes, both natural and constructed. This issue is important and urgent, no matter what are the actual causes of climate changes. It has been proved that most landslides are caused by saturated soil moisture conditions and by loss in soil strength, triggered by climatically-controlled processes, such as intense and/or prolonged precipitation events, rapid snowmelt, glacier thinning, permafrost degradation or river migration, depending on geomorphological settings. If climate change leads to increased frequency and/or magnitude of these events and processes, the frequency and/or magnitude of landslides in a region will be similarly influenced. Thus, we can expect more instability, as a consequence of the increasing number of short but intense events, as well as by increasing cumulative rainfall etc.
Although the frequency and/or magnitude of landslides may increase with the anticipated climate change, the regional distribution of landslides is not expected to change significantly, as many of the primary factors controlling landslide susceptibility, such as geology, physiography and slope, are remaining relatively constant. Potentially unstable areas, however, could for example include slopes presently underlain by degrading permafrost. A sort of domino effect may also be expected: increased landslide activity may lead to increased sediment loads and channel instability in rivers.
Currently, where the best practice in landslide risk mitigation is established, the design and management of infrastructure and urban assets affected by natural slope instability is carried out on the basis of specified standards and guidelines that assume static environmental conditions. However, the rate of dominant input parameters (i.e., precipitation and temperature) is now clearly changing. Hence, a review of this approach is demanded, as the assumption of a steady climate state can be misleading.
However, such impacts are currently speculative and will be difficult to unravel from “pure” anthropogenic effects, in some case driven by climate changes themselves. Accordingly, compound effects of climate change and other human actions (where humans are both co-triggers and element at risk) must be accounted for. In this sense, some studies seem to highlight the fact that climate change is important, but land use change is even mor..
How rock block shape can influence the kinematics and direction of slope displacement: Results from the San Leo rock plateau, Italy
No full textThe kinematic behavior of slope failures in fractured rock masses is strongly influenced by the presence of discontinuities. Block size and shape are controlled by fracture orientation, intensity and length. A preliminary analysis of these parameters was conducted in the north-eastern cliff of the San Leo plateau (Italy). Classical stereographic projection analysis, coupled with GIS, and a limit equilibrium approach were applied to analyze the blocks shape and the block kinematic constraint and thereby define the expected movement directions of selected rock wedges. Our analyses provided further insights into the instability mechanisms involving the sub-vertical cliff faces. The data are also useful in the interpretation of the data collected by the slope monitoring system. By deriving the expected direction of movements, its effectiveness can be improved. The size distribution and the shape of the blocks in the landslide deposit were mapped and classified, providing the constraint for more advanced geomechanical analyses
Geological Hazards and Cultural Heritage: the 2014 San Leo Landslide (Northern Apennines, Italy) and Its Implications
No full textTen years ago, on 27 February 2014, the town of San Leo, in the Emilia-Romagna region of Italy, experienced a tragic landslide event that captured both national and international attention. Perched atop a towering limestone cliff, San Leo is renowned not only for its impressive medieval fortress and rich cultural heritage, but also for its geologically unstable location. The landslide, which saw a significant portion of the north-eastern rocky cliff face collapse, emphasised the inherent vulnerability of communities living in spectacular yet hazardous environments. The lessons learned from San Leo experience provide a roadmap for other heritage sites facing similar geological hazards, ensuring that their irreplaceable cultural assets are safeguarded for future generations
Esempi di interventi strutturali di mitigazione del rischio da frana nell’Appennino centro-settentrionale
No full textL’area di studio corrisponde al settore appenninico delle province emiliane, ove affiorano formazioni geologiche rientranti nelle cosiddette “rocce deboli”, litologicamente e strutturalmente complesse, entro le quali i movimenti di versante più diffusi corrispondono a frane dallo stile di attività complesso, del tipo scivolamenti roto-traslativi associati a colamenti di terra superficiali. Lo scopo del lavoro è di dare opportuna visibilità ai numerosi interventi di mitigazione del rischio da frana eseguiti dagli enti pubblici che operano sul territorio, in molti casi redatti e concordati con i ricercatori universitari partecipanti al progetto
Analysis of the interaction between buried pipelines for the transport of fluids and landslides
No full textThe aim of this work is the study of the factors that influence the interaction between buried pipelines for the transport of fluids, e.g. gas and water, and Permanent Ground Deformation (PGD), in particular landslides. Pipelines have a fundamental role both in normal operating conditions and in emergency situations. Eventual leakage of the fluids caused by structural damage could cause environmental disasters, financial costs and abuses of resources. In the present work, the methodology proposed by Suresh et al. (2007) was adopted for the calculation of the structural deformation due to the landslide. Furthermore, sensitivity analysis permitted to highlight the influence of different factors, e.g. The pipelines diameter, on the value of the deformation due to their interaction with landslide. The study was applied in different areas of the northern Apennines, selected as representative of the landslide phenomena occurring in Emilia-Romagna region
Modelling groundwater and slope processes in a calcarenitic slab: The case of San Leo (northern Apennines)
No full textvv
Geological and numerical models as a tool to manage landslide risk: The Passo della Morte case study (UD, Italy)
No full textIn the northern Italian Alps, along the Tagliamento River valley (46°23'49" N, 12°42'51" E), a large deep-seated landslide affects a road tunnel near "Passo della Morte", along National Road 52 "Carnica". Several secondary phenomena are developing on the unstable slope, as rock block slides and shallow debris slides. This work focuses on the creation of a geological and numerical model able to simulate the displacements of two adjacent and partly superimposed shallow landslides, which are damaging the east entrance of the tunnel. In fact, field surveys and long-term monitoring allowed the geometries and the kinematics of the landslide bodies to be defined with great detail. In this phase, a numerical model is needed in order to evaluate the effectiveness of possible structural mitigation works. The complexity of the landslides dynamics and the different rates of activity suggest to set up a 3D model rather than a 2D one, using the commercial software FLAC3D. A helicopter-borne Light Detection And Ranging (LiDAR) survey allowed to rely on a 1 m Digital Terrain Model (DTM) for surface topography, while several boreholes equipped with inclinometers supported the definition of a 3D sliding surface. However, the high resolution of the input data collides with the necessity of reduce computational time to an acceptable level, thus an interpolation of the spatial data was almost compulsory. Anyhow, the calibrated model of the "Passo della Morte" landslides, obtained with filtered data, is the starting point for the simulation of different types of possible countermeasure works designed to mitigate landslide risk
Is higher resolution always better? A comparison of open-access DEMs for optimized slope unit delineation and regional landslide prediction
Full text linkDigital elevation models (DEMs) play a key role in slope instability studies, ranging from landslide detection and recognition to landslide prediction. DEMs assist these investigations by reproducing landscape morphological features and deriving relevant predisposing factors, such as slope gradient, roughness, aspect, and curvature. Additionally, DEMs are useful for delineating map units with homogeneous morphological characteristics, such as slope units (SUs).In many cases, the selection of a DEM depends on factors like accessibility and resolution, without considering its actual accuracy. In this study, we compared freely available global elevation models (Advanced Land Observing Satellite (ALOS) World 3D-30m, Copernicus GLO-30 (COP), Forest And Buildings removed COP DEM (FABDEM)) and a national dataset (TINITALY) with a reference model (local airborne lidar) to identify the most suitable DEM for representing fine-scale morphology and delineating SUs in the Marche region, Italy, for landslide susceptibility studies. Furthermore, we proposed a novel approach for selecting the optimal SU partition.The DEM comparison was based on several criteria, including elevation, residual DEMs, roughness indices, slope variations, and the ability to delineate SUs. TINITALY, resampled at a 30mx30m pixel size, was found to be the most suitable DEM for representing fine-scale terrain morphology. It was then used to generate the optimal SU partition among 18 combinations. These combinations were evaluated using both existing and newly integrated metrics alongside mapped landslide inventories to optimize terrain delineation and contribute to landslide susceptibility studies
Landslides as proxies of climate change: evidence from past activity records in the Dolomites (Italy)
No full textThis study concerns the relationships between climate changes and hillslope evolution during the Late Quaternary, with particular attention to landslide processes. The research has been carried out in test areas located in the Dolomites (Italy), following the basic idea that modifications in landslide frequency may be interpreted as changes in the hydrological conditions of the slopes, which are in turn controlled by climate. By analysing a large data set, consisting of 75 radiocarbon dates, obtained with reference to 24 landslides, temporal clustering of dated mass movements have been observed, that is a necessary condition to look for possible causes of past activity periods. By analysing the data set, four periods of enhanced landsliding have been outlined. These four periods have been compared with different Late Glacial and Holocene paleoclimatic records, in order to check the correspondence between temporal concentrations of landslide events and climatic events. Besides the intrinsic difficulties in the correlation among these records, which are mainly due to different spatial scales (local, regional and global), to dissimilar time-resolutions and dating constraints, remarkable evidence comes forward. The periods of enhanced slope instability in the Dolomites display a quite good correlation with cold and humid phases. At the same time, also periods of dry climate have a clear influence on landslide activity, resulting in gaps in the time series. The results suggest that landslide activity could have been climatically-driven and that, in particular, a positive moisture balance could have played a major role in conditioning slope instability at the hundred to thousand years time scale
Slope Instability Processes Affecting the Pietra di Bismantova Geosite (Northern Apennines, Italy)
No full textA geomechanical and geomorphological study was carried out on a vast biocalcarenite slab which is an impressive landmark in the Reggio Emilia Apennines: the Pietra di Bismantova. This area is of great importance since it is a unique feature in the gentle hilly landscape of this portion of the Apennine range. Since the end of the last glaciation, this site has been subject to intense degradation processes affecting the rock slopes and posing serious problems regarding its preservation and the safety of visitors. The goal of this research was to identify the areas most prone to geological hazards and possible risk situations for the numerous tourists visiting this geosite. Observations and analyses have been carried out aiming at the geomechanical characterization of the rock types making up the Bismantova slab. The results have shown that the areas potentially most subject to landslides are the SE, NE and NW faces, where the rock parameters are poorest and degradation processes are particularly intense. Remedial measures should be introduced in these critical areas in order to stabilize the cliff and guarantee safe fruition to all visitors
- …
