Landslide inventory and rockfall risk assessment of the Monte Pellegrino Oriented Nature Reserve area (Sicily)

In the last 20 years the natural oriented reserve of Monte Pellegrino is affected by several rockfall events. This sector of the Northern Sicily is a strategic urban area and represent the most important element of both the religious and cultural tradition and landscape for the city of Palermo.The rockfalls are here the major natural threats and represent a relevant risk of people, structures and infrastructures and prevents the economic and social development that could be made by high tourist potential of the area. For the above mentioned reasons a detailed geological and geotechnical study in order to define a quantitative risk analysis is now being carried out, concurrently with the implementation of the landslide inventory essential for analysis and monitoring. Monte Pellegrino, located along the Alpine orogenic belt (Catalano et al., 2013) in the emerged Sicilian fold and thrust belt, is an isolated carbonate massif characterized by the presence of poor rock masses and steeply sloping hillsides. The quantitative risk analysis was performed through several steps and taking into account the provisions of directive which is in force in the local institutions. The spread of a rockfall depends on many control factors such as geological setting and geomechanical features for both source area and below area, it is therefore necessary to define different input elements: an inventory of landslides, a database of factors and a dataset that contains the results of the on-site inspections like the geostructural and geomorphological data. The archive of landslides occurred over a period of 20 years was created; the spatial database (constructed in accordance with the standards) contains information on the identification code and date of the event, location, type, involved lithology and related thematic maps. Other thematic maps are those requirements deriving from the factors layers as tectonic features, morphological characteristics, geometric attributes of the slope, type of coverage, structures and infrastructures, trajectory of the block and the stop point. The above mentioned steps allow the implementation and calibration of the model for rockfall analysis; in particular, by means back-analysis stage it is possible to determine the restitution and friction coefficients through a comparison of the points where the rock blocks stop in the simulation with the rockfall history stop points. The next step we took is to produce the map of those areas with different degree of risk defined through the density of the trajectories reconstructed through the model. Finally, are presented here two between the cases studied needed to set up the forecasting model for the rockfall trajectories. Catalano R., Valenti V., Albanese C., Accaino F., Sulli A., Tinivella U., Gasparro Morticelli M., Zanolla C., Giustiniani M., 2013 – Sicily fold-thrust belt and slab roll-back: the SI.RI.PRO. seismic crustal transect. Journal of the Geological Society, 170, 451–464

INVENTORY AND CHARACTERIZATION OF SICILIAN BADLANDS

The United Nations Convention to Combat Desertification (UNCCD, 1994) addressed desertification as a global problem defining it as \u201cland degradation in arid, semi-arid, and dry sub-humid areas, resulting from various factors, including climate variations and human activity\u201d. In the Mediterranean areas, this phenomenon results from the interaction of various factors such as climate, lithology, vegetation and land use. The study of the predisposing factors allows the time/space assessment of the phenomenon and a continuous field monitoring allows to quantify the data in terms of vulnerability degree and to develop decision-making tools for integrated land use planning. One of the most fragile ecosystems are the badlands areas in Sicily. Their geological and climatic features (erosive rocks and marginal soils, and highly variable rainfall) and often a negative human impacts (inadequate land use and agricultural practices) led to increasing soil erosion and vegetation degradation, predisposing the terrain to the badlands. Moreover, the slope topography can be considered as a driver factor for the inception and the evolution of the badlands, in particular if we considered the badlands as miniature drainage systems, fully comparable to small river basins. The present work focused on the role of the pre-incision slope topography on the typologies and characteristics of the Sicilian badlands. The badlands areas of the entire Sicily were mapped in order to create an inventory of landforms based on morphological criteria. The digital orthophotos (2007-2008) at a nominal scale of 1:10.000 available in the WebGIS server of the Regione Sicilia and the Google Earth images of the same periods were closely examined. The landforms were digitized as polygons by means of a GIS software and recorded into a geo-database. The channel networks of each badland were traced and their drainage density (D) were calculated. The numbers of furrows directly tributary to the external drainage network were measured by using the index Gully Tributary (GT). This allowed to distinguish two typologies of badlands drainage pattern: dendritic for GT=1 (with only one main furrow) and parallel for GT>1 (with several parallel furrows). For each landform, the pre-erosion topography was reconstructed by filling the incision, using the heights of the watershed divide as point values in a topography interpolation tool in GIS. It represented the slope topography prior to the development of the current drainage network. The pre-incision slope morphometry of each landform was characterized by calculating the Morphometric Slope Index (MSI) considered as general index for slope morphometry. MSI, GT and D were compared via statistics in order to detect the influence of pre-erosion slope morphometry on the typology and the arrangement of the badlands drainage networks

Carta Geomorfologica del bacino idrografico del Rio Spinasanta e note illustrative(Sicilia centro-settentrionale).

Geomorphological map of the Rio Spinasanta river basin and illustrative notes (Central-northern Sicily). The present paper aims to illustrate the geomorphological map of the Rio Spinasanta river basin, in which landforms recognizable on the area are mapped and distinguished according to the responsible geomorphological process. The Rio Spianasanta river is a tributary of the head sector of the Imera Settentrionale river and is contiguous to the regional water divide that separate the northward and southward flowing Sicilian rivers; the geomorphological map has been produced using as support a topographic map on scale 1:10,000. The geomorphological map has been carried out by means of different methodologies, namely geological and geomorphological field surveys, analysis of aerial photos and orthophotos.Moreover, the geomorphological characterization of the area has been supported by the study of the pluviometric conditions and by the analysis of the landforms’ spatial distribution; the latter, which has been carried out using a GIS software, allowed to evaluate the density of landforms on the classes of the lithology parameter and on the classes of slope angle and aspect. The GIS analysis showed that the combinations of the selected parameters control the intensity of the processes and the spatial distribution of the shaped landforms; this fact led to different landscapes recognizable in the studied area. The landforms mapped in the Rio Spinasanta river basin have been distinguished according to the modeling processes in: a) landforms shaped by water erosion processes; b) landforms produced by gravitational processes

Francesco Remotti, 2013, Fare umanità: I drammi dell’antropopoiesi, Bari, Laterza, pp. 235

Book review of Francesco Remotti, 2013, Fare umanità: I drammi dell’antropopoiesi, Bari, Laterza, pp. 235.Recensione di Francesco Remotti, 2013, Fare umanità: I drammi dell’antropopoiesi, Bari, Laterza, pp. 235

Malta and Sicily Joined by Geoheritage Enhancement and Geotourism within the Framework of Land Management and Development

Malta and Sicily, which lie at the centre of the Mediterranean Sea, share a long history and have unique geological and geomorphological features which make them attractive destinations for geotourism. In the framework of an international research project, a study for the identification, selection and assessment of the rich geological heritage of Malta and Sicily was carried out, aiming to create a geosite network between these islands. Based on the experience and outputs achieved in previous investigations on geoheritage assessment carried out in various morpho-climatic contexts, an integrated methodology was applied for the selection, numerical assessment and ranking of geosites. The selection phase was based on three main criteria-scientific, additional and use values-and led to the establishment of a list of 42 geosites (20 in Malta and 22 in Sicily). Besides being spectacular and attractive for tourists, these sites represent the main geomorphological contexts and the various stages of regional morphogenesis of the study areas. The sites selected were assessed quantitatively and ranked according to management and tourism criteria. The results provide both the necessary basic knowledge for joint conservation actions and policies in Malta and Sicily and the elements for creating a link between Malta and Sicily through geoheritage appraisal and tourism development

Rockfall hazard assessment of the Monte Gallo Oriented Nature Reserve area (Southern Italy)

The Monte Gallo area is a carbonate relief that develops a significant nature reserve and highly attracts tourism to the urbanized area of the City of Palermo (Southern Italy). The slopes are affected by several rockfall events, which have also caused death, injuries, material damage, and a strong social and economic impact. Here, a detailed geological and geotechnical study to assess the rockfall hazard relating to two sectors of the mount has been carried out. The hazard assessment at the slope scale was performed based on geological, geomorphological, geomechanical, and seismic analysis. Using both analytical and empirical methods and by means of different software, the reconstruction of the propagation areas for the eastern sector of the Mount was possible. Results were used to better understand the overall structure, characterize the rockfall source areas' kinematics, and recognize the basic failure mechanisms. The obtained runout areas were compared with each other and with those of previous studies conducted in a neighboring area, as well as with the corresponding hazard area maps of the official cartography, which is being updated. It is expected to be supplemented with maps derived from empirical models

Geomorphology of the urban area of Palermo (Italy)

The results of a geomorphological study carried out in the urban area of Palermo are summarized in a thematic map. Field survey, analysis of aerial photographs and topographic maps, consultation of historical documents and maps, stratigraphic and topographic reconstruction from numerous wells and subsoil data, and bibliographic search were performed, in order to display the geomorphological changes produced by man over time in a densely populated area and to define the Anthropocene of the study area. Palermo town rises along large marine terrace surfaces cut by small river valleys and bordered by wide degraded and abandoned coastal cliffs. Over the last 2700 years, this area was affected by remarkable man-made changes to topographic surface and underground, exposing large areas of the city to hydraulic, sinkhole, and landslide risks, and increasing the levels of seismic susceptibility. In light of these results, the produced map is useful for urban planning studies

Combining multi-typologies landslide susceptibility maps: a case study for the Visso area (central Italy)

The research proposes a simple but geomorphologically adequate method to produce a combined landslide susceptibility map. In fact, in a logic of real use, offering type-specific landslide susceptibility maps to land use planners and administration could be not a successful solution. On the other hand, the simple grouping of more types of landslides could be misleading for model calibration considering that the relationships between slope failures and geo-environmental predictors should be conveyed by the abundance of each type of landslide resulting not specific and diagnostic for each typology. In this test, after having produced independent models for flow, slide and complex landslide by exploiting MARS (Multivariate Adaptive Regression Splines) and a set of type-specific geo-environmental variables, a combined landslide susceptibility map was obtained by combining the scores of the three source maps. The combined map was finally validated with a new unknown archive, showing very good performances

Analysis of the Rockfall Phenomena Contributing to the Evolution of a Pocket Beach Area Using Traditional and Remotely Acquired Data (Lo Zingaro Nature Reserve, Southern Italy)

The coastal domain of central western Sicily is characterized by the presence of rocky coasts, which mainly consist of pocket beaches situated between bedrock headlands that constitute ecological niches of great touristic and economic value. In this peculiar morphodynamic system, the sedimentary contributions are mainly derived from the rockfall that affects the back of nearby cliffs or the sediment supply of small streams that flow into it. In this study, we investigated the geomorphological processes and related landforms that contribute to the evolution of a pocket beach area located in a coastal sector of NW Sicily Island. The cliffs in this are affected by several rockfalls, and deposits from these rockfalls also add to the rate of sedimentary contribution. The analysis was conducted through the application of traditional approaches and contemporary methods that have previously been used to forecast the collection of input data in the field, often under difficult conditions due to the accessibility of the sites, and which have been supported by UAV surveys. Through the analysis of the digital models of terrain and orthophotos, geometrical and multitemporal analyses of landforms were carried out. A dedicated software was utilized for the detection of rockfall runout zones and block trajectories and for defining the automatic extraction of rock mass discontinuities. The data were compared with those derived from traditional geomechanical surveys. The availability of the existing and acquired remote sensing data proved essential for this study for both defining the reference geological model and for performing the site-specific analysis of rockfall

Rockfall hazards of Mount Pellegrino area (Sicily, Southern Italy)

A map derived by rockfall analysis at Mount Pellegrino is presented herein. The study area is affected by several phenomena of rockfall which caused numerous damage and a strong social and economic impact. Official reports and maps that give a general assessment of rockfall hazard are available in this respect, however, it would be advisable to provide a more specific cartographic support useful for land management and planning. The drafting of new maps showing the rockfall runout areas is an additional tool that may be used in conjunction with the existing maps as a means of risk mitigation and reduction. On the basis of geological, geomorphological, and geomechanical analysis and exploiting the information relating to a landslides inventory obtained by using both analytical and empirical methods, two different rockfall propagation areas were reconstructed. The final thematic map permit to appreciate the differences and similarities between the obtained runout areas