United States

In highly urbanized contexts for millennia, the presence of underground artificial cavities represents one of the most important opportunity for the investigation of geological subsoil. Thanks to urban geology, it is in fact possible to combine the intrinsic geological aspects and characteristics of a city’s underground with the man-made changes of the original natural landscape. This paper focuses on the investigation of a crucial key point for the geological and geomorphological arrangement of the Perugia’s hill, the capital city of the Umbria region (central Italy). The study case is the area close to the Etruscan Well (third century B.C.), one of the most relevant archeo-geosite in the downtown of the city. Through a multidisciplinary approach moving from a geological and geomorphological data to historical-archaeological ones (Melelli &amp; Rosati, 2019) with information of the hydraulic works of Perugia (Bergamini, 1991), it has been possible to rebuild the architecture of the anthropic cavities and to establish the possible connection with this ancient hydraulic works, in relation to the geological and geomorphological structure of the area. In addition, non-invasive geomatics investigations such as terrestrial laser scanner (TLS) and ground penetrating radar (GPR) have been used. The GPR survey, successful already use in historical urban areas (Ercoli et al., 2016), was planned on the data formerly obtained by the georeferenced TLS survey. The result is a three-dimension visualization of the Etruscan Well and the surrounding area, enriched by the numerous subsoil profile collected. The elaboration of these profiles and their subsequent study have allowed to expand the knowledge on an area as old as it is still unknown: focused on the interpretation of the anomalies found in the subsoil, revealed other artefacts around the Well, such as buried tunnels or possible fragments of ancient roads (Melelli et al., 2021).

SGI 2021

The key role of anthropic underground cavities in the urban geology: the Etruscan Well in Perugia’s upper town (Umbria, central Italy)

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L'Istituto Nazionale di Oceanografia e Geofisica Sperimentale - OGS e il Dipartimento di Matematica e Geoscienze dell'Università di Trieste sono orgogliosi di ospitare il 90° Congresso della Società Geologica Italiana a Trieste dal 14 al 16 settembre 2021. La modalità del congresso è interamente online.

Con il motto "Geologia senza frontiere" questo evento mira a promuovere le Scienze della Terra come disciplina scientifica proiettata nel futuro, oltre i confini geografici, politici e disciplinari, per comprendere meglio l'interno del Pianeta Terra e la struttura del sottosuolo, difendere la società da pericolosi eventi geologici, comprendere meglio la variabilità climatica, pianificare l'utilizzo delle georisorse in modo etico e nel rispetto dell'ambiente.


**Please note, times listed in the SCHEDULE tab (calendar icon) reflect YOUR LOCAL TIME ZONE. The main timezone for this conference will be Central European Summer Time.**

The National Institute of Oceanography and Experimental Geophysics - OGS and the Department of Mathematics and Geosciences of the University of Trieste are proud to host the 90th Congress of the Italian Geological Society in Trieste on 14-16 September 2021.  The Congress will be held entirely online.

With the motto "Geology Without Borders" this event aims to promote Earth Sciences as a scientific discipline projected into the future, beyond geographical, political and disciplinary boundaries, to better understand the interior of Planet Earth and the structure of the subsurface, defend society from dangerous geological events, better understand climatic variability, plan the use of geo-resources in an ethical way and respecting the environment.


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Earth Sciences should be understood not only as necessary for a better understanding of the interior of the planet Earth, but also as a defense of society from dangerous geological events, for the understanding of climatic variations, for the planning and use of georesources in a ethical and respecting and protecting the environment.

In highly urbanized contexts for millennia, the presence of underground artificial cavities represents one of the most important opportunity for the investigation of geological subsoil. Thanks to urban geology, it is in fact possible to combine the intrinsic geological aspects and characteristics of a city’s underground with the man-made changes of the original natural landscape. This paper focuses on the investigation of a crucial key point for the geological and geomorphological arrangement of the Perugia’s hill, the capital city of the Umbria region (central Italy). The study case is the area close to the Etruscan Well (third century B.C.), one of the most relevant archeo-geosite in the downtown of the city. Through a multidisciplinary approach moving from a geological and geomorphological data to historical-archaeological ones (Melelli & Rosati, 2019) with information of the hydraulic works of Perugia (Bergamini, 1991), it has been possible to rebuild the architecture of the anthropic cavities and to establish the possible connection with this ancient hydraulic works, in relation to the geological and geomorphological structure of the area. In addition, non-invasive geomatics investigations such as terrestrial laser scanner (TLS) and ground penetrating radar (GPR) have been used. The GPR survey, successful already use in historical urban areas (Ercoli et al., 2016), was planned on the data formerly obtained by the georeferenced TLS survey. The result is a three-dimension visualization of the Etruscan Well and the surrounding area, enriched by the numerous subsoil profile collected. The elaboration of these profiles and their subsequent study have allowed to expand the knowledge on an area as old as it is still unknown: focused on the interpretation of the anomalies found in the subsoil, revealed other artefacts around the Well, such as buried tunnels or possible fragments of ancient roads (Melelli et al., 2021).

technical paper

Noctis Labyrinthus (NL) is located in the western part of the large extensional province of Valles Mariners and close to the vast volcanic plateau of Tharsis Montes. Within this area, linear pit-chains commonly occur in close vicinity to faults, inside the graben, and mainly connected to swarms of small cracks, generating a complex pattern of interconnected faults and a widespread grid of scalloped pit-chains. Such a striking spatial correlation between faults and pit-chains makes this area a location of interest to study the possible mechanisms of formation and evolution of these features. Previous work interpreted NL as a karst landscape with associated caves and water-related processes (Baioni et al.,2017; Weitz et al., 2016; Jackson et al.,2011; Thollot et al.,2010; Grindrod et Balme.,2010; Bérezi., 2008; Murchie et al.,2007; Johnston et al.,2006; Bibring et al.,2006; Boston.,2004;), a network of lava tubes (leone, 2014) or the result of volcano-tectonic activity (Mège et al, 2003, Schultz, 1998). In this work, we used the orthoimages H3210_0000 and H3221_0000 acquired by the High-Resolution Stereo Camera (HRSC) onboard Mars Express, bearing a resolution of 12.5 m/pixel, and for the surface topography, we utilized an individual Digital Elevation Model (DEM) from Mars Orbiter Laser Altimeter (MOLA) onboard Mars Global Surveyor, with a resolution of ~460 m/pixel. We have mapped all apparent faults and grabens within the selected area (N=3781). Each fault was traced by a single polyline or by a group of polylines when segmented, and we distinguished their size by assigning different colors, while the pit-chains were delimited by a polygon shapefile we performed a detailed analysis of the faults patterns and geometries over different lengths with the aim to provide a comprehensive model for the formation of the complex structural features in Noctis Labyrinthus. According to the occurrence of faults and pit-chains, a clear subdivision can be distinguished between the northern and the southern sectors of the studied area; The northern sector of Noctis Labyrinthus basically consists of smooth terrains, lacking troughs and pit-chains, while in the southern sector, pit-chains are well developed and mostly parallel to the ENE-WSW fault system. The azimuth distribution of fault populations shows two main trends in the rose diagrams: ENE-WSW and NS. The NS faults systems are apparently cross-cut by the ENE-WSW faults system, which seems to occur before pit chains formation. We infer a development of two fault systems potentially produced in response of bidirectional or radial extension, where distinct faults develop perpendicular to each extensional direction. The extension is driven by invariant regional stress field, in pure shear, where faults grow at different scales (Schultz et al., 2000; Turabi and Berg., 2011). We propose that a Synchronous or 2-Phase bidirectional regional extension can be the prime processes behind the formation of the rift systems in NL and the generation of T, L, and X-Shaped intersections between faults (Collanega et al., 2020). The presence of pit chains remains difficult to explain within this setting: the interaction with magmatic activity from the large nearby Syria Planum magmatic complex might have played a role in shaping these structures. In this scenario, dikes intruded below the graben floors might have exploited the local extensional setting creating dilatant conditions in correspondence of major structures. A subsequent pressure drop in the plumbing system might have led to a surface collapse forming the large pit chains. In conclusion, we hypothesize that the complex graben and pit chains system of NL is the combined result of the activity of a bidirectional extension likely in conjunction with the activity of a magmatic plumbing system.

A Volcano-tectonic activity: possible scenario beyond the formation of the rift systems in Noctis Labyrinthus (Mars)

The spectral characterization of planetary surfaces and other solar system objects allows us to obtain geochemical information useful for geological mapping and for understanding the evolutionary history of planets and other celestial objects. Furthermore, identifying planetary surfaces geochemical properties, allow us to characterize volcanic features in order to investigate new volcanic mechanism anomalous on planet Earth, but common in other places. The goal of this work is to geochemically characterize planetary surfaces, through the investigation of their mid-infrared range spectra. We propose a spectral characterization of geological properties by means of comparison between planetary surfaces emissivity spectra, measured by probes, and analog rock samples emissivity spectra, measured in laboratory, obtained from natural melting samples. Principal component analysis, clustering and categorization machine learning algorithms and statistical methodology are utilized to spectral comparison as well as spectral data analysis. These techniques allow us to analyse a large amount of data. We have analysed about 1000 emissivity spectra of a Martian basaltic lava flow located at west of Arsia Mons (3° S, 221,8° E, IAU 2000), at the T=273-300K; about 500 emissivity spectra of Nili Patera, a Martian caldera situated to Syrtis Major Planum (9° N, 67° E IAU 2000), at T=273-300K; both groups measured by Thermal Emission Spectrometer (TES) onboard NASA’s Mars Global Surveyor. Regarding our sample spectra, we have analysed 11 emissivity spectra of samples synthesized at the UNIPG laboratory, measured in reflectance and emissivity at the temperatures of 450, 600, 750 and 900K; other 80 emissivity spectra of rock samples from dataset of the Arizona State University were also analysed. On Mars, magmatic differentiation is present, as occurred in Nili Patera caldera, where THEMIS multispectral images show an evident spectral contrast due to magmatic differentiation. The same contrast is identifiable in our TES spectral analysis. The preliminary results show similar trend for chemical component that we have been analysed. Once chemical and spectral features of our samples will be better characterized, we will be able to define quantitative geochemical constraints in order to make geological maps based on mid-infrared measures.

Comparison of emissivity spectra from Mars surface and laboratory rock samples: preliminary results

The dark terrain of Ganymede is the oldest geologic unit of the satellite, subsequently crosscut by the youngest light terrain. It shows morphotectonic structures called furrows, which are radial or circumferential troughs bounded by high albedo rims and a lower albedo floor. It is assumed that furrows represent a multi-ring basin formed by an ancient impact crater (McKinnon & Melosh, 1980; Prockter et al., 2000). In fact, Galileo Regio’s furrows show a concentric pattern centered at around 20° S 180° W, which is the assumed location of the crater (Prockter et al., 2002; Hirata et al., 2020). Most of them have been preserved in their pristine form, while some have acted as zones of weakness and have been re-used by later tectonic deformation. These zones are likely considered as precursors of grooved terrain formation. In this contribution, we present the structural mapping at the regional scale of the furrows in Galileo Regio, and we identify their hierarchy and tectonic setting originated by strike-slip and shortening. Riedel shear, synthetic and antithetic structures, and conjugate fractures have been identified. Hence, the performed mapping allows to infer the tectonic setting of the furrows and their associated structures, and in turn the (paleo)stress field that affected the area. Galileo Regio has been deformed by the same regional kinematics consistent with the right-lateral transpression that has affected Uruk Sulcus (Rossi et al., 2018). We infer a ≈ NE-SW trending maximum horizontal stress responsible for a shortening associated with strike-slip in the area extending from 180°-120° W to 0°-60° N. This work confirms the key role that transpression has played in the leading hemisphere of Ganymede and further statistical analysis will be performed to support this reconstruction. The produced tectonic model will be used for the scientific preparation of future high-resolution observation that will be performed by the JANUS instrument onboard JUICE mission (Palumbo et al., 2014).

Strike-slip and shortening in the dark terrain of Ganymede

The surface of Ganymede appears as a deeply tectonized environment mainly composed of a brittle icy crust overlying a subsurface global liquid ocean, whose depth was constrained to be between 100 and 150 km (Lucchetti et al., 2020 and references therein). The surface of Ganymede can be subdivided into dark and bright terrains depending on their crater density, differences in albedo and surface morphology. Indeed, the majority of the terrains can be subdivided according to the presence of furrows and grooves features. These structures represent the brittle deformation of the satellite’s icy shell. The study location is between 150W -180W and 30N-10 S in the region of Uruk Sulcus, a NW-SE terrain ~400 km wide and ~2500 km long strongly deformed by grooves. Several hypotheses account for the presence of such structures, namely tilt-block normal faulting (Pappalardo et al., 1998), crustal necking similar to rifting stage in mid ocean ridges (Pizzi et al., 2017 and references therein) or - in the case of Uruk Sulcus - the effect of a major dextral transpression  (Rossi et al., 2020). Also, it has been demonstrated that the spatial distribution of such structures shows a fractal spatial clustering, that implies that the fracture network below the surface can be interconnected and percolating, reaching up to the ~100-150 km-deep ocean (Lucchetti et al., 2020). To better constrain the transpression hypothesis in Uruk Sulcus, we are testing different 3D geomodelling approaches hence deriving more information on both the volume of the fractured brittle ice crust and the most favored location of actual percolation. At present day, 3D geolocial modelling is approaching the planetary geology, as also testified by the outcomes of the PLANMAP Horizon 2020 project (Massironi et al., 2018, 2021; Pozzobon et al., 2020; Penasa et al., 2020; Pozzobon et a., 2021). With the information either derived from direct surface observations and measurements and/or also constrained by geologic interpretation, it is possible to derive a 3D geomodel of the subsurface that represents specific geologic properties or geometries. Such approach allows to refine or confirm the geologic interpretations or provide new useful qualitative and quantitative insights. A preliminar model of Uruk sulcus was built using the global DEM by Zubarev et al., (2017)  as an initial, low-resolution surface. This served as an upper surface boundary to project the structural mapping from Rossi et al., (2020) and also as an anchor point to reconstruct the major Uruk sulcus structures. It was then textured it with the controlled global mosaic from DLR of Voyager 1, 2 and Galileo images at an average resolution of 359 m/pixel. As a lower model boundary, the icy crust is constrained at depth by the ocean-ice interface. In particular we used the depth value calculated using the fractal clustering analysis in Lucchetti et al., (2020) related specifically to Uruk sulcus. We were able to reconstruct a preliminary qualitative model of the fault geometries for GUS1 (Grooves of Uruk Sulcus 1) system deformation (Rossi et al., 2020) as a large-scale structural framework. We performed a first test on a smaller region in the sigmoidal area named S2 and containing the GUS3 (also in Rossi et al., 2020). We extracted a voxel-based volume of icy crust comprised between the surface, the lower ocean-ice interface bounded by the major fault lines delimiting GUS3. At this location a major set of NE-SW high-angle extensional structures arranged in a right-stepping en-echelon geometry are present together with other two grooves families with NW-SE and NS orientations, although lower in number. By exploiting the voxel-based volume and knowing the scaling laws that rule of the size distributions of the grooves and their azimuths, it is possible to  simulate a DFN (Digital Fracture Network) for each of the fractures’ families and to predict possible high-connectivity locations in the fractured ice volumes and their location at the surface. Further analyses will attempt to simulate the movement along the major structures of Uruk backwards and forward in time, in order and to capture the strain in the ice volume and also test the transpression vs necking approach. The 3D geomodelling approach proves to be a promising tool not only for scientific analysis but also to identify interesting target of future JUICE mission (Grasset et al., 2013) observation through the JANUS instrument (Palumbo et al, 2014), where resurfacing or deep fluid expulsions could be more favored.

3D geo-model of Uruk Sulcus structures (Ganymede): insights and implications

Research in urban geomorphology is a relatively recent topic and its theory and practice require continuous updates. Few studies have focussed on issues specifically connected with the cartographic representation of geomorphological processes and landforms in urban environments, with the aim of tentatively reconstruct and clarify the original physical landscape. Among these, recent urban geomorphological surveys conducted in Italian cities proposed new strategies for detecting and mapping human induced modifications to the topography, and anthropogenic landform classification has been recently deepened in the revised Italian national guidelines for geomorphological mapping (Campobasso et al., 2018), proposed by the Working Groups of the Italian Association of Physical Geography and Geomorphology (AIGeo) and the Italian Institute for the Environmental Protection and Research (ISPRA). In this work, natural landforms modified by man and artificial landforms are explored and compared in three Italian cities: Rome, Genoa and Perugia. The comparison is interesting because of the different morphogenetic environment characterizing the 3 cities and also for the differences in the geomorphological survey and mapping. At the same time, in these urban areas, human activities have similarly remodelled the topographic surface and become the most important modelling agent of relief. Many reliefs have been erased, whereas thick layers of anthropogenic deposits covered most of the natural landforms, with the result, for example, of hiding or greatly modifying the natural valley incisions. Geomorphological studies in urban environments allow the reconstruction of the physical landscape before human modifications and the implementation of innovative methodological tools, and an effective legend to represent the urban landforms and their evolution over time.

Geomorphological classification of the landscape in urban areas: anthropogenic landforms in Genoa, Rome and Perugia

Since early 1990s, the advent of satellite-based techniques, such as the Differential Interferometry Synthetic Aperture (DInSAR) (e.g. Curlander & McDonough, 1991) and Global Navigation Satellite System (GNSS), has revolutionized the monitoring of ground level displacements thanks to satellite-based techniques. These observation systems enabled us to control with unprecedented accuracy and resolution deformation phenomena caused by transient events, such as earthquakes, volcanic eruptions and sinkholes, or long-term processes, like subsidence and landslides, thus revealing useful applications in the geological, geotechnical and structural analysis fields (e.g. Lanari et al., 1998; Herrera et al., 2009). Today, the Advanced DInSAR (A-DInSAR) technique is based on high resolution sensors, which monitor the evolution of instability phenomena in any atmospheric and lighting condition, and in both historical centers and archaeological sites. Within this framework, we propose the application of an exhaustive approach for studying both permanent and periodic components of vertical land deformation in the urban area of Naples (southern Italy). Such methodology, successfully applied in the Po Delta area (Vitagliano et al., 2020), is proposed to study the geological risks in urban areas and to evaluate the effects of the anthropic context on the periodic processes related to climate variability. Firstly, a spatial analysis has been carried out to calculate the interferometric velocities of Sentinel-1 and COSMO-SkyMed data in the time intervals January 2016 – December 2019 and March 2017 – December 2020, respectively. The obtained ground displacement and velocity have been used for mapping the stable and unstable urban areas and for evaluating the dependencies between the distribution of the velocity zones and some geological features (e.g. ancient alluvial deposits and paleo-coast lines). Afterwards, a spatial-temporal analysis of continuous GPS data available for a site located in the city center has been performed, which provided a reliable identification of the seasonal trends of the ground displacement. Finally, an automatic cross-correlation procedure developed in Matlab environment was applied to systematically correlate the interferometric trends of each reflection point with the rainfall and sea level oscillations, measured in the same time interval. The correlation process allowed the identification of the most significant dependencies and the triggering mechanisms of the slow soil oscillations, and gave also interesting insights into urban instability processes, such as sinkholes.

Study of periodic dependencies among ground deformation, rainfall and sea level in the city of Naples (Italy)

Landslides represent a serious threat in hilly and mountainous areas of the world. Usually, shallow landslides are triggered by intense or prolonged rainfalls and frequently may evolve into potentially catastrophic flow-like movements. Because of the capacity of these phenomena to travel long distances, buildings and infrastructures located in areas improperly deemed safe can be affected. Landslides can be destructive events when mobilize large volumes of soil and/or rock and undergo long distances. It is impossible to stop such events and the best way to prevent disasters is to reduce or avoid the related risk (Carrara et al., 1999). Landslide risk assessment is a research topic of growing interest across the scientific community. Such interest stems from the awareness of the still dramatic impact of landslides on the socio-economic development of vast areas and the concurrent boosting request for urbanization across landslide-prone areas (Petley, 2012). Risk mitigation measures must necessarily focus on the vulnerability of the exposed elements and, in particular, of buildings potentially impacted by landslides. The destruction of these structures can provoke enormous economic losses and endanger the people inside them. On this basis, a study concerning landslide impacting settlements in the Cuenca area (Ecuador) has been carried out thanks to the availability of two fundamental datasets: landslide inventory map (LIM) and information on building's presence. A LIM represents a fundamental tool to display information on landslides activity and their multi-temporal evolution (Corominas et al., 2014). In most cases, inventories are discontinuous over time and so-called event-based landslide inventories are available, which are landslide inventories based on a singular severe event (rainfall- or earthquake-induced). In this case, LIM was derived from interferometric data and the visual interpretation of aerial photos integrated and validated by field investigation. The surveyed slope failures were classified according to Cruden & Varnes (1996). As concerns buildings information, it was possible to obtain multi-temporal data on the evolution of buildings constructed from 2010 to 2020. From this knowledge, it was possible to note that over time, due to the steady population increase, most of the buildings were built in correspondence of the mountainous areas surrounding the Cuenca center. Thanks to the availability of these data, it can be stated that the buildings, over time, have been built in areas that can potentially be affected by landslides.

Landslides affecting buildings in rapidly growing areas of Cuenca (Ecuador)

Consequences of climate change are often more obvious on global scale, but downsizing at regional scale implies a good knowledge of territory, its intrinsic fragility and the urban characteristics. Underlining and predicting trends of climate variables within regional and especially municipal scales to promote adaptation and mitigation strategies is the purpose of the SECAP (Supporting Energy and Climate Adaption Policies). A practical approach to analysing the impact of climate change aimed at driving specific policies and actions on an urban scale is the SECAP template, the official report of the Covenant of Mayors initiative. Using different methodologies, we have examined various extreme climatic events and climate projections at the regional scale, downscaling to the city of Trieste and other rural areas: the heat waves, the drought, the wildfires, the heavy precipitations, and all the consequences linked, for instance, to the river floods or episodic storm surges combined with the sea level rise. All projections seem to indicate potential significant variations in intensity of extreme events or frequency during the different seasons from a mid-term/long-term timeframe (2050-2100). The intensification of such extreme events amplifies the effects of sea level rise and the temperature increase on the territory, causing important consequences in terms of geological hazard, such as river flood, coastal flood and landslide, especially in a highly urbanized contexts like the city of Trieste. In order to quantify the cause-effect relationships requested by the SECAP template, we propose a methodology based on the intrinsic geological characteristics and vulnerabilities of the territory. In the template, the current hazards are considered in term of probability and impact, whereas for the future hazards the definition of the expected change of intensity and frequency, as well as the timeframes are requested. The quantitative approach permits to scale the qualitative “low, medium, high” attributes, too generic as indicators. For the river flood, the Regional Hydrogeological Planning Plan (PAI) and the risk maps of the Floods Directive have been analysed, parameterizing the hazard in a quali-quantitative way and highlighting the vulnerable areas. For the coastal flood we have superimposed predictive models of inundation of the city to the digital terrain model, quantifying the coastal length involved in the phenomenon. For landslide, we analysed and revised the regional landslides database in terms of the number of landslides compared to the extent of the municipal area and the type of land use. Finally, for each geological hazard, the effects of the foreseen intensification in extreme events were assessed. The analyses obtained show an increasing trend in these geological phenomena, and in general in risk. These considerations form the basis for the drafting of SECAP and local planning.

A quantitative approach for the urban adaptation policy to climate change (SECAP): an application to some geological hazards

The town of Naples is located in the eastern sector of the Campi Flegrei, a volcanic field placed along the Tyrrhenian flank of the southern Apennines. The geological evolution of Naples is strictly related with the volcanic history of the Campi Flegrei (Ascione et al., 2020, and reference therein). The present-day topography results from the interaction between volcanism, bradyseism and sea-level variations and is prone to the development of a dense network of ephemeral rivers, some of which develop along faults and fractures affecting the volcanic units (Ruello, 2008). According to the features of river networks, the town of Naples may be sub-divided in three sectors. To the west of Naples (e.g., near Agnano, Pianura, Soccavo, Fuorigrotta, Bagnoli, Posillipo and Chiaia), river network consists of small, often isolated, valleys (length around 1 km), dissecting both the inner and outer flanks of the Campi Flegrei caldera (whose  slope also exceeds 30°). In the central sector of Naples (e.g., near Vomero, Camaldoli, Capodimonte and the historical centre), river network is more organised, with “small” valleys converging towards “large” valleys. Consequently, large drainage basins may be recognised, which collect water from the hilly areas towards the low topography, very densely urbanised, historical centre. To the east of Naples (e.g., near Poggioreale, Ponticelli, San Giovanni a Teduccio), river network consists of a main trunk, the Sebeto River, flowing in the related alluvial plain. Most of the river network is very hard to be recognised, being overwhelmed by the growth of the town. A typical example is the Sebeto River, which actually flows below ground level and whose mouth has been included in the harbour area. The lack of river valleys is apparently in contrast with the alluvial events that struck Naples since historical times, as testified by alluvial deposits found in the subsurface (Cinque et al., 2011; Romano et al., 2013). Some of these events are pretty “famous”, such as those one that often hit the quarter named Sanità, which are known as the “Lava dei Vergini” due to volcanic clasts transported during the alluvial event. Noteworthy, the memory of “hidden” rivers remains in the name of many streets, as testified by the terms “Cupa”, “Cavone”, “Vallone” and “Arena” that identified sectors of the urban areas developed on river valleys. These features make Naples an interesting study area to analyse the interaction between natural processes and anthropic loading, and to make people aware of landscape dynamics.

The hidden rivers of Naples (southern Italy)

Gubbio (Umbria, central Italy) was built on the slope of Mt. Ingino (908 m asl), on the left bank of Torrente Camignano, where the vast flat area known as the "Gubbio Plain" begins. The debris at the base of the slope of Mt. Ingino is delimited by two alluvial fans, one of the Torrente Camignano at NW (almost flat) and the other of the Fosso Cavarello at SE (more steep). The slope debris shows an evident morphological step (H max. about 20 meters) oriented parallel to the slope itself. This produces a marked discontinuity in the slope profile and affects the whole width of the detrital body. This kind of escarpments is frequent on the slope debris at the base of the mountains of the Gubbio chain. This ridge constitutes the NE flank of an anticline, formed during the Apennine orogeny. It is broken at the core by a normal fault with considerable upthrow (over 1500 meters) and with direction parallel to the axis of the fold itself. These escarpments are likely to be interpreted as the surface morphological expression of recent phases of tectonic activity linked to the Gubbio fault (which, therefore, has to be considered an active and capable fault). A bull of Pope Clement III in 20 October 1188 and a diploma of Emperor Henry VI in 5 June 1191 suggest that when the Eugubini (the people of Gubbio), in the second half of the 12th century, decided to build the new city "on the mountain", they identified how the most suitable place for the fortified urban space, the one upstream of the great escarpment which divided in two parts the slope debris of Mt. Ingino. Later, especially during the 13th century, a consistent urbanization took place in Gubbio. This led to an inevitable expansion downstream of the urban core, which essentially took the shape of the current historic center of the city. On the specific topic of the relationship between the definition and development of the late medieval city of Gubbio and the conformation of the slope debris on which it was built, some preliminary considerations have already been formulated (Sannipoli, 2013). The research in progress is aimed at investigating some specific aspects of this interesting problem of urban geomorphology, both as regards a more precise definition of the geomorphological characteristics of the site, and in relation to the transformations of the first urban core of Gubbio, over the 13th and 14th centuries. Above all, it seems interesting to define what these transformations entailed, as regards the alterations of the geomorphological peculiarities of the site where the city was born and had subsequently developed.

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A Volcano-tectonic activity: possible scenario beyond the formation of the rift systems in Noctis Labyrinthus (Mars)

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Ancient waters in historical city centers: collectors of multidisciplinary knowledge

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