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Palermo is a populous city situated on the northern coast of Sicily, bordered by the Tyrrhenian Sea. This central part of the Mediterranean Sea features dramatic bathymetry, numerous subaqueous landslides and is also the epicentre to many subaqueous earthquakes. As such, the region is an area prone to tsunamis. This investigation uses the Cornell Multi-Grid Coupled Tsunami (COMCOT) tsunami modelling package to simulate five near-field landslides, and five near-field earthquakes regarded as worst-case credible scenarios for Palermo. The seismic simulations produced waves on a very small scale, the largest being c. 5 cm at its maximum height, and none of the earthquake-generated tsunami waves produced any measurable inundation. The landslide simulations produced larger waves ranging from 1.9 to 12 m in maximum height, two of which resulted in inundation in areas surrounding the Port of Palermo. Sensitivity analysis identified that fault width and dislocation as well as landslide-specific gravity did have significant influence over maximum wave height, inundation and maximum run-up wave height. There are methodological issues limiting the extent to which this study forms a comprehensive tsunami hazard assessment of Palermo, such as gaps in bathymetric data, computational restrictions and lack of a probabilistic element. These issues are counteracted by the fact that this study does serve as a robust first step in identifying that landslides in the region may produce larger tsunami waves than earthquakes, and that the directionality of mass movement is critical in landslide-driven tsunami propagation in the southern Tyrrhenian region.

Il Coralligeno di piattaforma è un indicatore ambientale e hotspot di biodiversità nelle zone marine costiere. Poiché esso viene considerato un ecosistema marino vulnerabile, numerose sono le azioni volte alla sua completa caratterizzazione e mappatura. L'obiettivo del lavoro è di confrontare differenti metodologie utilizzate nell’analisi della distribuzione del Coralligeno di piattaforma, applicate al settore offshore della Sicilia nord-occidentale. Il focus del lavoro consiste nell’evidenziare come l’approccio multidisciplinare sia fondamentale nelle fasi di individuazione, caratterizzazione e predizione statistica della distribuzione delle associazioni biocenotiche, al fine di eseguire una mappatura degli habitat costieri. L'area di studio si trova nel tratto di piattaforma continentale antistante i Monti di Palermo e compreso tra Isola delle Femmine e Capo Gallo. Le mappe di distribuzione degli habitat possono essere ottenute attraverso tre approcci metodologici differenti. Il primo proviene dallo studio geologico-geofisico dei fondali, che ha permesso di cartografare le comunità bentoniche sulla base dei caratteri morfo-batimetrici. In questo senso il Coralligeno di piattaforma è stato classificato secondo Ballesteros (2006) e Giaccone (2007), differenziandolo in banchi ed orli e infralitorale e circalitorale, rispettivamente. Il secondo approccio è quello biologico che consiste nel calibrare le facies acustiche ricavate dall’interpretazione dei dati Side Scan Sonar con i dati di campioni di fondo e validati attraverso immagini ROV; in questo modo vengono mappati e descritti i depositi di coralligeno con i relativi parametri quantitativi. Il terzo approccio è quello statistico, basato sul modello di massima entropia (MaxEnt) che permette di ipotizzare la distribuzione della specie sulla base di dati di presenza (presence-only) e di parametri ambientali mappati per l’intera area di indagine (Fig. 1). I parametri considerati sono: batimetria, acclività, esposizione, presenza di fluidi, aree ad erosione, sedimentologia. Oltre alla predizione sulle presenze della specie considerata, l’analisi statistica ha consentito di individuare i fattori che controllano la distribuzione del coralligeno lungo il margine, quali: fondali sabbiosi e, in subordine, sabbioso-limosi e substrato roccioso, inclinazione elevata, assenza di processi erosivi in atto ed emissione di fluidi. L’integrazione di dati provenienti da tre diversi approcci ha reso possibile definire con maggiore dettaglio la distribuzione dei vari generi che costituiscono l’associazione a coralligeno dell’infralitorale (Rhodophyta, Cnidaria e Chlorophyta), che si distribuiscono prevalentemente lungo il limite piattaforma interna-piattaforma esterna (coralligeno di orlo), ad esclusione di alcune associazioni in banchi (probabilmente legati ad emissioni di fluidi. Questo approccio può costituire uno strumento utile nell’individuazione e monitoraggio di aree marine da sottoporre a tutela ambientale.

The Sicily dominates the central Mediterranean Sea. The Northern Sicily Continental Margin (NSCM) is a segment of the Appeninic-Tyrrhenian System whose upbuilding refers to both the postcollisional convergence between Africa and a very complex “European” crust (Bonardi et al., 2001) or AlKaPeKa (sensu Boullin, 1986) and the opening of the Tyrrhenian back-arc basin. Seismostratigraphic and structural analysis of a large number of available (from ViDePi project) and unpublished (from Department of Earth and Marine Science of the University of Palermo) multichannel seismic reflection profiles acquired across the NSCM, allow us to produce an accurate seismotectonic map, in order to obtain a useful tool for the assessment of the seismic hazard of the sea-land region. This first seismotectonic map has been realised from the overlapping of different geological layers that represent the main identified seafloor and sub-seafloor features, such as tectonic elements (normal and revers faults), earthquakes, heat flow, gravimetric (Bouguer) and magnetometric anomalies, Moho depth, masswasting, fluid escape structures (e.g. pockmarks, mounds, gas flares, and gas chimneys), sedimentary successions, and lateral and vertical motions. The NSCM is suitable to test this approach because it is located in a transitional area between the Sicilian-Maghrebian chain to the south and the Tyrrhenian back-arc basin to the north. Along this transect the Moho depth ranges from about 10 km, in the Marsili bathyal plain, to about 40 km, towards the northern Sicily coast. The Bouguer anomalies change from 180 mGal in the Tyrrhenian region to negative anomalies in central Sicily (-100 mGal), while positive magnetic anomalies characterize the volcanic edifices, both submerged and buried. While, the heat flow shows very high values across the southern Tyrrhenian Sea (200 mW/m-2) that decrease (30- 40 mW/m-2) towards the stable sector of the foreland area (Iblean plateau in SE Sicily). Along the NSCM, we distinguished, at a regional scale, different shallow and deep seismogenetic volumes. The eastern part of the Sicilian continental margin is characterised by a deeper seismicity related to the Ionian subduction, which is prevailingly linked both to extensional fault systems (Pollina, Messina strait) and to rightlateral NW-SE transcurrent systems (Vulcano- Lipari and Tindari-Giardini). While the western region shows shallow earthquakes (up to 25 km) of low to moderate magnitude (max Mw 5.9 on September 2002) occurring along an E-W trending belt and resulting from the brittle deformation of the Maghrebian chain. The focal mechanisms related to the main seismic shocks are in agreement with a dominant NW-SE compressive offset direction, with a right strike-slip component, and an antithetic NE-SW fault trend. Evidences of mass-wasting processes have been identified across the continental shelf and the continental slope and their spatial distribution, geometry, and seismic character suggest that the fluid seepage, oceanographic processes and the slope oversteepening could be important preconditioning factors, while the tectonic activity showing fault displacements during earthquakes is the main trigger. During the last 125 ky tectonic activity is evidenced by an uplift/subsidence patterns, decreasing from E to W. The continental regions are raised while offshore areas are subsiding, suggesting the occurrence of vertical differential movements. The GPS measurements document the active deformation with differential movements of individual blocks northwarddirected, in agreement with the shallow seismicity, as well as with the convergence between Sicily and Sardinia, with values of about 2-6 mm/y. The first step of this work produced the detailed seismotectonic map between the Castellammare and Palermo gulfs, including both the terrestrial and marine areas. Across the NSCM, we defined two main seismogenetic volumes that are produced by a NW-SE oriented compressional stress field defining an intraplate shallow seismogenetic zone. Though these results are only preliminary, we are developing a scientific product that can provide useful information in terms of seismic hazard in a complex region that includes both continental and marine sectors. Therefore, the identified geological features may be potentially geohazard elements for the neighbouring population and for the near goods, as well as submarine infrastructures (i.e. cables) and our seismotectonic map represent an important tool for monitoring the potentially seismogenic structures and assessing geohazards in marine and coastal environments.

Il margine continentale della Sicilia settentrionale è caratterizzato dalla presenza di pericolosità geologiche (sismicità, vulcanismo, risalita di fluidi e movimenti di massa) che espongono questa regione a rischi geologici marini, con potenziale di generazione di tsunami. Gli tsunami sono onde anomale solitarie legate a movimenti verticali improvvisi dei fondali. Le caratteristiche principali di un’onda anomala sono rappresentate dall’elevata lunghezza d'onda e da un’altezza che varia notevolmente durante la propagazione. L'obiettivo di questo lavoro è quello di calcolare il run-up associato a tsunami generati da frane. Nel nostro caso sono stati presi in esame due settori della costa settentrionale siciliana, Golfo di Palermo e Golfo di Patti, dove l’analisi di dati geofisici ad alta risoluzione (morfobatimetrici e sismici) mette in evidenza tra gli elementi morfologici numerose frane sottomarine. In letteratura per calcolare il valore di run-up si usano diversi algoritmi che generalmente hanno come incognita l’ampiezza dell’onda in corrispondenza del punto sorgente. Partendo dalle caratteristiche morfometriche della frana, l’ampiezza viene calcolata attraverso la formula proposta da McAdoo (2004). In questo lavoro, sono state parametrizzate tutte le frane riconosciute nell’area e di esse sono stati calcolati i valori di run-up di eventuali onde anomale attraverso vari algoritmi (Gedik et al., 2005; Federici et al., 2006; Xi Zhao et al., 2010; Bryant 2008). Queste formule impongono alcune condizioni, che risultano essere “cautelative” sotto il profilo della pericolosità: 1. l’altezza d’onda non subisce variazioni legate alla morfologia della costa; 2. l’energia persa durante la propagazione è zero; 3. l'energia si trasforma istantaneamente da cinetica a potenziale durante la propagazione. Successivamente è stato calcolato il run-up di frane storiche che hanno effettivamente generato uno tsunami, ed i risultati ottenuti attraverso l’applicazione di queste formule sono stati confrontati con i valori reali. Ciò ha consentito di evidenziare gli algoritmi che descrivono al meglio i fenomeni storici, fornendo uno strumento per orientare la scelta della formula più idonea. Infine, dall’analisi grafica della relazione tra valori di run-up ed ampiezza d’onda in prossimità del punto sorgente è stata estrapolata una funzione utile per calcolare il run-up in maniera speditiva.

Active processes in the Northern Sicily Continental Margin (NSCM) have been analysed to produce a seismotectonic map, in order to obtain a useful tool for the assessment of the seismic hazard of the sea-land region. The seismotectonic map is composed of overlapping layers that represent the distribution of different features, such as lithostratigraphy, tectonic elements, seismicity, heat flow, gravimetry, magnetometry, Moho depth, horizontal and vertical movements, submarine landslides, fluid emissions, outlining the mutual relationship and the active structures. The NSCM is suitable to test this approach because it’s located in a transitional area between the Sicilian-Maghrebian chain to the south and the Tyrrhenian back-arc basin to the north. Along this transect the Moho depth ranges from about 10 km, in the Marsili bathyal plain, to about 40 km, towards the northern Sicily coast. The Bouguer anomalies change from 180 mGal in the Tyrrhenian region to negative anomalies in central Sicily (-100 mGal), while positive magnetic anomalies characterize the volcanic edifices, both submerged and buried. The heat flow values are high in the Tyrrhenian Sea (200 mW/m-2), decreasing (30-40 mW/m-2) towards the stable sector of the foreland area (Iblean plateau in SE Sicily). At a regional scale, in the NSCM we distinguished different seismogenetic volumes, both shallow and deep. The deep seismicity, relative to the Ionian subduction, is prevailing in the eastern margin, but the shallow events are the result of the brittle deformation of the Maghrebian chain. In the western sector, shallow hypocentres occur along an E-W belt, with focal mechanisms coherent with a NW-SE compression. To the East seismicity is linked to NW-SE trending extensional to right-lateral transcurrent fault systems. During the last 125 ky tectonic activity is evidenced by vertical movements, decreasing from E to W; moreover, while the continental sectors are raised, offshore areas are subsiding, suggesting the occurrence of vertical differential movements. The GPS values document the active deformation with differential movements of individual blocks northward-directed, in agreement with the shallow seismicity, as well as the convergence between Sicily and Sardinia, with values of about 2-6 mm/y. The first step of this research produced the detailed seismotectonic map between the Castellammare and Palermo gulfs, including both the emerged and marine areas. In this sector we defined two seismogenetic volumes, produced by a NW-SE oriented compressional stress field, and defining an intraplate shallow seismogenetic zone. Though these results are only preliminary, we are developing a scientific product that can provide useful information in terms of seismic hazard in a complex region that includes both continental and marine sectors. Therefore, it could represent an important tool for monitoring the potentially seismogenic structures and assessing geohazards in marine and coastal environments

During the Messinian salinity crisis (MSC) (from 5.97 to 5.33 Ma), the Mediterranean Sea became disconnected from the world's oceans and a fast and continuous evaporation resulted in its partial desiccation. One of the theories for the end of the MSC postulates that a large volume of Atlantic waters entered the Mediterranean Sea through the Gibraltar Strait and rapidly refilled the Mediterranean basin in an event welldocumented known as the Zanclean Flood. The pathway of the Zanclean flood during its passage from the western to the eastern Mediterranean Sea is unclear. The aim of this study is to understand the effects of the Messinian palaeotopography of the southern Tyrrhenian Sea on the dynamics of the Zanclean flood. We analysed a large number of multichannel seismic reflection profiles acquired in the Northern Sicily Continental Margin (NSCM), calibrated with stratigraphic log from the Agip/ENI wells, and high-resolution multibeam data showing the present-day morphology., peer-reviewed

The main aim of this work is to statistically predict the distribution of Vulnerable Marine Ecosystems (VMEs) along the continental shelf regions of the northern Sicilian margin (southern Mediterranean). The considered habitats, already mapped in the area on a qualitative base, are the Posidonia oceanica and Cymodocea nodosa seagrasses and the Coralligenous biocenosis. Posidonia oceanica and Coralligenous are considered as VMEs owing to their value as environmental indicators and biodiversity hotspots in coastal marine areas. For this reason, several actions were aimed in recent years to their complete characterization and mapping. The study area is located in the continental shelf of the northern Sicily margin, between the Cape San Vito (Gulf of Castellammare) and Cape Zafferano (Gulf of Palermo). Different physical characteristics of the seafloor were extracted from a database acquired in recent years in the frame of official national cartography (CARG) and hazard assessment (MAGIC) Italian Projects, including geological and geophysical data (seabed sampling, ROV footage, multibeam bathymetry, backscatter maps, high resolution seismic reflection records) The ultimate goal is to apply a statistical methodology allowing to predict the distribution of marine habitats from a “presence only” sampling dataset. This target was pursued by using a multidisciplinary approach, including abiotic (i.e. depth, morphological and hydrodynamic features, type of seabed) and biotic components (benthic communities) that define and characterize the mapped habitats. Predictive maps are based on the Maximum Entropy model (MaxEnt), a statistical method based on punctual occurrence of specimen (presence-only). The punctual occurrence of the three habitats was already known, whilst we considered the bathymetry, seabed steepness, aspect, fluid escape, erosional areas and sediment type as physical features for the model. The analysis was also aimed to test the performance of models obtained by choosing the training samples with different criteria. Therefore, different outputs (42 in total) have been produced by selecting samples on the basis of the area (regional analysis), the type of coasts (morphological) or randomly (random). Moreover, the models were built up both with only training samples either with training and test samples to obtain more constrained distribution patterns. Almost all the created predictive models produced good performances, with statistical parameters (gain, AUC standard deviation) very positive on average. The models derived from the regional analysis resulted to be more performing than the others, with the random-derived being the worst. The response curves pointed out that bathymetry and sediment types are the most important physical features influencing the distribution of the mapped VMEs, whereas aspect and slope are not-independent variables. These outputs also provided important information and constraints on the favorable environmental conditions for the three habitats. Results from this preliminary statistical modeling appears potentially useful in the evaluation of important environmental parameters, allowing to draw the broad distribution of marine habitats in areas where only presence data are available, and can represent a contribution in the design and monitoring of marine protected areas.

The main aim of this work is to statistically predict the distribution of Vulnerable Marine Ecosystems (VMEs) along the continental shelf regions of the northern Sicilian margin (southern Mediterranean). The considered habitats, already mapped in the area on a qualitative base, are the Posidonia oceanica and Cymodocea nodosa seagrasses and the Coralligenous biocenosis. Posidonia oceanica and Coralligenous are considered as VMEs owing to their value as environmental indicators and biodiversity hotspots in coastal marine areas. For this reason, several actions were aimed in recent years to their complete characterization and mapping. The study area is located in the continental shelf of the northern Sicily margin, between the Cape San Vito (Gulf of Castellammare) and Cape Zafferano (Gulf of Palermo). Different physical characteristics of the seafloor were extracted from a database acquired in recent years in the frame of official national cartography (CARG) and hazard assessment (MAGIC) Italian Projects, including geological and geophysical data (seabed sampling, ROV footage, multibeam bathymetry, backscatter maps, high resolution seismic reflection records). The ultimate goal is to apply a statistical methodology allowing to predict the distribution of marine habitats from a “presence only” sampling dataset. This target was pursued by using a multidisciplinary approach, including abiotic (i.e. depth, morphological and hydrodynamic features, type of seabed) and biotic components (benthic communities) that define and characterize the mapped habitats. Predictive maps are based on the Maximum Entropy model (MaxEnt), a statistical method based on punctual occurrence of specimen (presence-only). The punctual occurrence of the three habitats was already known, whilst we considered the bathymetry, seabed steepness, aspect, fluid escape, erosional areas and sediment type as physical features for the model. The analysis was also aimed to test the performance of models obtained by choosing the training samples with different criteria. Therefore, different outputs (42 in total) have been produced by selecting samples on the basis of the area (regional analysis), the type of coasts (morphological) or randomly (random). Moreover, the models were built up both with only training samples either with training and test samples to obtain more constrained distribution patterns. Almost all the created predictive models produced good performances, with statistical parameters (gain, AUC standard deviation) very positive on average. The models derived from the regional analysis resulted to be more performing than the others, with the random-derived being the worst. The response curves pointed out that bathymetry and sediment types are the most important physical features influencing the distribution of the mapped VMEs, whereas aspect and slope are not-independent variables. These outputs also provided important information and constraints on the favorable environmental conditions for the three habitats. Results from this preliminary statistical modeling appears potentially useful in the evaluation of important environmental parameters, allowing to draw the broad distribution of marine habitats in areas where only presence data are available, and can represent a contribution in the design and monitoring of marine protected areas.

The southern Sicily coasts represent an important contribution to Italian tourism and marine geological processes in the Sicily Channel could pose a significant risk to neighbouring populations and goods. In this work, we are presenting the first results of the data collection that allowed us to identify and map several geological elements that can be used to assess submarine geohazards in the Sicily Channel. By using multibeam data and high-resolution seismic reflection profiles acquired during the ACUSCAL 2015 Cruise, we defined the characteristics of the morphostructural highs, and the morphology of slope failures and the stratigraphy of the mass transport deposits (MTD). In particular, we studied in detail the Graham Bank, which is located in a shallow sector of the north-western Sicily Channel at a distance of 45 km from the Sicilian coastline, where seven seamounts (M1-M7) have been identified and studied in detail within a small area, between 10 and 350 m deep. Their morphometric parameters allowed classification to be implemented on a shape basis. The volcanoes are 115-180 m high and 500-1500 m wide. M2 and M3 (3.5 km X 2.8 km) form the Graham Bank. Most of them show strongly inclined flanks with an average slope of 30°. Most of these seamounts are aligned along two trends (NW-SE and N-S), parallel to the main tectonic structures of the Sicily Channel. The identified structures show physical characteristics, which are very similar to several submarine volcanoes described elsewhere on the seafloor, allowing to conclude that they are volcanic seamounts. In this regard, it is important to highlight that the Graham Bank was affected in the last 100 years, by many eruptions (Colantoni et al. 1975). Furthermore, we distinguished slope failures relating to different mechanisms. In the western flanks of the M2 and M3, volcanic activity and concurrent up-slope triggered mass failures. In the eastern flank M2 gravitational collapse of volcanic edifices is mainly linked to neotectonic activity and volcanism. In the central part of the study area, a MTD is linked to neotectonic activity and to the rise up of volcanic rocks. These MTDs were mapped and described as potential tsunamigenic elements and their volumes were estimated. This work allowed us to understand geological features and processes in a tectonic-volcanic environment, which may represent a threat for coastal areas of the southern Sicily.

The North Sicily continental margin is a very active region located in a transitional area between the Sicilian- Maghrebian Chain to the south and the southern Tyrrhenian Sea to the north. Strong seismicity, active tectonics and volcanism, fluid escape, high sediment supply and widespread mass movements exposed this region to marine geohazards, with a potential for tsunami generation (e.g. Messina 1908, Stromboli 2004 events). In recent years, high resolution swath mapping and high resolution to high penetration seismic reflection profiles have been collected during several oceanographic cruises, in the frame of the MaGIC and CARG projects. Morphobatymetric and geoseismic analysis evidenced the main hazard elements and allowed the production of risk maps. Available data revealed that one of the most common mechanisms associated with marine geo-hazards is due to submarine mass failure processes, genetically linked to other processes active in this margin (canyon, gas venting, volcanism, tectonic structures, volcanoes, high sedimentation rate). With the aim to assess the risks linked to landslide-generated anomalous waves we selected two different sectors of the North Sicily continental margin, located in the western (Gulf of Palermo) and eastern (offshore Patti) coasts. These area were selected based on their morphologic, stratigraphic and tectonic setting and for the large amount of morphostructural elements. The working flow developed through different steps as follows: • identification and mapping of the main morphobathymetric elements affecting unstable areas; • characterization and morphometric analysis of landslide scars (ten Brink et al., 2006) selected on the base of their hazard potenzial; • computation of parameters (wavelenght, velocity, amplitude) of landslide-generated anomalous waves (Rahiman and Pettinga, 2006); • modelling tsunami runup expected by the largest failure volume, breaking on the Sicily coastline, based on Green law relations and solution of the Boussinesq equations (Choi et al., 2006). In detail, we obtained values of maximum run-up of 6.6-9.1 m for the Gulf of Palermo and 6.3-13.3 m for the Patti offshore. However the obtained values appear to be overvalued because the model foresees a precautionary scenario. Moreover the next step will be the assessment of inundation, taking into account the morphologic features of the coastal area and the roughness, land-use and urbanization of the affected areas, concerning a wider concept of risk assessment.

Multibeam bathymetric data revealed the occurrence of atrain of bedforms along a gully system in the Gulf of Palermo, Southern Tyrrhenian Sea. The observed gullies, located in the westernmost sector of the Gulf of Palermo, incise the outer shelf at a depth of 120 m and converge at the Zafferano Canyon, connecting to the Palermo Basin at a the depth of 1300 m. Bedforms develop along these gullies and along the thalweg of the canyon, displaying an average wavelength of 200 m, with maximum values of 340 m. Their gully floor location combined with their wave length, upslope asymmetry and crescent shape point to a possible cyclic steporigin of these bedforms. Preliminary numerical modeling suggest that, assuming that these bedforms were formed by cyclic steps in turbidity currents, these flows might have been few meters thick and have had velocities in the range of 0.2-1.5 m/s.

18 pages, 13 figures, 1 table, We present here for the first time a morpho-structural study of the submarine sector of the Ustica volcanic edifice, located in the south-western Tyrrhenian Sea, considered as an inactive volcanic system, middle Pleistocene in age. The main aim of this research study is to unravel the submarine dynamics along the slope sectors of the Ustica volcano, in order to provide new insights on one of the most tectonically active regions of the Central Mediterranean during the Quaternary. We analysed and interpreted an integrated seismo-acoustic data set consisting of multibeam swath-bathymetry, sub bottom profiles, single-channel seismic reflection records, all of them acquired during the last two decades. The seismostratigraphic analysis indicates that the Ustica volcano is composed by a sequence of lava flows and pyroclastic products, whose geometry can be interpreted as the consequence of combined upward growing and northward shifting of the volcanic centers. The mapped geomorphological elements distributed along the submerged slopes were classified based on their specific morphogenetic process. The achieved results reveal that volcanic, tectonic, oceanographic and gravity processes interacted in shaping the complex current physiography of the volcanic edifice, which is characterized by extremely uneven submarine flanks. The northern region is characterized by the widespread occurrence of well-preserved cones, probably linked to the last submarine volcanic activity of the area. Along the eastern sector, elongate gullies and linear furrows locally incise the shelf break and develop downward producing slope failures. Furrows and gullies represent the main conduits for flushing sediments through various types of flows and mass wasting, from the shallow sectors to the bathyal plain. Along the southern and eastern region slope failures processes carve almost totally of the shelf edge and mainly propagate through retrograding collapses. Further on, the southern region is mainly shaped by E-W and N-S trending fault escarpments that may have triggered the largest slope failures of the area. The main results of this study contribute to improve the understanding of the geological processes and geodynamic activity between the Northern Sicily Continental Margin and the Tyrrhenian Basin and represent a baseline for assessing the geo-hazard potential on the Ustica Island, We acknowledge the CARG Project (Geological Maps of Italy) funded by the ISPRA-Italian Geological Survey and the Italian National Research Projects MaGIC (Marine Geological Hazard along the Italian Coast) funded by the Italian Civil Protection Department.-- With the funding support of the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S), of the Spanish Research Agency (AEI)

A three-stage evolution has characterized the Sicilian Fold and Thrust Belt (SFTB) during the last 15 My: two main thin-skinned shortening events involving mainly Meso-Cenozoic carbonate units, followed by thick-skinned thrusting involving Plio-Pleistocene deposits in the frontal area as well as the crystalline basement in the inner and deeper sector of the chain. We investigated the northern Sicily continental margin, by using differently-penetrative seismic reflection data and new field surveys, which revealed, both offshore and onshore, north-vergent compressional structures that affected the tectonic edifice during Quaternary time. These structures, correlated with the kinematic setting pointed out by seismicity and GPS measurements, could disclose an important change in distribution and orientation of deformation in the frame of the Africa-Europe convergence. Our hypothesis is that the most recent tectonic processes in the northern Sicily continental margin are representative of a jump of the deformation from the frontal area of the SFTB in the Sicily Channel to the inner sector in the Southern Tyrrhenian Sea. This study is in agreement with recent interpretations about a change in the subduction polarity in the central Mediterranean orogenic system, as a consequence of the ongoing collision of the African promontory with the thinned continental to oceanic sectors (Algerian and Tyrrhenian basins) of the European plate. The seismic activity associated with the north-vergent thrust could have implication for the assessment of the seismic risk in the Central Mediterranean and understanding of active structures in marine areas that could be responsible for tsunami hazard.

Geomorphological Tools for Mapping Natural Hazards.-- 12 pages, 7 figures, supplemental material https://doi.org/10.1080/17445647.2020.1866703.-- Software: The geomorphological main map and the Figures in the text were compiled using GLOBAL MAPPER, Surfer and Quantum-G GIS Software and redesigned to print with Adobe Illustrator, In this paper we present geomorphological hazard mapping of the San Vito Peninsula offshore (Sicilian margin of Tyrrhenian Sea), characterised by a very narrow continental shelf and a very dipping, tectonically active continental slope, no far from a seismogenic belt. The data set consists of morpho-bathymetric models achieved by means of multibeam survey and scattered high resolution seismic profiles. The morpho-bathymetric study highlighted some potential sites of geomorphological hazards, the most representative of which are: (i) two canyons developing from the upper slope off San Vito Cape down to the Erice basin; (ii) a dense network of small incisions across the upper slope; (iii) a very active landslide, developed onland and extending in the continental shelf close to the Scopello village. The geomorphological features that can generate submarine hazard are represented by: unstable sediment packages into canyon heads or along the upper slope; submarine canyons with regressive erosion; coastal landslides, With funding from the Spanish government through the ‘Severo Ochoa Centre of Excellence’ accreditation (CEX2019-000928-S)