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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.

The Maltese Islands are intersected by two major fault systems associated with two diverse rifting episodes affect the islands. The first and most widespread system is Early Miocene to mid-Pliocene in age, and consists of faults that are orientated ENE-WSW. The most distinct of these faults is the Great Fault (known also as the Victoria Lines Fault). The younger system of faults (Late Miocene-Early Pliocene) is still active and consists of faults striking NW to SE that often cross-cut the first generation of faults. The most extensive of these faults is the Maghlaq Fault, located along the southern coastline of the Maltese Islands., peer-reviewed

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 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.

In this study we present the results of a seismic-stratigraphic analysis of sub-bottom profiles in the north-westernmost area of the Malta Plateau in order to define the depositional mechanisms for the upper Quaternary sequences. During this interval the morphology of the Malta Plateau was characterized by a ramp and bathymetries not exceeding 200 m. Two major unconformities, related to MIS 6 and MIS 2 (the latter corresponding to the Last Glacial Maximum, LGM), characterize the upper Quaternary sequences. The geometries of the recognized seismic units indicate as depositional mechanisms were controlled by subsidence and sea-level fluctuations. In detail, deposits related to the last glacial event were recognized through their seismic pattern and have been interpreted as formed by the interaction between tide and wave dynamics. Contrary to the northern Sicilian continental margin, in the Malta Plateau ramp no LGM-related lowstand prograding wedge was recognized due to the absence of an effective shelf edge. It is considered as a consequence of the morphology and the dominant deposition processes in the Malta Plateau. Afterwards the ramp morphology allowed a rapid drowning of the Malta Plateau instead with the formation and preservation of transgressive deposits revealed as bedforms. The highstand deposits appear as prograding bodies and have been classified as infralittoral prograding wedge.

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)

We present the results of an integrated geomorphological and seismo-stratigraphic study based on high resolution marine data acquired in the north-western Sicilian continental margin. We document for the first time five contourite drifts (marked as EM1a, EM2b, EM2, EM3a, and EM3b), located in the continental slope at depths between ca. 400 and 1500 m. EM1a,b have been interpreted as elongated mounded drifts. EM1a,b are ca. 3 km long, 1.3 km wide, and have a maximum thickness of 36 m in their center that thins northwards, while EM1b is smaller with a thickness up to 24 m. They are internally characterized by mounded seismic packages dominated by continuous and parallel reflectors. EM2 is located in the upper slope at a depth of ca. 1470 m, and it is ca. 9.3 km long, more than 3.9 km wide, and has a maximum thickness of ca. 65 m. It consists of an internal aggradational stacking pattern with elongated mounded packages of continuous, moderate to high amplitude seismic reflectors. EM2 is internally composed by a mix of contourite deposits (Holocene) interbedded with turbiditic and/or mass flow deposits. EM1a,b and EM2 are deposited at the top of an erosional truncation aged at 11.5 ka, so they mostly formed during the Holocene. EM3a,b are ca. 16 km long, more than 6.7 km wide, and have a thickness up to 350 m. Both EM2 and EM3a,b have been interpreted as sheeted drift due to their morphology and seismic features. The spatial distribution of the contourite drifts suggests that the drifts are likely generated by the interaction of the LIW, and deep Tyrrhenian water (TDW) on the seafloor, playing an important role in the shaping this continental margin since the late Pleistocene-Holocene. The results may help to understand the deep oceanic processes affecting the north-western Sicilian continental margin.

A high resolution seismic stratigraphic study of the western edge of the Malta Plateau (central Mediterranean Sea) was conducted to reconstruct the depositional mechanisms of the shelf-slope system since the end of the Messinian salinity crisis (MSC; 5.3 Ma). The accurate interpretation of a large grid of variable-resolution seismic reflection profiles (multichannel and Sub Bottom) allows us to identify and map a Plio-Quaternary sedimentary sequence overlying the Messinian evaporites. The stratal pattern of this sequence is the result of a clinoform prograding system that constitutes the internal structure of a sedimentary shelf developed in a ramp about 2° slope with bathymetries that do not exceed 200 m. This type of shelf is a physiographic feature where the shelf edge separates littoral from bathyal realms, differing from the definition of continental shelf that implies the presence of a continent-ocean margin. The evolution of the western edge of Malta Plateau differs from adjacent sectors. Unlike to the nearby Gela Basin, where the Plio-Quaternary sedimentary sequences were affected by the thrusting of the Sicilian-Maghrebian chain until Middle Pleistocene, in the Malta Plateau the post-Messinian sedimentation was mainly controlled by subsidence and sea level fluctuations. In particular, the Malta Plateau represents a back bulge depozone where moderate fluvial sediment supply together with continuous subsidence favoured the progradation of the upper Pliocene-Pleistocene shelf-slope system at bathymetries not exceeding 200 m.

Graham Bank is a dominant physiographic element of the NW Sicily Channel (central Mediterranean Sea), affected in the last 100 years by numerous well-documented volcanic eruptions. We present the first results of a geomorphological study where the Graham Bank region in the depth interval 7–350 m was mapped for the first time with multi-beam echosounder and high-resolution seismic and multi-channel seismic reflection profiles. We describe in high resolution the detailed geomorphological features of Graham Bank, and how the superficial expression of different process and dynamics occurring in the sub-seafloor evidence volcanic and tectonic controls on seafloor morphology across a relatively small area. The north-eastern part of the study area is dominated by seamounts with heights ranging from 97 to 152 m and auxiliary small cones, reaching heights of 2–10 m, on the whole forming a hummocky surface. In this region, fluid seepages are an important expression of the volcanic processes affecting the study area. The western region comprises a flat seafloor covered by Upper Pleistocene-Holocene outer shelf sedimentary deposits; here aligned mounds and pockmarks are predominantly oriented NW–SE or NNW-SSE, running parallel to the main structural trend of the Sicily Channel. The pockmarks have sub-circular planform shapes and U-shaped cross-section and different depths and mean axis lengths. Numerous Mass Transport Deposits (MTDs) are distributed across the study area. Graham Bank is 45 km from the coast of Sicily and is intersected by submarine cables. Consequently, the mapped volcanic seamounts, pockmarks and MTDs could pose a significant economic risk to the submarine cables.