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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 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

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 southern Sicilian coast represents an important contribution to Italian tourism, the Sicily Channel is an important communication path because at the top of its seafloor there are many pipelines, and submarine communication cables which are laid to carry signals, and which are very important to the minor islands. In this work, we are presenting results of the detailed geomorphological and seismostratigraphic analysis based on new very high-resolution dataset (multibeam and CHIRP) acquired during the ACUSCAL 2015 Cruise. We also used low resolution bathymetric and seismic data provided from online database (ViDEPI, GEBCO, EMODnet). This study allows us to reconstruct the tectonic volcanic mass movement and bottom current processes and to identify and map several relative geological elements (e.g. fluid escape structures, gravity driven deposits, volcanic morphologies) which were used to describe the geological setting of the study area. The latter is a small area (approx 100 km2) 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 between 10 and 350 m in depth. In the study area, the interaction of the sedimentary multilayer (e.g. Holocene sedimentary body, Messinian Evaporites) and the volcanic context (i.e. Graham Bank) with the tectonic activity (shallow and deep) creates a complex and highly geological framework hosting seafloor seepage. The main focus is the description of the fluid escape structures suggesting a possible model for the origin of the fluid and the mechanisms by which it is transferred to the seafloor. Another important aim is the reconstruction of the relationship between the deep tectonic structures and the fluid escape structures in the north-west Sicily Channel. Seafloor seepage is a widespread phenomenon in the global ocean forming important seafloor morphologies. It affects the global carbon cycle and provides the basis for abundant chemosynthetic organisms living in and on the seafloor. In this Ph.D. project, detailed investigation about the geological setting of such sites and the controlling factors for spatial and temporal distribution of the fluid escape structures were indispensable to understand the “fluid flow system functions” This work is a prime example of these interactions and their influence on seafloor seepage in the Western part of the Sicily Channel. Many pockmarks, mounds and some active seafloor seepages (i.e. hydro acoustic anomalies) have been identified and investigated using both stratigraphic information provided by AGIP/ENI Wells in conjunction with various geophysical data primarily multibeam and Chirp and secondarily multichannel seismic profiles and low resolution bathymetric data. The accurate bathymetric surveying by multibeam instruments allowed us to recognise several positive (mounds) and negative morphologies (pockmarks) linked at the fluid escape phenomena. The bathymetric data revealed an increase in size of the pockmarks with increasing distance to the elongated channel located in the central part of the study area and also that both pockmarks and mounds are isolated, aligned or clustered. CHIRP profiles imaged the presence of several recent faults affecting the Holocene sedimentary body and the occurrence of hydro-acoustic anomalies in the water column, located mainly at the top of the recognised volcanoes. The Multichannel seismic profiles that were correlated with the Agip/Eni wells, showed several acoustic anomalies (often from the Messinian Evaporites) and sub vertical normal fault systems, which affect gas migration in the sub-seafloor. In the western part of the study area, the Messinian Evaporites rise up to the seafloor with a jagged seafloor topography of the MES deforming the complete geological succession. Additionally, the volcanic context supplies large volumes of material to the seafloor, which are distributed as seamounts. The uplift of Messinian deposits concurrently with the formation of sub vertical normal faults leads to gases/fluids migration towards the seafloor forming a field at pockmarks of different sizes. In the eastern part, the rise up of volcanic material through the sub vertical normal faults leads to gases/fluids migration towards the top of the seamounts forming vertical plumes. The first study case of this work revealed a strong tectonic control on the development and distribution of the seepage features in the study area. The aim of the second study case of this work was the identification, description and classification of different examples of gravity driven deposits. The recognised gravity driven deposits in the study area using CHIRP and Multibeam data are: (i) soft-sediment depositional structures (SSDSs), (ii) rock falls and (iii) large debris avalanches. We however estimated the main pre-conditioning geomorphological factor, which could have induced sediment instability and the trigger mechanisms often linked to different geological processes. This second study case revealed that these geomorphological structures are characterised by a genesis probably linked to elevate slopes of the seabed as well as trigger different factors. Finally, mainly using the multibeam data and secondarily the CHIRP data, a cluster of seamounts that was recognised within the study area have been investigated and studied in detail. Their main dimensions and relative physical parameters have been measured and tabulated, allowing a morphometric and morphologic classification on the basis of their shapes. Several restrictive criteria were applied in order to be ceratin of their volcanic origin (conical shape with maximum height, basal ratio, aspect ratio) obtaining finally what can be classified as volcanic seamounts. These structures are very similar to submarine volcanoes described elsewhere on the seafloor. Some show at the top plain morphologies interpreted as marine terraces, others show a typical cone shape of the volcanoes one of which is characterised by a complex shape. On the basis of their morphological features these have been subdivided into three categories.

Active Fluid Seepage (AFS) at the seafloor is a global phenomenon associated with seafloor morphologies in different geodynamic contexts. Advances geophysical techniques have allowed geoscientists to characterise pockmarks, mounds and flares associated with AFS. We present a range of marine geological data acquired in the central Mediterranean Sea (northern Sicily continental margin, northwestern Sicily Channel and offshore the Maltese Islands), which allow us to identify AFSs. The AFSs are spatially distributed as clusters, aligned or isolated at different depths, ranging from few decametres offshore the Maltese Islands, up to 400 m offshore north Sicily and in the northwestern Sicily channel. Mounds have heights ranging from 2 to 15 m and form hummocky surfaces. Pockmarks with sub-circular planform shapes and U/V-shaped cross-sections are found in sizes ranging from 5 to 530 m. Gas flares occur on both the continental shelf and upper slope.

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.

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.