Search

The maps of the geohazard-related features of the North Sardinia continental margin produced by the Magic project (MArine Geohazard along Italian Coasts) are here presented. The maps were created on the base of morphobathymetric data obtained by with multibeam echo sounders. ThreCoNISMa, DSCG Università degli studi di Cagliari, Cittadella Universitaria Monserrato - S.P. Monserrato-Sestu, Monserrato (CA), Italye wide canyon systems, Castelsardo to the west, Lavezzi and Caprera to the east, originate from the continental shelf between the islands of Sardinia and Corsica and run toward the Sardinia Sea and the Tyrrhenian Sea, respectively. The canyons feature very wide and articulated heads, meandered sections of the main axis. The continental shelfhosts several coastal lithotomies, genetically related to late Quaternary sea-level oscillation and coastline migration. Furthermore, in the Bonifacio Strait, several bedform fields testify to the present-day activity of strong bottom currents. The main geohazard potential from the North Sardinia is related to the retreating of Castelsardo canyon heads, in offshore of Castelsardo and Asinara, which cuts the continental shelf reaching a few kilometers from the coast. [ABSTRACT FROM AUTHOR]

This paper accompanies the Maps of Geohazard features of the Cilento and the Calabro- Tyrrhenian continental margin in the southern Tyrrhenian Sea (Italy). The main geohazardrelated features were derived from extensive seafloor mapping through the collection of high-resolution multibeam data acquired during several oceanographic cruises. They encompass many fluids seepage features, fault scarps, landslides scars, gullies, channels, and canyons. Hazards related to coastal landslides and shelf-indenting canyons are very high in these sectors (especially in southern Calabria) due to active seismicity coupled with rapid uplift, high sedimentation rates and narrow or totally absent continental shelf, thus promoting a direct connection between steep slopes and coastal areas. In this setting, masswasting features can directly impact coastal or submarine infrastructures or indirectly create local tsunami waves, as observed in historical times. Moreover, this physiographic setting of the margin facilitates the transfer of marine litter toward deep-sea areas. [ABSTRACT FROM AUTHOR]

A previously unknown submerged volcanic field offshore western Sardinia (western Mediterranean Sea), has been identified based on swath bathymetric data collected in 2009, 2010 and 2013, and high-resolution seismic profiles collected in 2011 and 2013. About 40 conical-shaped volcanic edifices (maximum width of about 1600 m and maximum height of about 180 m) and several lava outcrops (up to 1,200 m wide) were recognized at 20 to 150 m water depth over an area of 800 km. The volcanic edifices are mainly eruptive monogenic vents, mostly isolated with a rather distinct shape, or grouped to form a coalescent volcanic body in which single elements are often still recognizable. High-resolution seismics enabled identifying relationships between the volcanic bodies and continental margin successions. The edifices overlie a major erosional surface related to the margin exposure following the Messinian salinity crisis, and are overlain by or interbedded with an early Pliocene marine unit. This seismo-stratigraphic pattern dates the volcanic activity to the early Pliocene, in agreement with the radiometric age of the Catalano island lavas (4.7 Ma) reported in earlier studies. The morphometry of the volcanic bodies suggests that cone erosion was higher at shallow water depths. Indeed, most of the shallow edifices are strongly eroded and flattened at 125 to 130 m water depth, plausibly explained by recurrent sub-aerial exposure during Pleistocene sea-level lowstands, whereas cones in deeper water are much better preserved. Volcanic vents and lava deposits, hereafter named the Catalano volcanic field (CVF), are emplaced along lineaments corresponding to the main directions of the normal fault system, which lowered the Sinis Basin and the western Sardinia continental margin. The CVF represents a volumetrically relevant phase of the late Miocene - Quaternary anorogenic volcanic cycle of Sardinia, which is related to the first stage of the extensional tectonics affecting the island since the late Miocene. [ABSTRACT FROM AUTHOR]

Multibeam echosounder data collected along the shelf of the western Sardinia margin (western Mediterranean Sea) revealed the occurrence of isolated dunes at a water depth of 35–40 m, linear and crescent-shaped sorted bedforms in the depth range of 43–70 m and crescent and irregular-shaped dunes at deeper sectors of the shelf, at a 73–87 m depth range. The morphodynamics of the seabed was analyzed by coupling multibeam backscatter data calibrated with ground truth sediment samples. The linear and crescent-shaped sorted bedforms in the depth range of 43–70 m are formed by a sequence of slight depressions characterized by coarse-grained sediments which alternated with elongated bodies, composed of finer sand, spaced ten to hundred meters apart and < 1 m high. The shelf sector, where the sorted bedforms occur, shows a terraced morphology, with planar sectors connected by gentle slopes. The sorted bedforms are generally oriented southwest to northeast, forming sequences of parallel crests which are located at the edge of the terraces. The analysis of very high-resolution seismic records suggests that the terraces are transgressive depositional sedimentary bodies forming prograding wedges. The analysis of the threshold hydrodynamic conditions for the motion of the sediment which forms the bedforms and the comparison of multibeam and sidescan sonar data collected over a 7-year time span revealed that the sorted bedforms migrate, and they are subjected to a regular forcing by the most severe storm waves from the NW. Sorted bedforms were not found in shallower water, where they are probably ephemeral features rapidly degraded by multi-directional waves and currents. At deeper sectors, > 70 m, wave energy is not strong enough to transport sediments and mud deposition prevails. We proposed an evolutionary model of the formation of prograding wedges and sorted bedforms off the western Sardinia shelf during the last sea-level rise. The landward migration of the shoreline subsequent to pulses of sea-level rise caused the deposition of prograding sandy wedges at different depths. Based on the present-day depth distribution, we can infer that the formation of persistent sorted bedforms over the edges of the terraces started after the sea level rose to a depth of 40 m over the seafloor where these bedforms occur. [ABSTRACT FROM AUTHOR]

Coastal erosion is a global problem which affects sandy and rocky shores worldwide. Coastal erosion can be triggered by several causes. Local processes can generate erosion hot spots, whereas at the global scale, the main forces are sea level rise, changes in storm climate and human interference. Beaches along the Mediterranean sea are strongly affected by coastal erosion. Recently, the Protocol on Integrated Coastal Zone Management in the Mediterranean (PAP/RAC 2007) recommended the prevention of erosion processes by restoring the natural adaptive capacity of the coast and by improving the knowledge on the state, development and impact of coastal erosion. In order to achieve the objective of the PAP/RAC protocol, we characterized 24 sandy beaches along ~270 km of the western coastline of the Sardinia island (western Mediterranean). Grain size and mineralogy of the foreshore sediments were analyzed and the intertidal elevation/bathymetric profile were measured using the Differential Global Positioning System. Aerial photos were used to identify the shoreline configuration, the number of bars and morphodynamic features. A digital elevation model (DEM) of the adjacent shelf was produced and acoustic backscatter, grab and box-corer sediment samples were collected in order to characterize the seafloor and to identify the substrate lithology, particularly the distribution of sandy sediments. The investigated coastline is characterized by linear, multibarred beaches and wide transgressive dune fields formed by terrigenous and coarse sand. These linear beaches are alternated with embayed beaches which locally show a mixed terrigenous/bioclastic carbonate composition. Large sandy bodies were found in the inner shelf, often forming dune fields which were uncovered by mud drapes. A database was created to facilitate the characterization of the beach systems along the studied coastline and adjacent inner shelf. It is anticipated that the database will be used by policy makers in support of the implementation of coastal erosion management strategies. [ABSTRACT FROM AUTHOR]

De Falco, G., Budillon, F., Conforti A., De Muro, S., Di Martino G., Innangi, S., Perilli, A., Tonielli, R., Simeone, S. 2014. Sandy beaches characterization and management of coastal erosion on western Sardinia island (Mediterranean sea). In: Green, A.N. and Cooper, J.A.G. (eds.), Proceedings 13th International Coastal Symposium (Durban, South Africa), Journal of Coastal Research, Special Issue No. 70, pp. 395-400, ISSN 0749-0208. Coastal erosion is a global problem which affects sandy and rocky shores worldwide. Coastal erosion can be triggered by several causes. Local processes can generate erosion hot spots, whereas at the global scale, the main forces are sea level rise, changes in storm climate and human interference. Beaches along the Mediterranean sea are strongly affected by coastal erosion. Recently, the Protocol on Integrated Coastal Zone Management in the Mediterranean (PAP/RAC 2007) recommended the prevention of erosion processes by restoring the natural adaptive capacity of the coast and by improving the knowledge on the state, development and impact of coastal erosion. In order to achieve the objective of the PAP/RAC protocol, we characterized 24 sandy beaches along ~270 km of the western coastline of the Sardinia island (western Mediterranean). Grain size and mineralogy of the foreshore sediments were analyzed and the intertidal elevation/bathymetric profile were measured using the Differential Global Positioning System. Aerial photos were used to identify the shoreline configuration, the number of bars and morphodynamic features. A digital elevation model (DEM) of the adjacent shelf was produced and acoustic backscatter, grab and box-corer sediment samples were collected in order to characterize the seafloor and to identify the substrate lithology, particularly the distribution of sandy sediments. The investigated coastline is characterized by linear, multibarred beaches and wide transgressive dune fields formed by terrigenous and coarse sand. These linear beaches are alternated with embayed beaches which locally show a mixed terrigenous/bioclastic carbonate composition. Large sandy bodies were found in the inner shelf, often forming dune fields which were uncovered by mud drapes. A database was created to facilitate the characterization of the beach systems along the studied coastline and adjacent inner shelf. It is anticipated that the database will be used by policy makers in support of the implementation of coastal erosion management strategies. [ABSTRACT FROM AUTHOR]

The Bulgheria canyon-fan system in the eastern Tyrrhenian Sea displays well-developed, small-scale, fluvial-like features and has formed alongside the northern slope of the Sapri peri-Tyrrhenian basin. This study reveals, for the first time, the morphology and course of the present-day system as well as the buried elements based on a Digital Terrain Model and high-resolution seismic profiles interpretation. Two adjacent canyons (Infreschi and Luna) originate in the Cilento outer shelf at a short distance from each other and feed an intraslope basin fan through two main sub-parallel channels that run about 12 and 8 km, respectively. Channel and levee development seems to be controlled primarily by the local slope gradient and by Coriolis forces that induce a faster vertical growth of the right-side features, as is often observed in the Northern Hemisphere. Centrifugal forces, on the other hand, have induced episodic flow-stripping at the meander loops and bends, causing local destruction of the main channel levees rather than new levee growth at the outer bends. Overbank deposits are associated with overspill turbidite deposition in the mid fan where a topographic constraint occurs, whereas large-sediment, low-angle wave fields are mainly developed on the outer fan. Buried features and relict morphologies suggest that the Infreschi channel experienced at least two phases of re-incision since the final stages of the middle Pleistocene. Local re-adjustment of outer lobe growth due to channel avulsion and meander abandonment is possibly a consequence of relative base-level fluctuations. The sedimentary record of the mid and outer fan includes outrun mass wasting deposits from extensive failures of the Sapri slope. Indeed, a marked scar is present on the eastern side of the modern outer lobe that indicates the persistency of mass flow passages up to recent times. In addition to the environmental factors that are currently considered to cause canyon formation on the shelf margin, this study proposes the possibility that the head canyon branch close to the mainland was incised by massive and persistent underground freshwater flow from the adjacent aquifer when the sea-level was lower than at present. [ABSTRACT FROM AUTHOR]

High-resolution bathymetry provides critical information to marine geoscientists. Bathymetric big data help characterise the seafloor and its benthic habitats, understand sedimentary records, and support the development of offshore engineering infrastructures. From September 27th to October 20th, 2022, the new CNR Research Vessel GAIA BLU explored the seafloor of the Naples and Pozzuoli Gulfs, and the Amalfi coastal area (Tyrrhenian Sea, Italy) from 50 to more than 2000 m water depth, acquiring about 5000 km2 of multi beam echosounder data. This area is particularly vulnerable to abrupt changes driven by the dynamics of several volcanic complexes, active in the area, and by human-induced impacts reflecting the proximity to the highly populated and touristic coastal area of Naples and nearby famous islands. For these reasons, the seafloor of the area needs to be known and constantly monitored. The digital bathymetric data previously available are restricted to the shallow highly dynamic area of the Gulf of Naples and appear fragmented as they were acquired in successive years, with different goals thereby using a variety of devices, with markedly different spatial resolutions. In this paper, we present bathymetric maps of the Gulf of Naples and adjacent slope basins at unprecedented resolution using three state-of-the-art multi beam echosounders. These high-resolution data highlight the technological advances of geophysical surveys achieved over the last 20 years and contribute to assessing the most dynamic areas where changes in the seafloor over time can be quantified. The new digital multi-resolution bathymetric products are openly accessible via Marine Geosciences Data System MGDS (refer to section Data Availability, Table 8, for datasets and products DOIs), perfectly matching the FAIR (Findable, Accessible, Interoperable and Reusable) and Open Science Principles. [ABSTRACT FROM AUTHOR]

We present a seabed map around Lampedusa, the largest island of the Pelagie Islands Marine Protected Area (Italy, western Mediterranean). The seafloor was mapped using bathymetry and backscatter multibeam systems along with an underwater camera for direct observations and ground truthing, from the coastal area to about 50 m depth. The map was produced to monitor the present-day distribution of thePosidonia oceanicameadows around the Island.P. oceanicais the most important endemic seagrass species of the Mediterranean Sea and it can form meadows or beds extending from the surface to 40–45 m depth. These meadows provide habitat for a large marine community, thus increasing biodiversity of the coastal zone, stabilizing sediments and reducing coastline erosion. The seagrass meadows are susceptible to regression in response to specific impacts, thus their presence and abundance is an indicator of the overall environmental quality of the coastal zone. Recently, within the Marine Strategy Framework Directive (2008/56/EC),P. oceanicahas been selected as an indicator of the Good Environmental Status for marine areas. Consequently, the Pelagie Islands Marine Protected Area launched a project to assess the conservation status and map the distribution ofP. oceanicameadows. The resulting 1:15,000 scale map includes information about the Mediterranean seagrass and the distribution of five acoustic facies reflecting hard lithologies and soft substrates. The Lampedusa seabed map provides new information, which contributes to the development of a detailed benthic habitat map and a more comprehensive maritime spatial planning of this Marine Protected Area. [ABSTRACT FROM AUTHOR]

Abstract: Long-term change of Earth's magnetic field (palaeomagnetic secular variation, PSV) during much of the last approximately 120ka was recorded in cored sediment from the slope margin of the eastern Tyrrhenian Sea. The PSV record has been correlated to master curves of global palaeomagnetic field intensity and PSV records for western Europe. Tephrochronology and radiometric dating (14C and 40Ar/39Ar) have also been used to constrain the age of the PSV record. The combination of the new data with prior PSV and petrophysical data from the area provides a chronological framework for geological events such as large-scale submarine slumps, stratigraphic gaps and short-term changes in deposition rate on the continental margin. These latter changes are linked to the combined action of relative sea-level oscillations, climate events, and consequent variations in land exposure through time. Moreover, new data concerning the thickness and dispersal of Campanian Plain pyroclastic deposits in the marine setting enable volcanic-hazard evaluation. Finally, a pyroclastic deposit (tephra X-6) found offshore in the Southern Campanian marine environment was 40Ar/39Ar dated for the first time at 108.9±1.8kaBP. [Copyright &y& Elsevier]

Abstract: Morphological and seismic–stratigraphic features of the Augusta Bay (offshore eastern Sicily) have been characterized by means of Sub-bottom Chirp profiles, Multibeam data and Side Scan Sonar images, covering an area of about 110km2. The marine data set was combined to mainland stratigraphy, derived from coastal boreholes and geological maps, to achieve a land–sea correspondence of main morpho-structural and stratigraphical features. The study area is located in the western sector of the Ionian Sea which represents a key area to reconstruct the geological parameters that control the processes of convergence between Africa and Europe in the Mediterranean. In particular, the area of interest draws the attention for problems concerning high seismicity and environmental pollution from oil and chemical industries. The Augusta Bay offshore displays a marked variability of morphologies and seismic–stratigraphic characters, related to the influence of both large-scale geological processes and local variables. It consists of an irregular surfaced narrow shelf, generally tracing out the shape of the relative coastline seaward bounded by a steep continental slope. This latter is deeply engraved by gullies and shows evidences of recent withdrawal, favored by the occurrence of structural lineaments. The Augusta offshore reflects the corresponding on-land geological pattern, being characterized by a central basinal area filled with Pleistocene–Holocene successions, bounded by two relieved sectors corresponding to the seaward prosecution of the Mt. Tauro and Magnisi–St. Panagia horsts, where the Miocene substratum outcrops. The seismic–stratigraphic architecture of the basinal area not only is the result of sea-level variations related to the Late Pleistocene sea-level fall and subsequent transgressive phase, responsible for the formation of a main angular unconformity, but also depends on pre-existing substratum arrangement, which leads to a wide lateral facies variability, on short distances. Morphological and seismic–stratigraphic evidences outline the presence of structural lineaments whose orientation is consistent with that of the on-land sectors. Slight movements are testified by the dislocation of recent sedimentary covers, pointing to active tectonic processes during Holocene. Such vertical movements are also responsible for a southward differential subsidence of the basinal area, whereas the proximal portion of the shelf seems to be strictly connected to the uplifting emerged sectors. This evidence is consistent with the recognition of recently active tectonic structures where the distal offshore represents the down-faulted sector. Our results, providing a detailed knowledge of the submerged sector of a highly populated area, affected by high seismicity and environmental pollution risk may significantly contribute to an appropriate management of the area in the next future. [Copyright &y& Elsevier]

Mapping of coralligenous banks was carried out along the continental shelf of the northern and western margin of Sardinia Island (Italy, western Mediterranean Sea) in the context of the European Marine Strategy Framework Directive (MSFD, 2008/56/EC). Coralligenous banks are bioconstructions produced by calcareous coralline algae. Seafloor mapping was carried out through multibeam echosounder surveys and video transects, using a Remote Operating Vehicles (ROV), in areas not formerly explored. A high-resolution digital model of the seabed (DTM) was obtained from multibeam data. A total surface of 436 km² of sparse patches of coralligenous banks was mapped in the depth range ~40-160 m. A final map of coralligenous habitat distributions along the western and northern continental shelf of Sardinia (scale 1:250,000) was produced. The base-map is formed by the shaded DTM of the seabed. Other mapped features include the edge of the continental shelf and the distribution of rocky seabed. [ABSTRACT FROM AUTHOR]

In this paper we present the seabed maps of the shallow-water areas of Lampedusa and Linosa, belonging to the Pelagie Islands Marine Protected Area. Two surveys were carried out ("Lampedusa 2015" and "Linosa 2016") to collect bathymetric and acoustic backscatter data through the use of a Reson SeaBat 7125 high-resolution multibeam system. Ground-truth data, in the form of grab samples and diver video-observations, were also collected during both surveys. Sediment samples were analyzed for grain size, while video images were analyzed and described revealing the acoustic seabed and other bio-physical characteristics. A map of seabed classification, including sediment types and seagrass distribution, was produced using the tool Remote Sensing Object Based Image Analysis (RSOBIA) by integrating information derived from backscatter data and bathy-morphological features, validated by ground-truth data. This allows to create a first seabed maps (i.e. benthoscape classification), of Lampedusa and Linosa, at scale 1:20 000 and 1:32 000, respectively, that will be checked and implemented through further surveys. The results point out a very rich and largely variable marine ecosystem on the seabed surrounding the two islands, with the occurrence of priority habitats, and will be of support for a more comprehensive maritime spatial planning of the Marine Protected Area. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is a miniature ocean ideal to test the response of marine ecosystems to amplified orbital and suborbital climate changes. Here we present coccolith data from a Sardinia Channel gravity core (Arcose C_33) analysed over the last 145,000 years, with a mean resolution of about 900 years. The study highlights that regional phytoplankton assemblages underwent significant modifications between the penultimate glacial and the last interglacial, as well as between the last glacial and the Holocene. The N ratio palaeoproductivity index suggests reduced productivity levels and the development of a deep nutricline during the last interglacial and the Holocene. Within the last glacial period, many taxa exhibit abundance fluctuations that parallel oscillations in δ 18 O values of Globigerina bulloides tests. Heinrich events and stadials seem to be associated with drops in primary productivity levels, as already observed in the Alboran Sea and the Sicily Channel. A total of 19 ecobioevents were identified in the Sardinia Channel sediments, including abundance fluctuations of Emiliania huxleyi > 4 μm, Florisphaera profunda and Gephyrocapsa oceanica . The comparison of events across the Mediterranean Sea suggests that traceability applies to the Sicily Channel, Balearic and Tyrrhenian Seas, supporting the adoption of a common ecobiostratigraphic scheme. Less certain is the correlation with the Alboran Sea, although peaks of Helicosphaera carteri and Syracosphaera histrica during Heinrich events and stadials suggest similar nutrient dynamics in response to suborbital climatic variations in the Sicily Channel, southern Tyrrhenian and Alboran Seas. The traceability of events within eastern Mediterranean cores is strongly limited, possibly due to different physico-chemical properties and nutrient dynamics. [ABSTRACT FROM AUTHOR]

• Study on the electromagnetic field onboard to evaluate EMI in critical points. • The onboard acquisition systems are potentially affect by electromagnetic noise. • A preliminary electromagnetic screening is advisable to optimize the ship cabling. When performing oceanography measurements, it is critical to assess the presence of the noise sources that could affect the measured data and lead to wrong interpretation of the results. This paper report the result of an oceanography survey conducted by ISMAR-CNR, Naples, in the north-eastern marine sector of the Ischia Island and assess the influence of EMI on the measured results. The analyzed measurements of the Electric and Magnetic fields showed values of the E up to 0.82 V/m and of B up to 85 μT. By assuming a standard conductor, an inductance L up to 47 Ω on the cable corresponding to an induced electromotive force of 1184 mV was calculated. Also the experimental data show the EMI increase in site where the Pearson index correlation is higher. The results demonstrate that in an oceanographic survey planning, a preliminary electromagnetic screening is advisable to optimize the measurement setup. [ABSTRACT FROM AUTHOR]