GM6.7

An open access database containing raw data of Last Interglacial sea-level proxies for the Western Mediterranean has been compiled by reviewing hundreds of original published papers in accordance with the WALIS template (https://warmcoasts.eu/world-atlas.html). WALIS allows collecting both the relative sea-level (RSL) indicators and ages data in a standardized format. Ca. 360 sea-level index points for the coasts of Spain, France, Italy, Albania, Algeria and Morocco have been included in the database. The sea-level index points of the database are related to ca. 350 samples dated by a wide range of dating techniques, e.g., U-series, Amino Acid Racemization, Luminescence (Tl/OSL) and Electron Spin Resonance methods or chronostratigraphically correlated to marine deposits bearing P. latus and “Senegalese fauna”. In fact, for some areas of the Mediterranean Sea, the “Senegalese fauna” is indicative of the MIS 5e.

Among the eleven types of sea-level indicators of our database, the majority of them are represented by marine terraces, beach deposits (or beachrocks), and tidal notches. Whenever the relationship between the RSL indicators and the former sea-level could not be quantified, such indicators have been considered as marine or terrestrial limiting points. An indirect age of the tidal notches has been provided by correlation with the nearby dated deposit. In the case no precise elevation information has been reported by the Authors, the elevation error of RSL datapoints has been reassessed in the 20 % of the elevation value, more a 5% if the sea-level datum was lacking in the scientific papers we have reviewed.  Overall, the quality of each RSL datapoints and the associated age have been ranked in a 0 to 5 scale score according to Rovere et al., (2020).

References

Rovere, A., Ryan, D., Murray-Wallace, C., Simms, A., Vacchi, M., Dutton, A., Gowan, E., 2020. Descriptions of database fields for the World Atlas of Last Interglacial Shorelines (WALIS) (Version 1,0). Zenodo. https://doi.org/http://doi.org/10.5281/zenodo.3961544

How to cite: Cerrone, C., Vacchi, M., Fontana, A., and Rovere, A.: The Last Interglacial Sea Level database for the Western Mediterranean, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13192, https://doi.org/10.5194/egusphere-egu21-13192, 2021.

Vast areas of the shallow Adriatic shelf were exposed at the time of the Last Glacial Maximum lowstand. This enabled formation of lakes, river valleys and river floodplains that were submerged during the Holocene transgression. Here we present a study of the karst estuary of the Krka River located in central Dalmatia on the eastern Adriatic coast. The Krka River creates a 23 km long estuary extending north from the Šibenik Channel, over the Prokljan Lake, up to the tufa waterfall Skradinski buk. We used high resolution acoustic methods including sub-bottom profiler (SBP) coupled with multibeam echo sounder (MBES) (MBES bathymetry and MBES backscatter) and side-scan sonar (SSS) to investigate the submerged karst river valley and lake system that existed before the Holocene relative sea level rise. A total of 70 km of SBP profiles and a point cloud of 241 991 638 points in the area of 6.2 km² were collected during the surveys. Water depth ranges from 5 m b.s.l. in the most northern part of the study area, to 25 m b.s.l. in the southern part of the Prokljan lake.

To create a better geomorphological and geological classifications of the seabed, we made a network of 36 ground truthing stations where we sampled sediments with Van Veen grab sampler and obtained underwater images. Sediment samples were analyzed for grain size, bulk density, carbon and nitrogen concentrations, as well as mineralogical XRD analysis and magnetic susceptibility. We combined gathered data with GIS classification tools to create accurate seabed maps of the area. Our results also showed that well-defined submerged river canyon in the Prokljan Lake area was filled with three sedimentary units: fluvial, brackish and marine. Quaternary sediment thickness is up to 15 m. Seabed geomorphology of the investigated area is characterized by many submerged tufa barriers. They are similar to present barriers upstream of the Skradinski buk waterfall. These unique karst geomorphological features, that grow as algae and mosses are encrusted by carbonate, enabled formation of lakes, as well as prevented a marine flooding during the Holocene sea-level rise. The depth of each barrier (4.5 to 12 m b.s.l.), in connection to the onset of marine sedimentation within the estuary, can be used as an indicator of sea level. Barriers are emphasized on the MBES backscatter data as strong reflectors. Grain size of sampled sediments ranges from poorly sorted sand and gravel on underwater barriers to fine silt sediments in the deeper parts of Prokljan Lake. Larger sediment size on barriers is caused by tufa debris while fine silt is sedimented in the deeper parts of the basin. Grain size results vary for different geomorphological provinces, allowing for a more precise (GIS) classification and description of the seabed.

This work was supported by the Croatian Science Foundation Project “Sediments between source and sink during a late Quaternary eustatic cycle: the Krka River and the Mid Adriatic Deep System” (QMAD) (HRZZ IP-04-2019-8505).

How to cite: Hasan, O., Miko, S., Brunović, D., Šenolt, N., Šparica Miko, M., and Ilijanić, N.: Seabed geomorphology of the Prokljan Lake – a Krka River estuary on the eastern Adriatic coast (Dalmatia), EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-11320, https://doi.org/10.5194/egusphere-egu21-11320, 2021.

South-eastern Sicily is among the most seismically active areas of the central Mediterranean. As such, it is marked by a high level of crustal seismicity producing major earthquakes (up to Mw ∼7), and consequent several earthquake-generated tsunami, which have affected the Ionian coast of South-eastern Sicily in historical times. These tsunami events left geomorphic imprints such as large boulders or high-energy deposits along the Sicily coasts. In Ognina, a small town located 20 km south of Siracusa, high-energy deposits were correlated with three tsunami events that struck this coast on 21 July 365 Common Era (CE), 4 February 1169 CE, and 11 January 1693 CE. The deposits are detected in the inner part of a narrow channel, that is thought to have funnelled the tsunami flow energy. In this work, numerical models have been performed to simulate the tsunami impacts, considering the most probable tsunamogenic sources described in literature and integrating them with the past sea-level positions. To this end, we used Delft Dashboard, Delft 3d-FLOW and XBeach. A reconstruction of the past topography of Ognina coast was performed through geological and historical information, in order to model the tsunami wave propagation in the ancient landscape. Geological evidence with model results, under different scenarios, allow us to benchmark fault location and displacement scenarios. Modelling results indicate that the 1693 tsunami event was stronger than others impacting the Ognina area, determining significant inland flooding in the narrow channel. Moreover, simulations show that the most probable tsunamogenic sources of 1693 and 1169 tsunami events could be attributed to Western Fault dislocations occurred off-shore of Ognina area, rather than the other tsunamogenic sources described in literature, located off-shore of Catania and Siracusa. Modelling of 365 AD event shows a long period for the tsunami wave that determined the sedimentation on the lower units in the outcrop. For each of the three tsunami events, models of high-energy deposition match with position and thickness of high-energy layers detected in the field. The results of this study show how a combined approach between geological evidence and tsunami modelling could be a suitable tool for the attribution of tsunami deposits connected to specific tsunamogenic sources.

Keyword: tsunami; earthquake; faults; flooding; sea-level

How to cite: Scardino, G., Rizzo, A., De Santis, V., Kyriakoudi, D., Rovere, A., Vacchi, M., and Scicchitano, G.: On the origin of multiple tsunami inundation of the archaeological site of Ognina (Sicily): Numerical models and field geological data, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-8591, https://doi.org/10.5194/egusphere-egu21-8591, 2021.

The study of environmental changes in coastal areas provide useful information for past conditions and constitute a powerful tool for accurate palaeogeographic reconstructions. Several coastal landforms are present on the coastal zone, with different response to environmental change. Coastal wetlands and lagoons are particularly sensitive to local paleoenvironmental changes and provide an excellent opportunity to reconstruct the evolution of the coastal zone evolution and the sea level changes. In this context, the aim of this work is to elucidate the coastal evolution of Psatha bay, Alkyonides Gulf, Greece, through coastal drillings and geomorphological sea level markers.

The study area is located at the eastern end of Corinth Gulf, in the Gulf of Alkyonides. Psatha is bounded by active neotectonic structures, which have been a determining factor in its development. In this work we adopt a multiproxy approach through the study of coastal drillings and beachrocks, and micro-topography constructed after photogrammetric processing of very high resolution and accuracy images acquired by several Unmanned Aerial System flights. We coupled detailed beachrock mapping, microstratigraphic analysis and luminescence dating to study beachrock outcrops found up to 1 m above the present sea-level. For the palaeoenvironmental reconstruction, multiproxy analyses were undertaken, which included sedimentological analysis of the core, paleontological analysis of macrofauna and microfauna and radiocarbon dating. The results of this work will contribute to the better understanding of a coastal site in a tectonically active area and the relative sea level changes.

This research is co-financed by Greece and the European Union (European Social Fund- ESF) through the Operational Programme «Human Resources Development, Education and Lifelong Learning» in the context of the project “Reinforcement of Postdoctoral Researchers - 2nd Cycle” (MIS-5033021).

How to cite: Karkani, A., Saitis, G., Tsanakas, K., Evelpidou, N., Karymbalis, E., Vassilakis, E., Drinia, H., and Batzakis, D.-V.: Palaeogeographic evolution and sea level changes of a tectonically active area: the case of Psatha, Alkyonides Gulf, Greece, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-13236, https://doi.org/10.5194/egusphere-egu21-13236, 2021.

The coastal vulnerability along the Mediterranean coasts is increasing, especially in response to the occurrence of tropical-like events, known as Medicanes, which have become more intense than in the past. A peculiar case was the impact of Medicane Zorbas occurred in September 2018 along the coasts of Southeastern Sicily, where it caused inland flooding and damages to the socio-economic activities. We reconstructed Zorbas effects through post-event geomorphological surveys, interviews to direct witness and analyses of video recorded by surveillance systems or found in the social media. These data allowed to assess the flooding extent on seven coastal sectors located between Thapsos Peninsula and Marzamemi. Flooding caused by Zorbas appears to be greater than those surveyed after the main seasonal storms occurred in the areas from 2015 to 2019, but comparable with the flooding generated by Medicane Qendresa that impacted the southeastern Sicily in 2014. Waves propagation modelling was performed through Delft 3D for the main marine extreme events occurred in the area since 2005, and analyses of data recorded by tide gauge of Catania and Porto Palo di Capo Passero and Malta since 2008 let us to hypothesize that Medicanes generate greater flooding than seasonal storms because they can induce higher and longer surge along the coastline. Collected data indicate that surge generated by Zorbas reached a maximum value between about 0.8 m and 1.2 m above mean sea level (msl) along the coast of southeastern Sicily. Results highlighted the need to better evaluate the coastal hazard related to the propagation of Medicanes, especially in the context of future climate change, when these events could be characterized by a longer duration and a greater intensity than the present, such to cause greater flooding and damage to the coastal areas.

Keywords: coastal flooding; storm wave; storm surge; Medicane; vulnerability.

How to cite: Scardino, G., Scicchitano, G., Rizzo, A., Monaco, C., Piscitelli, A., Milella, M., Francesco, D. G., and Mastronuzzi, G.: Comparing impact effects of common storms and Medicanes along the coast of Southeastern Sicily, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-10027, https://doi.org/10.5194/egusphere-egu21-10027, 2021.

The Tel-Dor embayment located along the Carmel coast provides a valuable opportunity to study environmental and human interaction due to its protecting geomorphic properties that are unique for the generally linear Israeli coast. Interpretations of seismic profiles collected from transects across the bay show five seismic units that have been correlated to dated and well-analyzed sediment units in coastal cores, enabling a detailed deep time reconstruction of the coastal system over the last ~77 ka. The earliest borehole deposits are low-stand aeolian followed by terrestrial sediments including wetland remains that were subsequently flooded by the mid-Holocene transgression. Evidence of the earliest human settlement submerged Pottery-Neolithic (8.25-7 ka) remains, found immediately above the wetland deposits landward of a submerged aeolianite ridge at the mouth of the bay. The wetland deposits and Pottery-Neolithic settlement remains are at present buried by coastal sand recording middle Holocene sea-level rise and thus, suggesting that these coastal communities were displaced by sea-level transgression ca. 7.6–6.5 ka. The sedimentological and archaeological evidence identified in the stratigraphical sequence of the sheltered bay is a good example of better understanding the essential environmental changes on the shallow shelf and the coastline migration especially in bays and the human settlement adaptations to these changes. This high-resolution reconstruction based on seismic methods in the shallow water and core analysis on land combined with detailed archaeological data from the studied area provides an important addition to the puzzle of the Mediterranean story, the cradle of Western Civilizations.

How to cite: Shtienberg, G., Gadol, O., Levy, T., Norris, R., Rittenour, T., Yasur-Landau, A., Tamberino, A., and Lazar, M.: Late Pleistocene to Holocene shallow marine – coastal changing environments and human interaction in the South Bay of Dor, Israel, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-338, https://doi.org/10.5194/egusphere-egu21-338, 2021.

The EMODnet Geology project is delivering integrated geological map products that include seabed substrates, sedimentation rates, seafloor geology, Quaternary geology, geomorphology, coastal behaviour, geological events such as submarine landslides and earthquakes, and marine mineral occurrences. The newest addition to the EMODnet Geology project are map products reflecting submerged landscapes of the continental shelf which have been compiled across European Seas for the first time.

Sea level is known to have fluctuated by more than 100 m over repeated glacial cycles, resulting in recurring exposure, inundation and migration of coastlines not only across Europe but worldwide. Landscape response to these changes in sea level, and the preservation of these features on continental shelves around Europe, are an invaluable resource for improving our understanding of human history and environmental change over geological time, while also providing data for potential use in examining future sea-level rise scenarios.

Recent advances in both data acquisition and availability over the last two decades has enabled researchers to more accurately reconstruct the extent and dynamics of fluctuating palaeocoastlines. High-resolution multibeam bathymetry and sub-bottom seismic data, in particular, have resulted in a step change in our understanding of palaeoshorelines and other traces of the original landscape topography and sediments.

The dedicated work package aimed to compile and harmonize available information on submerged landscape features by integrating existing records of palaeoenvironmental indicators with interpretations of geomorphology, stratigraphy and type of sediment. The fully attributed GIS layer comprises more than 10,000 features representing 26 classes of submerged landscape and palaeoenvironmental indicators ranging from mapped and modelled palaeocoastlines, evidence for submerged forests and peats, thickness of post-Last Glacial Maximum sediments and submerged freshwater springs across all European seas. These data will be used to underpin palaeogeographic reconstructions at 20,000, 9000, and 6000 ka BP during the fourth phase of the project (2019-2021).

This paper will present the ongoing data compilation and harmonisation process, current work on regional palaeogeographic reconstructions, primarily efforts towards creation of a pan-European 20,000 ka BP (Last Glacial Maximum) palaeogeographic reconstruction, and summarise key challenges. With preservation of these now submerged features under threat from commercial activities and natural erosion, bringing together existing knowledge through delivery of this work package is timely.

The Submerged Landscapes layer is delivered through the European Geological Data Infrastructure (EGDI) portal (www.emodnet-geology.eu). It is envisaged that the most recent update to the Submerged Landscapes layer (due April 2021) will be of practical use to the NEPTUNE INQUA project.

How to cite: Stewart, H.: Submerged Landscapes across European Seas: Harmonising information through the EMODnet-Geology project, EGU General Assembly 2021, online, 19–30 Apr 2021, EGU21-9217, https://doi.org/10.5194/egusphere-egu21-9217, 2021.