Scardino, Giovanni

Late Quaternary crustal uplift is well recognized in northeast Sicily, southern Italy, a region also prone to damaging earthquakes such as the 1908 “Messina” earthquake (Mw 7.1), the deadliest seismic event reported within the Italian Earthquake Catalogue. Yet it is still understudied if, within the Milazzo Peninsula, crustal uplift rates are varying spatially and temporally and whether they may be either influenced by (i) local upper-plate faulting activity or (ii) deep geodynamic processes. To investigate the long-term crustal vertical movements in northeast Sicily, we have mapped a flight of Middle-Late Pleistocene marine terraces within the Milazzo Peninsula and in its southern area and refined their chronology, using a synchronous correlation approach driven by published age controls. This has allowed a new calculation of the associated crustal uplift rates, along a north–south oriented coastal-parallel transect within the investigated area. Our results show a decreasing uplift rate from south to north across the Milazzo Peninsula and beyond, and that the associated rates of uplift have been constant through the Late Quaternary. This spatially varying yet temporally constant vertical deformation helps to constrain the amount of uplift, allowing us to explore which is the driving mechanism(s), proposing a few related scenarios. We discuss our results in terms of tectonic implications and emphasize the importance of using appropriate approaches, as such applying a synchronous correlation method, to refine chronologies of undated palaeoshorelines when used for tectonic investigations.

We investigated the Late Pleistocene-Holocene crustal vertical movements off the coast of Marzamemi village in SE Sicily, Italy. By using a Synchronous Correlation Approach (SCA), we analysed terraced landforms that characterize a submerged sector within one of Southern Italy's most seismically active regions. In this area, the emerging portion of the NE-SW oriented bulge of the African foreland structurally shapes the coastal and marine regions off Marzamemi village. Based on a newly created 17 km2 high-resolution bathymetric map generated from a Multibeam Echosounder (MBES) survey conducted in June 2021, we identified and examined four main paleo-shorelines identifying four submerged terraces. Terraced landforms play a crucial role in reconstructing Quaternary glacial and interglacial stages, offering insights into associated sea level fluctuations. Through the application of the SCA, our goal is to refine the chronology of these recently mapped and submerged marine terraces off the Marzamemi village, thereby contributing to the calculation of associated rates of crustal vertical movements. We demonstrate that these rates persist constantly throughout the Late Pleistocene-Holocene epoch, suggesting overall tectonic stability, with a slight and likely local fault-related subsidence. We explore a few chronology scenarios, raising questions about whether these submerged marine terraces are indeed recording the Late Pleistocene-Holocene limit or not. This research contributes to a better understanding of the geological dynamics in this region and sheds light on the potential factors influencing coastal landscape development over time.

Extreme atmospheric-marine events, known as medicanes (short for "Mediterranean hurricanes"), have affected the Mediterranean basin in recent years, resulting in extensive coastal flooding and storm surges, and have occasionally been responsible for several casualties. Considering that the development mechanism of these events is similar to tropical cyclones, it is plausible that these phenomena are strongly affected by sea surface temperatures (SSTs) during their development period (winter and autumn seasons). In this study, we compared satellite data and the numerical reanalysis of SSTs from 1969 to 2023 with in situ data from dataloggers installed at different depths off the coast of southeastern Sicily as well as from data available on Argo floats on the Mediterranean basin. A spectral analysis was performed using a continuous wavelet transform (CWT) for each SST time series to highlight the changes in SSTs prior to the occurrence of Mediterranean Hurricanes as well as the energy content of the various frequencies of the SST signal. The results revealed that decreases in SST occurred prior to the formation of each Mediterranean hurricane, and that this thermal drop phenomenon was not observed in intense extra-tropical systems. The spectral analyses revealed that high CWT coefficients representing high SST energy contents were observed before the occurrence of a Mediterranean hurricane. This information may provide a useful fingerprint for distinguishing Mediterranean hurricanes from common seasonal storms at the onset of these events.

Microseism, the most continuous seismic signal on the Earth generated by the interaction between the hydrosphere, the atmosphere, and the solid Earth, is a useful tool for acquiring information about climate change. Indeed, several authors dealt with the relationship microseism-sea state and microseism-cyclonic activity, considering in particular tropical cyclones, hurricanes, typhoons, and recently Medicanes (small-scale tropical cyclones that occur in the Mediterranean Sea). In this study, we analyze, from a seismic point of view, several meteorological events that occurred in the Mediterranean Sea during the period November 2011 - February 2023. In particular, we consider 9 Medicanes and 4 more common storms. Despite the marked differences between them, each of these events caused heavy rainfall, strong wind gusts, violent storm surges with significant wave heights usually greater than 3 meters, and damage along the exposed coast. Occasionally, these events caused deaths and injuries. In this work, we analyzed the seismic signal recorded by 104 seismic stations, installed along the Italian, Maltese, Greek, and France coastal areas, and 15 seismic stations, installed in the Etnean area used only to perform array analysis. We deal with the relationships between the considered meteorological events and the features of microseism in terms of spectral content, space-time variation of the amplitude, and source locations tracked using two different methods (a grid search approach based on seismic amplitude decay and array techniques). By comparing the positions of the microseism sources, obtained from our analysis, with the areas of significant storm surges, retrieved from hindcast data, we observe that the microseism locations are in agreement with the actual locations of the storm surges for 10 out of 12 events analyzed (two Medicanes present very low intensity in terms of meteorological parameters and the microseism amplitude does not show significant variations during these two events). In addition, we also carried out two analyses that allowed us to obtain both the seismic signature of these events, by using a method that exploits the coherence of continuous seismic noise, and their strength from a seismic point of view, called Microseism Reduced Amplitude. By integrating the results obtained from these two methods, we can "seismically" distinguish Medicanes and common storms. Consequently, we demonstrate the possibility of creating a novel monitoring system for Mediterranean meteorological events by incorporating microseism information alongside with other techniques (e.g. wave buoy, wave gauge, and High-Frequency coastal radar) commonly used for studying and monitoring meteorological phenomena. In addition, since the seismometers were among the first geophysical instruments installed, it is possible to digitize old seismograms and examine historical data shedding new light on extreme weather events in a climate change scenario.

In this work, we analyze 12 meteorological events that occurred in the Mediterranean Sea during the period November 2011-November 2021 from a seismic point of view. In particular, we consider 8 Medicanes and 4 more common storms. Each of these events, in spite of the marked differences between them, caused heavy rainfall, strong wind gusts and violent storm surge with significant wave heights usually >3 m. We deal with the relationships between these meteorological events and the features of microseism (the most continuous and widespread seismic signal on Earth) in terms of spectral content, space-time variation of the amplitude and source locations tracked employing two different methods (amplitude decay-based grid search and array techniques). By comparing the positions of the microseism sources with the areas of significant storm surges, we observe that the microseism locations align with the actual locations of the storm surges for 10 out of 12 events analyzed (two Medicanes present very low intensity in terms of meteorological parameters and the microseism amplitude does not show significant variations during these two events). We also perform two analyses that allowed us to obtain both the seismic signature of these events, by using a method that exploits the coherence of continuous seismic noise, and their strength from a seismic point of view, called Microseism Reduced Amplitude. In addition, by integrating the results obtained from these two methods, we are able to "seismically" distinguish Medicanes and common storms. Consequently, we demonstrate the possibility of creating a novel monitoring system for Mediterranean meteorological events by incorporating microseism information alongside with other commonly employed techniques for studying meteorological phenomena. The integration of microseism with the data provided by routinely used techniques in sea state monitoring (e.g., wave buoy and HF radar) has the potential to offer valuable insights into the examination of historical extreme weather events within the context of climate change.

To refine knowledge about terrace phases and uplift history for a tectonically poor deformed region, we apply the synchronous correlation method to reconstruct the chronology of a poorly constrained sequence of raised palaeoshorelines on the Apulian foreland, southern Italy. This work uses new chronological constraints obtained by amino acid racemisation (AAR) and isoleucine/alloisoleucine epimerisation (IE) on Patella spp., Thetystrombus latus (Gmelin), Glycymeris sp., and ostracods and U-series dating on corals Hoplangia durotrix Gosse and Cladocora caespitosa Linneo. This procedure provides a quantitative estimate of the vertical movements and associated rates within a region of the Apulian foreland. The synchronous correlation method uses sea-level highstands and uplift rate(s) as inputs; in particular, for sea-level highstands, the inputs are the age of the highstands and the sea-level elevation of the highstands relative to the present-day sea level. The output is a set of currently expected elevations of each sea-level highstand (the present elevations of palaeoshorelines). We then used regression analysis to assess the robustness between our observed palaeoshorelines and expected elevations of sea-level highstands. Our results show that the best fitting scenario is obtained using the sea-level curves of (i) Waelbroeck et al. (2002) from present to 410 ky BP and (ii) Rohling et al. (2014) from 410 to 590 ky BP as inputs for our synchronous correlation method, with uplift rates ranging from 0.09 mm/y to 0.07 mm/y with a mean value of 0.08 mm/y from 590 ky BP onwards. We recognised palaeoshorelines in the field belonging to the following highstands: 120 ky BP (MIS 5.5, second peak), 127 ky BP (MIS 5.5, first peak), 212 ky BP (MIS 7.3), 330 ky BP (MIS 9.3), 410 (MIS 11), 525 ky BP (MIS 13.3), and 590 ky BP (MIS 15). Our results show field observations of the reoccupation effect of younger palaeoshorelines over older ones due to the relatively slow uplift rates measured in the investigated area as predicted by our synchronous correlation method. In particular, we show a well-mapped and described reoccupation of the MIS 5.5 palaeoshoreline over the MIS 7.3 palaeoshoreline, constrained by new absolute dating. In addition, the data from the Apulian foreland suggest an MIS 7.3 highstand close to the present sea level.

The disastrous earthquake of 1693 AD caused over 60,000 causalities and the total destruction of several villages and towns in south-eastern Sicily. Immediately after the earthquake, a tsunami struck the Ionian coasts of Sicily and the Messina Strait and was probably recorded even in the Aeolian Islands and Malta. Over the last few decades, the event has been much debated regarding the location of the seismogenic source and the possible cause of the associated tsunami. The marine event has been related to both a submarine landslide and a coseismic displacement at the seafloor. To better define the most reliable sources and dynamics of the tsunami, we couple high-resolution marine seismic survey data with hydrodynamic modelling to simulate various scenarios of tsunami generation and propagation. Results from the simulations are compared with geomorphological evidence of past tsunami impacts, described in previous work along the coast of south-eastern Sicily, and within historical chronicles and reports. The most reliable scenario considers the 1693 event composed by two different tsunami waves: a first wave generated by the coseismic fault displacement at the seafloor and a second wave generated by a submarine landslide, triggered by the earthquake shaking. Tsunami modelling shows that a simultaneous movement between fault displacement and submarine mass movement could determine a destructive interference on the tsunami waves, resulting in a reduction in wave height. For this reason, the second tsunami wave probably occurred with a maximum delay of few minutes after the one generated by the earthquake and induced a greater flooding. The double-source model could explain the observation because in the course of other destructive earthquakes in south-eastern Sicily, such as that of 1169 AD, the associated tsunami caused less damages. This implies the need to better map, define and assess the hazard responsible for this type of tsunami events.

Low-lying coastal zones are highly subject to coastal hazards as a result of sea-level rise enhanced by natural or anthropogenic land subsidence. A combined analysis using sea-level data and remote sensing techniques allows the estimation of the current rates of land subsidence and shoreline retreat, supporting the development of quantified relative sea-level projections and flood maps, which are appropriate for specific areas. This study focuses on the coastal plain of Tavoliere delle Puglie (Apulia, Southern Italy), facing the Adriatic Sea. In this area, land subsidence is mainly caused by long-term tectonic movements and sediment compaction driven by high anthropogenic pressure, such as groundwater exploitation and constructions of buildings. To assess the expected effects of relative sea-level rise for the next decades, we considered the following multidisciplinary source data: (i) sea-level-rise projections for different climatic scenarios, as reported in the Sixth Assessment Report of the Intergovernmental Panel on Climate Change, (ii) coastal topography from airborne and terrestrial LiDAR data, (iii) Vertical Land Movement (VLM) from the analysis of InSAR and GNSS data, and (iv) shoreline changes obtained from the analysis of orthophotos, historic maps, and satellite images. To assess the expected evolution of the coastal belt, the topographic data were corrected for VLM values, assuming that the rates of land subsidence will remain constant up to 2150. The sea-level-rise projections and expected flooded areas were estimated for the Shared Socioeconomic Pathways SSP1-2.6 and SSP5-8.5, corresponding to low and high greenhouse-gas concentrations, respectively. From our analysis, we estimate that in 2050, 2100, and 2150, up to 50.5 km2, 118.7 km2 and 147.7 km2 of the coast could be submerged, respectively, while beaches could retreat at rates of up to 5.8 m/yr. In this area, sea-level rise will be accelerated by natural and anthropogenic land subsidence at rates of up to −7.5 ± 1.7 mm/yr. Local infrastructure and residential areas are thus highly exposed to an increasing risk of severe inundation by storm surges and sea-level rise in the next decades.

The global sea-level rise (SLR) projections for the next few decades are the basis for developing flooding maps that depict the expected hazard scenarios. However, the spatially variable land subsidence has generally not been considered in the current projections. In this study, we use geodetic data from global navigation satellite system (GNSS), synthetic aperture radar interferometric measurements (InSAR) and sea-level data from tidal stations to show the combined effects of land subsidence and SLR along the coast between Catania and Marzamemi, in south-eastern Sicily (southern Italy). This is one of the most active tectonic areas of the Mediterranean basin, which drives accelerated SLR, continuous coastal retreat and increasing effects of flooding and storms surges. We focus on six selected areas, which show valuable coastal infrastructures and natural reserves where the expected SLR in the next few years could be a potential cause of significant land flooding and morphological changes of the coastal strip. Through a multidisciplinary study, the multi-temporal flooding scenarios until 2100, have been estimated. Results are based on the spatially variable rates of vertical land movements (VLM), the topographic features of the area provided by airborne Light Detection And Ranging (LiDAR) data and the Intergovernmental Panel on Climate Change (IPCC) projections of SLR in the Representative Concentration Pathways RCP 2.6 and RCP 8.5 emission scenarios. In addition, from the analysis of the time series of optical satellite images, a coastal retreat up to 70 m has been observed at the Ciane river mouth (Siracusa) in the time span 2001–2019. Our results show a diffuse land subsidence locally exceeding 10 ± 2.5 mm/year in some areas, due to compacting artificial landfill, salt marshes and Holocene soft deposits. Given ongoing land subsidence, a high end of RSLR in the RCP 8.5 at 0.52 ± 0.05 m and 1.52 ± 0.13 m is expected for 2050 AD and 2100 AD, respectively, with an exposed area of about 9.7 km2 that will be vulnerable to inundation in the next 80 years.

The coastal vulnerability along the Mediterranean coasts is increasing, especially in response to the occurrence of tropical-like cyclones, known as Medicanes, which have become more intense than in the past. A peculiar case was the impact of Medicane Zorbas in September 2018 along the coasts of south-eastern Sicily, where it caused inland flooding and damages to the socio-economic activities. Here, Zorbas effects are reconstructed through post-event geomorphological surveys, interviews with direct witness and analyses of video recorded by surveillance systems or found in social media. These data allowed us 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 produced by the main seasonal storms affecting the areas from 2015 to 2019; nevertheless, it is comparable with the flooding generated by Medicane Qendresa that impacted south-eastern Sicily in 2014. Wave propagation and extreme water level modelling, performed for the main storm events that occurred in the area since 2005, and analyses of data recorded by tide gauges of Catania, Porto Palo di Capo Passero and Malta since 2008, showed that Medicanes generate greater flooding than seasonal storms because they can induce higher and longer surge along the coastline. Collected data indicated that the 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 south-eastern 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 will probably be characterized by longer duration and greater intensity than at the present.