Sea level changes in the Mediterranean

Questo documentario illustra i risultati di una ricerca multidisciplinare intrapresa per valutare come è cambiato il livello del Mar Mediterraneo dall’epoca romana ai giorni nostri, attraverso esplorazioni geologiche e archeologiche, l’utilizzo di dati strumentali e analisi geofisiche. I resti di antichi insediamenti marittimi lungo le coste del Mare Nostrum - come peschiere, porti e cave - sono i testimoni perenni dei grandi cambiamenti avvenuti sulla superficie della Terra. Questo viaggio nel tempo tra geologia, archeologia e geofisica permette di riconoscere e interpretare le cause del cambiamento. This movie shows the results of a multidisciplinary research undertaken to estimate how the Mediterranean Sea level has changed since the Roman age using geological and archaeological observations, instrumental data and geophysical analyses. Ancient remnants along the coastlines of the Mare Nostrum - such as fish tanks, harbours and quarries - are perpetual witnesses of the great changes experienced by the Earth’s crust surface. Using fascinating underwater views and animations, the movie takes the audience into a journey through time among geology, archaeology and geophysics, and explains why the changes occurred

Panarea bella e inquieta

L’isola di Panarea, con il suo piccolo arcipelago incastonato nel profondo blu del mare Tirreno, è uno dei luoghi più particolari e affascinanti del Mediterraneo. Non a caso è stata inclusa dall’Unesco tra quei siti che sono patrimonio dell’umanità. Il piccolo specchio di mare che la circonda è dominato dall’imponente isolotto di Basiluzzo, alto 165 metri, la cui cima è sormontata dai resti di una villa di epoca romana. Più piccoli, ma non meno particolari, sono gli isolotti di Bottaro, Lisca Bianca, Lisca Nera, i Panarelli e Dattilo. Ognuno con il proprio caratteristico profilo. Come Dattilo, dai colori forti e cangianti, che si staglia sul mare simile a una punta di lancia che fronteggia il cielo. Lo scenario è tra i più belli che si possano incontrare nel Mediterraneo. Da terra, Panarea si presenta come un’isola a forte vocazione turistica, frequentata dal jet set internazionale: hotel con vista mozzafiato sul mare e ville dalle terrazze esclusive sono diventati il simbolo di quest’isola e argomento di gossip per i migliaia di turisti «mordi e fuggi», che nel periodo estivo affollano l’arcipelago. Ma come è nata questa perla del Mediterraneo? Cosa sappiamo oggi di quest’isola vulcanica, probabilmente già nota ai greci per il suo termalismo

Lake Albano: bathymetry and level changes

Lake Albano is situated in the Colli Albani volcanic district, about 20 km SE of the city centre of Rome. It is 287 m above sea level and is the deepest of the volcanic crater lakes of Italy, presently being 167 m deep. It is 3.5 km long and 2.3 km wide with an area of about 6 km2. The crater has a long history, which starts with the formation of the Albano crater c. 70 ka BP, and shows evidence of human settlements since pre-historical times. Geological evidence indicates that a catastrophic overflow of the lake occurred in 398 BCE due to a rapid increase in the water level. This phenomenon persuaded the Romans to excavate an artificial outlet though the crater wall to control the lake level. The lake is thought to be a hazard for the surrounding human settlements and the city of Rome, so high-resolution multibeam bathymetry of Lake Albano was carried out for the Italian Dipartimento della Protezione Civile in order to evaluate the potential for CO2 storage and eruption from the lake. The shape of the crater floor was mapped in two and three dimensions. Here, we show the main submerged morphological features and a brief history of the changes in lake level, which still affect the basin today

The lake Albano: bathymetry and level changes

The Lake Albano is situated in the Colli Albani volcanic district, about 20 km SE from the city centre of Rome. It is 287 m above sea level and is the deepest among the volcanic crater lakes of Italy, being presently 167 m deep. It is 3.5 km long and 2.3 km wide with an area of about 6 km2. The crater has a long history, which starts with the formation of the Albano crater ~70 ka B.P., and shows evidence of human settlements since pre-historical times. Geological evidence indicates that a catastrophic overflow of the lake occurred in 396 B.C.E. due to a rapid increase of the water level. This phenomenon persuaded the Romans to excavate an artificial outlet though the crater wall to control the lake level. The lake is thought to be hazardous for the surroundings human settlements and the city of Rome, high resolution multibeam bathymetry of the of Lake Albano was performed for the Italian Dipartimento della Protezione Civile, in order to evaluate the potential for CO2 storage and eruption from the lake. The shape of the crater floor was mapped in 2-D and 3-D. Here, we show the main submerged morphological features and a brief history of the lake level changes, which still affect this basin today

Evidence of active subsidence at Basiluzzo island (Aeolian islands, southern Italy) inferred from a Roman age wharf

The Aeolian Arc (Southern Tyrrhenian Sea, Italy) is one of the most active volcanic areas of the Mediterranean basin, affected by volcanic/hydrothermal and seismic activity. Ancient populations settled this region since historical times, building coastal installations which currently are valuable archaeological indicators of relative sea level changes and vertical land movements. In this study we show and discuss data on the relative sea level change estimated from a submerged wharf of Roman age dated between 50 B.C. and 50 A.D., located at Basiluzzo Island. This structure has been studied through marine surveys and archaeological interpretations and is presently located at a corrected depth of 4.10 0.2 m. We explain this submergence by a cumulative effect of the relative sea level change caused by the regional glaciohydro- isostatic signal, active since the end of the last glacial maximum, and the local volcano-tectonic land subsidence. Finally, a total subsidence rate of 2.05 0.1 mm/yr 1, with a volcano-tectonic contribution of 1.43 0.1 mm/yr 1 for the last 2 ka BP, is inferred from the comparison against the latest predicted sea level curve for the Southern Tyrrhenian Sea, suggesting new evaluations of the volcanotectonic hazard for this area of the Aeolian islands

The first ultra-high resolution Digital Terrain Model of the shallow-water sector around Lipari Island (Aeolian Islands, Italy)

Very high resolution bathymetric map obtained through multibeam echosounders data are crucial to generate accurate Digital Terrain Models from which the morphological setting of active volcanic areas can be analyzed in detail. Here we show and discuss the main results from the first multibeam bathymetric survey performed in shallow-waters around the island of Lipari, the largest and the most densely populated of the Aeolian Islands (southern Italy). Data have been collected in the depth range of 0.1-150 m and complete the already existent high-resolution multibeam bathymetry realized between 100 and 1300 m water depth. The new ultrahigh resolution bathymetric maps at 0.1-0.5 m provide new insights on the shallow seafloor of Lipari, allowing to detail a large spectrum of volcanic, erosive-depositional and anthropic features. Moreover, the presented data allow outlining the recent morphological evolution of the shallow coastal sector of this active volcanic island, indicating the presence of potential geo-hazard factors in shallow waters

SEA LEVEL CHANGE ALONG THE TYRRHENIAN COAST FROM EARLY HOLOCENE TO THE PRESENT

In any discussion of the evolution of a river basin, the history of sealevel change is important since river gradients and delta developments are strongly influenced by local sea level. Also, sea level provides a reference for inferring past vertical tectonic stability from the geological record. Hence it is appropriate that the discussion on the Tiber basin starts with sea level change along the Tyrrhenian coast during the Holocene. The past evidence for sea level comes from inferences of the position of the sea surface with respect to the present. Hence it is a relative measure; a function of both the changing position of the ocean surface and of the land surface or an integrated measure of changes in ocean volume, land movement and redistribution of water within the ocean basins. The observation therefore contains information on all the processes that change these surfaces: on geophysical, glaciological and oceanographic processes

Current geodetic deformation of the Colli Albani volcano: a review

The quiescent Colli Albano volcano is presently characterised by moderate intensity earthquakes, seismic swarms, gas emissions and ongoing uplift that reflects the current evidences of its residual activity. An uplift of ~30 cm over the last 43 years was recently detected by levelling surveys performed in the time span 1950-1993 along a levelling line that crosses the highest elevation area of the western flank of the volcano. Space based GPS and Synthetic Aperture Radar Interferometry geodetic observations confirm that this uplift is distributed in a wide area around the craters of Albano and Nemi, where the most recent volcanic activity occurred. GPS data from continuous monitoring stations indicate that both horizontal and vertical deformations do occur and that can be addressed to a shallow magmatic source. All the geodetic observations are in agreement and highlight that the Colli Albani is still a potentially active volcano. Being located in a densely populated area close to Rome, the volcano should deserve the same monitoring and hazard assessment effort of any active volcano within urbanized areas. Here we review the geodetic results obtained during the last decades for the Colli Albani volcano

The dark side of the Albano crater lake

The Albano Lake is the deepest volcanic lake among the volcanoes located in the Italian peninsula. It belongs to the Colli Albani volcanic complex whose last largest eruptions are dated back to about ~30 Kyr, although minor events likely occurred during historical times at 7000 yr B.P. or earlier. After the end of the volcanic activity the Crater of Albano became a lake whose level changes are known since historical times. On November 2005, was performed the first very high resolution bathymetric survey of the Albano lake by means of a multibeam echo sounder, integrated with the GPS/RTK positioning technique A particular effort was devoted to produce a high resolution morphobathimetric map, which aims to provide a Digital Terrain Model of the lake floor for wide applications. The surveys did not revealed significant gas exhalative centres, which should indicate a current active gas release from the lake floor. Here we show the technical details of the bathymetric surveys, the very high resolution bathymetric map and the main morphological features of the Albano Lake bottom

Post glacial readjustment, sea level variations, subsidence and erosion along the Italian coasts

Ongoing sea level variations and vertical land movements measured by tide gauges and continuous GPS stations along the Italian coasts stem from several factors acting on different spatiotemporal scales. Conversely to tectonics and anthropogenic effects, which are characterized by a heterogeneous signal, the adjustment of solid Earth and geoid to the melting of the late– Pleistocene ice sheets results in a smooth long–wavelength pattern of sea level variation and vertical deformation across the Mediterranean, mostly driven by the melt water load added to the basin. In this work we define upper and lower bounds of the effects of glacial isostatic adjustment (GIA) on current sea level variations and vertical ground movements along the coasts of Italy. For plausible mantle viscosity profiles we explore to what extent the spatial variability of observed rates may be attributed to delayed isostatic recovery of both solid Earth and geoid. In addition, we show that long–wavelength patterns of sea level change are tuned by the effects of GIA, and that coastal retreat in Italy is broadly correlated with the expected ongoing rates of post–glacial sea level variations