Geoenvironmental Institute

Marousi, Greece

Geoenvironmental Institute

Marousi, Greece
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Evelpidou N.,National and Kapodistrian University of Athens | Kampolis I.,National and Kapodistrian University of Athens | Pirazzoli P.A.,Laboratoire Of Geographie Physique | Vassilopoulos A.,Geoenvironmental Institute
Global and Planetary Change | Year: 2012

The recent rise in global sea level is causing the disappearance of an important geomorphological sea-level indicator, the tidal notch.Tidal notches have often been used in carbonate coasts for Quaternary and late Holocene sea-level reconstructions and estimation of tectonic movements, especially in uplifting areas. In this paper, we review the rates of tidal notch development, and examine the recent gradual depletion of this feature, during at least the last century, and its relation to the increasing rates of sea-level rise. Some examples of tidal notch development are provided with fossil submerged notches from Greece. Although tidal notches are no longer forming in the present-day mid-littoral zone, underwater marks on carbonate cliffs may still provide evidence of submerged tidal notches corresponding to former sea-level positions, or of recent vertical shoreline displacements of seismic origin. © 2012 Elsevier B.V.


Evelpidou N.,National and Kapodistrian University of Athens | Pirazzoli P.A.,French National Center for Scientific Research | Saliege J.-F.,French National Center for Scientific Research | Vassilopoulos A.,GeoEnvironmental Institute
Continental Shelf Research | Year: 2011

The possibility of Holocene subsidence along the northern coast of the Corinth Gulf is often mentioned in the literature; however, systematic detailed evidence that submergence (e.g. of archaeological remains) does not simply depend from eustatic sea-level rise is most often missing. In this paper, a new detailed study of submerged tidal-notch profiles along the limestone coast has shown that periods of sea-level stability are intercalated with periods of rapid subsidence or gradual relative sea-level rise. It appears that most of the sites considered, seem to have been affected by a relatively recent co-seismic subsidence of about half a meter, whereas during the longer period, by stages of relative sea-level stability and/or gradual relative sea-level rise. This evidence of subsidence is confirmed by radiocarbon dating in doline sediments, suggesting that during certain periods, a relative sea-level rise was much faster than the raising suggested by glacio-eustatic or hydro-isostatic estimations. Juxtaposing a list of known earthquakes occurred in the area shows that several earthquakes (e.g. the 1981 one for the easternmost sites considered) are potential candidates for the recent co-seismic displacements and thus supporting the geomorphological interpretations. © 2011 Elsevier Ltd.


Evelpidou N.,National and Kapodistrian University of Athens | Vassilopoulos A.,GeoEnvironmental Institute | Pirazzoli P.A.,French National Center for Scientific Research
Geomorphology | Year: 2012

Detailed mapping along the coasts of Skyros Island (Aegean Sea) provided new evidence concerning the rates and the modality of subsidence in the area. The results are provided through the study of the shape and the dimensions of the two submerged notches detected around the carbonate coasts of the island.It is apparent that the island has been submerged not only due to the global sea-level rise during the last two centuries (1.8 ± 0.3. mm/year between 1950 and 2000), but also because of tectonic events testified by the type of the submerged notches. Some of these tectonic events seem to be of gradual and some of co-seismic origin. The transition of MSL from the retreat point of the lower notch to the retreat point of the upper notch seems to have been produced by co-seismic subsidence of about 55. cm at slightly less than 850. years BP. © 2011 Elsevier B.V..


Evelpidou N.,National and Kapodistrian University of Athens | Vassilopoulos A.,Geoenvironmental Institute | Pirazzoli P.A.,Laboratoire Of Geographie Physique
Marine Geology | Year: 2012

Detailed mapping along the northwestern coastline of Euboea has provided new evidence of colonization by Lithophaga lithophaga (L.) reaching about 3.8. m above the present biological MSL. Such marine biological marks, together with morphological notches, correspond to the occurrence of two sequences of Holocene vertical displacements higher than those reported by previous studies, on the central part of the southern coast and along the northern coast of the island. A well developed emerged notch is found at + 1.7 ± 0.1. m above present mean sea level, whereas the uppermost part of the lithophagid holes suggest a former emerged shoreline at least at + 3.8 ± 0.1. m. Radiocarbon AMS dating of Lithophaga shells found in their burrows, showed that the lower uplifted shoreline corresponds to a tectonic event (probably coseismic) apparently dated at 2200 a BP, while the higher shoreline corresponds to an older relative sea-level transgression, possibly of tectonic origin, apparently dated about 5570 a BP. The apparent radiocarbon age of lithophagid shells can be about 350 to 400. years older than the uplift event that exposed them, due to incorporation of host-rock carbon. Nevertheless, the two new paleoshorelines provide evidence that repeated uplift movements, greater than those reported by previous authors, occurred during the late Holocene, uplifting the western part of the island. © 2011 Elsevier B.V.


Evelpidou N.,National and Kapodistrian University of Athens | Pirazzoli P.A.,Laboratoire Of Geographie Physique | Vassilopoulos A.,Geoenvironmental Institute | Tomasin A.,University of Venice | Tomasin A.,CNR Marine Science Institute
Zeitschrift fur Geomorphologie | Year: 2011

Detailed mapping of coastline around Theologos area revealed the existence of well developed permanently submerged notches 75 ± 10 cm below present mean sea level. The regional occurrence of well preserved submerged tidal notches suggests their coseismic origin. The submergence of this Holocene shoreline possibly occurred at 1894 AD. Average submergence rate of 6.08 mm/yr may be estimated by a well preserved recumbent U-shaped notch. The retreating point depth suggests that the developing period of the notch might have been of the order of as much as three thousand years. Several non in situ large rock blocks, containing marine fossils (Lithophaga, Vermetids, Serpulids) in growth position, seem to have been projected on the coast by a tsunami wave, which might have been caused by the same coseismic episode. © 2011 Gebr. Borntraeger Verlagsbuchhandlung, Stuttgart, Germany.


Evelpidou N.,National and Kapodistrian University of Athens | Melini D.,INGV | Pirazzoli P.A.,French National Center for Scientific Research | Vassilopoulos A.,GeoEnvironmental Institute
International Journal of Earth Sciences | Year: 2014

An underwater geomorphological survey along the coasts of six Cycladic islands (Sifnos, Antiparos, Paros, Naxos, Iraklia and Keros) revealed widespread evidence of seven submerged tidal notches. At least seven former shorelines were identified at depths between 280 ± 20 and 30 ± 5 cm below modern sea level. The vertical succession of several submerged notches suggests the occurrence of rapid subsidence events, potentially of seismic origin. Comparison with other sea-level indicators from Naxos and Delos islands indicates that these relative sea-level changes took place after 3300 BP and provides a rough estimate of the time of development of several submerged shorelines. The submergence of the uppermost notch at -30 ± 5 cm is ascribed to effects of the recent global sea-level rise occurred during the last two centuries and, at least in part, to effects of recent earthquakes. Potential effects of the 1956 Amorgos earthquake with regard to coseismic and post-seismic vertical displacement have been recently investigated using a modellistic approach. According to the above, the lower shorelines should result from repetitive subsidence events and not from gradual subsidence. © 2013 Springer-Verlag Berlin Heidelberg.


Evelpidou N.,National and Kapodistrian University of Athens | Melini D.,Italian National Institute of Geophysics and Volcanology | Pirazzoli P.,French National Center for Scientific Research | Vassilopoulos A.,Geoenvironmental Institute
Continental Shelf Research | Year: 2012

An underwater geomorphological survey along the coasts of six Cycladic islands (Sifnos, Antiparos, Paros, Naxos, Iraklia and Keros) revealed widespread evidence of a recent 30-40. cm submergence, part of which may have seismic origin. Comparison with information reported from earthquakes having affected the area suggests that at least part of the recent submergence might be an effect of the 1956 Amorgos earthquake. Modelling of the co-seismic and short-term post-seismic effects of the earthquake revealed that part of the observed subsidence may be explained in some of the islands by a fast post-seismic relaxation of a low-viscosity layer underlying the seismogenic zone. However far-field observations are underestimated by our model, and may be affected by a wider deformation field induced by the largest aftershock of the Amorgos sequence, or by other earthquakes. © 2012 Elsevier Ltd.


Evelpidou N.,National and Kapodistrian University of Athens | Pirazzoli P.,French National Center for Scientific Research | Vassilopoulos A.,Geoenvironmental Institute | Spada G.,Urbino University | And 2 more authors.
Geoarchaeology | Year: 2012

We present estimates for late Holocene relative sea level change along the Tyrrhenian coast of Italy based on morphological characteristics of eight submerged Roman fish tanks (piscinae) constructed between the 1st century B.C. and the 2nd century A.D. Underwater geomorphological features and archaeological remains related to past sea level have been measured and corrected using recorded tidal values. We conclude that local sea level during the Roman period did not exceed 58 ± 5 cm below the present sea level. These results broadly agree with previous observations in the region but contrast with recent analysis that suggests a significantly larger sea level rise during the last 2000 years. Using a glacial isostatic adjustment model, we explain how regional sea level change departs from the eustatic component. Our calculation of relative sea level during the Roman period provides a reference for isolating the long-wavelength contribution to sea level change from secular sea level rise. Precise determination of sea level rise in the study area improves our understanding of secular, instrumentally observed, variations across the Mediterranean. © 2012 Wiley Periodicals, Inc.

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