The Lefkada barrier and beachrock system (NW Greece) — Controls on coastal evolution and the significance of extreme wave events

May, Simon Matthias; Vött, Andreas; Brückner, Helmut; Grapmayer, Ralf; Handl, Mathias; Wennrich, Volker

doi:10.1016/j.geomorph.2011.10.038

Cited by 25 publications

(13 citation statements)

References 81 publications

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“…They attribute the formation of the identified washover fans to extreme waves of tsunamigenic origin. In a recent publication, May et al (2012) suggested that part of the coarse clastic sediment layers on the nearby Akarnanian coasts may be related to high energy storm waves instead of tsunami impacts. They also suggested that the extreme storm waves of the November 2007 event, as reported by Ghionis et al (2008), may be related to the dislocation and accumulation of beachrock fragments (up to ~40 cm length) along the Aghia Mavra barrier beach.…”

Section: Discussionmentioning

confidence: 99%

The Impact of an Extreme Storm Event on the Barrier Beach of the Lefkada Lagoon, NE Ionian Sea (Greece)

et al. 2015

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The present investigation examines the characteristics of a high energy storm event, that took place on November 9-11, 2007 in the NE Ionian Sea (eastern Mediterranean), and its impact upon the barrier beach that separates the Lefkada lagoon from the open Ionian Sea. The storm event was caused by NW winds with speeds exceeding 20 m/s (40 knots), which have an annual frequency of occurrence less than 0.015%. This high energy event produced waves with >5 m significant offshore height and 9.5 s period; these waves developed on 10 th November during the rapid rise of barometric pressure (~1.4 hPa/hr), which followed the barometric pressure drop from 1020.5 hPa at 06:00 (UTC) of 9 th November to 1001.7 hPa at 06:00 h (UTC) of 10 th November. Secondary breaking at the shoreline produced wave heights >1.5 m, associated with a surge of >0.4 m and a run-up capability of >2.4 m. The waves managed to overtop the barrier beach (elevations ~2.5 m), lowering the seaward side of the barrier beach by 10-30 cm and causing a coastline retreat of 0.9 to 2.2 m; these morphological changes correspond volumetrically to a sediment loss of approximately 8 m 3 /m of coastline length from the sub-aerial part of the beach. During the last three decades a significant change in the frequency of occurrence and direction (from S-SW-W to N-NW-NE) of severe storms with wind speeds exceeding 40 knots has been recorded, affecting the sediment transport pattern and contributing to the erosion of the north beaches of Lefkada.

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Section: Discussionmentioning

confidence: 99%

The Impact of an Extreme Storm Event on the Barrier Beach of the Lefkada Lagoon, NE Ionian Sea (Greece)

et al. 2015

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“…Event deposits stored in sedimentary archives along the coasts of Aktium Headland, including the Phoukias sand spit, were interpreted to be of tsunamigenic origin . Finally, May et al (2012) concluded that extreme wave events significantly influenced the coastal evolution in the Lefkada-Preveza area. A compilation of the previous findings is presented in Fig.…”

Section: Previous Findingsmentioning

confidence: 99%

“…1). Investigations on the washover structures in the eastern part of the Lefkada Lagoon were carried out by Vött et al (2008Vött et al ( , 2009a, and May et al (2012) (see also Fig. 2).…”

Section: Physical Settingmentioning

confidence: 99%

“…Most of the event deposits were interpreted to be of tsunamigenic origin. The main conclusions (dating of events, location, type of deposit) are depicted (modified from May et al, 2012).…”

Section: Physical Settingmentioning

confidence: 99%

“…Sand/shell debris layers intercalating the sedimentary sequence of sediment cores from the inner Lefkada Sound area were interpreted as tsunami deposits (Vött et al, 2009a). Washover structures in the eastern Lefkada Lagoon were dated to Classical-Hellenistic times (Vött et al, 2008) but may also be related to the 365 AD event May et al, 2012). High energy wave impact was also inferred in the Bay of Aghios Nikolaos due to several coarse clastic sediment layers which could be traced even in the western part of the Lake Voulkaria (Vött et al, 2008(Vött et al, , 2009b.…”

Section: Previous Findingsmentioning

confidence: 99%

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The Gyra washover fan in the Lefkada Lagoon, NW Greece—possible evidence of the 365 AD Crete earthquake and tsunami

et al. 2012

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Coastal geomorphological and geological archives store valuable information about the geodynamic evolution of coastal areas and the contributing geomorphodynamic processes. The coastal geomorphology of the LefkadaPreveza coastal zone, NW Greece, holds evidence for the influence of both gradual, low-energy and episodic, high-energy coastal processes. Situated close to the Hellenic Arc and the Cefalonia transform fault, the area belongs to one of the seismically most active regions in the Mediterranean. Thus, tsunami events are assumed to have contributed to the coastal evolution in the study area according to tsunami catalogues and field evidence from previous investigations. The northern part of the Lefkada Lagoon, separated from the Ionian Sea by an extensive barrier beach system, is characterized by a number of fan-like washover structures, formed by different washover generations. In this paper, we present detailed geomorphological, sedimentological, geochemical and foraminiferal investigations on the most prominent fan structure, the Gyra fan, based on terrestrial and lagoonal sediment cores. The Gyra fan consists of a coarse-grained sequence of fully marine origin on top of lagoonal mud and a palaeosol, respectively. The sequence shows numerous characteristics of extreme wave deposits. Due to the dimension and morphology of the fan, the existence of up to four consistent and correlative stratigraphic subunits, their landward thinning and their comparable sedimentary characteristics, we argue that a tsunami event induced the formation of the Gyra fan, comprising at least four major inundation impulses. According to radiocarbon dates, this geomorphological structure was most likely formed by teletsunami effects triggered by the 365 AD earthquake off western Crete.

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Tracing the Alkinoos Harbor of ancient Kerkyra, Greece, and reconstructing its paleotsunami history

et al. 2017

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In this study, the Alkinoos Harbor of ancient Corfu was investigated by means of geomorphological and sedimentological methods in order to reconstruct the ancient harbor's construction, its period of use and spatial extent, and local paleoenvironmental changes. We present sedimentological evidence for the Alkinoos Harbor that shows distinct signs of dredging activities. Although the harbor must have been in use from the Archaic period onwards, a set of paleoenvironmental proxies based on vibracoring, geophysical prospection, electrical conductivity logging, microfaunal studies, and geochemical analyses revealed typical sediments of a closed, protected Roman harbor that was in use between the 1st and 6th century A.D. In addition, sedimentological and microfaunal evidence allowed us to differentiate between different parts of the Roman harbor. In contrast, the pre-Roman harbor and its shipsheds were built on a sandy seashore. Our data revealed two distinct stratigraphic disruptions related to tsunamigenic impact. These paleotsunamis were

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The Lefkada barrier and beachrock system (NW Greece) — Controls on coastal evolution and the significance of extreme wave events

Cited by 25 publications

References 81 publications

The Impact of an Extreme Storm Event on the Barrier Beach of the Lefkada Lagoon, NE Ionian Sea (Greece)

The Impact of an Extreme Storm Event on the Barrier Beach of the Lefkada Lagoon, NE Ionian Sea (Greece)

The Gyra washover fan in the Lefkada Lagoon, NW Greece—possible evidence of the 365 AD Crete earthquake and tsunami

Tracing the Alkinoos Harbor of ancient Kerkyra, Greece, and reconstructing its paleotsunami history

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