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

May, Simon Matthias; Vött, Andreas; Brückner, Helmut; Smedile, Alessandra

doi:10.5047/eps.2012.03.007

Cited by 28 publications

(13 citation statements)

References 73 publications

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“…Lagoons, small lakes and saltpans: Lefkas lagoon (L03) is the largest lagoon of the Ionian Islands (Figure 5d,e), separated from the Ionian Sea by the narrow sandy Gyra spit (L02), which is a large sandy barrier landform in the northernmost part of Lefkas (Figure 6a,b), ranging from the area of Gyra to Aghios Ioannis (Figures 2 and 4). The sediment of the sand strip comes mainly from landslides due to earthquakes on the west coast of the island [90,91] (May et al, 2012a,b), while white and coarse beachrocks can be found at the mean sea-level, along the strip's coastline ( [91] and own observations). Moreover, palaeo-tsunami deposits have been located, probably associated with the 365 A.D. earthquake in Crete [91][92][93].…”

Section: Lefkas Islandmentioning

confidence: 99%

Assessment of Geological Heritage Sites and Their Significance for Geotouristic Exploitation: The Case of Lefkas, Meganisi, Kefalonia and Ithaki Islands, Ionian Sea, Greece

et al. 2022

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Geological heritage or geoheritage refers to the total of geosites, i.e., areas of high geological interest in a given area. Geosites have a high potential of attracting geotourists, thus contributing to the development of the local economy. Assessing sites of geological interest can contribute to their promotion, as well as their preservation and protection. Greece’s geotectonic position in the convergent zone between the African and Eurasian plates has contributed to the existence of a considerable wealth of geosites, with the particularly active geotectonic region of the Ionian Sea characterized as a geoheritage hotspot. The purpose of this study is the selection of several such sites from the islands of Lefkas, Meganisi, Kefalonia and Ithaki and their assessment regarding their scientific, environmental, cultural, economic and aesthetic value. The most representative sites for the individual disciplines of geology (e.g., geomorphology, tectonics, stratigraphy and palaeontology) have been chosen, mapped and assessed, while indicative georoutes are proposed, which could aid the island’s geotouristic promotion to geologist and non-geologist future visitors.

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Section: Lefkas Islandmentioning

confidence: 99%

Assessment of Geological Heritage Sites and Their Significance for Geotouristic Exploitation: The Case of Lefkas, Meganisi, Kefalonia and Ithaki Islands, Ionian Sea, Greece

et al. 2022

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“…Thus, the region is characterized by a high seismic and tsunami hazard risk (Papazachos & Dimitriu, ). In fact, numerous historical accounts (Soloviev et al ., ), as well as detailed sedimentary studies indicate repeated tsunami landfall in western Greece (Scheffers et al ., ; Vött et al ., ; May et al ., ). However, Marriner et al .…”

Section: Study Areamentioning

confidence: 76%

“…Thus, the region is characterized by a high seismic and tsunami hazard risk (Papazachos & Dimitriu, 1991). In fact, numerous historical accounts (Soloviev et al, 2000), as well as detailed sedimentary studies indicate repeated tsunami landfall in western Greece (Scheffers et al, 2008;V€ ott et al, 2010;May et al, 2012). However, Marriner et al (2017), using statistical analysis, suggested that repeated cycles of strong storms could be an alternative cause for boulder movement.…”

Section: Western Greecementioning

confidence: 99%

Monitoring the sedimentary budget and dislocated boulders in western Greece – results since 2008

2020

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Dislocated boulders are one sign of high‐energy wave impacts on coasts. These high‐energy impacts, caused by severe storms or tsunamis, can trigger initial cracking and transport of boulders. Monitoring of these boulders, as well as the associated coastal sites is important in distinguishing between gradual coastal processes and high‐energy events. Western Greece is a seismically active area, where tsunamis and high‐energetic storms might occur and such past events are documented by historic and geoscientific research, making it an ideal location for monitoring dislocated boulders. Since 2008, monitoring of eight different coastal sites in this region was conducted by terrestrial laser scanning and photogrammetric approaches, with low‐cost unmanned aerial vehicles. The re‐use of similar surveying points in following years, allowed highly accurate monitoring. Point clouds derived from these methods were evaluated for change detection by point cloud comparisons. The data were also used to establish accurate three‐dimensional models of dislocated boulders (n = 70). The determined boulder volumes of these accurate three‐dimensional models were incorporated in wave transport equations and wave decay curves, and compared with monitoring results. A comprehensive overview of dislocated boulders in western Greece is presented. Three‐dimensional boulder reconstruction is compared to an approach which uses a tape‐based measuring of boulder axes, with the tape‐based measurement showing a mean overestimation of mass by 32%. Accurate monitoring over time by both methods, is achieved by using fixed networks of reference points. Changes for each site over time, detected by direct point cloud comparisons, are fit to the possible inundation calculated by wave decay curves based on computed minimum wave heights for boulder transport. Both storm and tsunami waves may have initiated movement from the cliff edge and further transport is also possible. However, boulders showed no further movement from their current position in the area for the time period of this study.

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“…The associated tsunami devastated coasts and man-made coastal infrastructure between the Levante and Italy as documented by geological evidence (e.g. De Martini et al 2010, Gerardi et al 2012, Smedile et al 2011, 2012, May et al 2012, Ntageretzis et al 2015, Polonia et al 2013, Finkler et al 2018. Impacted regions are located up to 500-600 km distant from the suggested tsunamigenic fault.…”

Section: Synthesis Of Archaeological and Geoarchaeological Datamentioning

confidence: 99%

Geoarchaeological evidence of Ostia’s river harbour operating until the fourth century AD

Vött

Willershäuser

Hadler

et al. 2020

Archaeol Anthropol Sci

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Ancient Ostia at the mouth of the River Tiber into the Tyrrhenian Sea was largely significant for the economic supply of Rome. Ostia itself experienced an extraordinary period of prosperity in the second century AD. Starting in AD 42, a first new harbour at Portus was built by Emperor Claudius close to Ostia. It reached its full functionality under Emperor Trajan in the early second century AD, only. At Ostia itself, previous archaeological and geoarchaeological studies have brought to light a lagoon-type harbour at the western fringe of the city operating between the fourth and the second century BC in an artificially excavated harbour basin. From the second century BC onwards, a considerably smaller and shallower part of this western harbour basin was still in function as a fluvial harbour. So far, it was unclear whether Ostia's western harbour was still in use when the harbour at Portus was set into function in the first to second century AD, or if the latter partially replaced Ostia's harbour infrastructure. According to archaeological evidence, Ostia's navalia-temple-complex, the main building at the eastern fringe of the western river harbour basin, was built in the second quarter of the first century AD. Was this prestigious harbour building erected although the associated harbour seemed to have been already given up before? We conducted detailed geoarchaeological investigations at the immediate western front of the navalia-temple complex. Results were compared with archaeological data obtained from excavations carried out in 2000/2001. A multi-proxy approach was used to reconstruct the history and evolution of the harbour. It was possible to identify subsurface structures and evaluate the local stratigraphy. Vibracoring brought to light a more than 1 m thick section of an opus reticulatum wall with parts of the original opus latericium on top. Such walls originally separated vaulted shipshed chambers of the navalia-temple complex at Ostia, which in turn formed the substructure of a temple complex located above it. Another core revealed the sedimentary infill of a former chamber of the building. Based on radiocarbon dating, the navalia was in use between the first and the fourth centuries AD with a water depth of maximum ca. 1.2 m at the immediate western front. This is in agreement with the date of construction of the navalia-temple complex in the second quarter of the first century AD. The relative sea level at that time was around 0.64 m below the present sea level. The harbour and the navalia were obviously accessible only for flat-keeled lighters and cargo boats. Larger cargo ships were either unloaded along the riverbank to the north of ancient Ostia or moored offshore, their freight being reloaded to smaller lighters. Chronostratigraphic data further show that the navalia-temple complex was in use until the second half of the fourth century AD. It was not before AD 355-363 or shortly afterwards, that the harbour site was abandoned. Ostia's western river harbour was neither abandoned nor completely ...

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

Cited by 28 publications

References 73 publications

Assessment of Geological Heritage Sites and Their Significance for Geotouristic Exploitation: The Case of Lefkas, Meganisi, Kefalonia and Ithaki Islands, Ionian Sea, Greece

Assessment of Geological Heritage Sites and Their Significance for Geotouristic Exploitation: The Case of Lefkas, Meganisi, Kefalonia and Ithaki Islands, Ionian Sea, Greece

Monitoring the sedimentary budget and dislocated boulders in western Greece – results since 2008

Geoarchaeological evidence of Ostia’s river harbour operating until the fourth century AD

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