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Geophysical and geoarchaeological investigations were carried out in the Wadden Sea of North Frisia (Schleswig-Holstein, Germany) to elucidate major environmental changes that considerably altered the coastal landscape since medieval times. Between the 12 th and 14 th cent. AD, the present-day tidal flats around the marsh island Hallig Sudfall belonged to the historical Edomsharde district and its main settlement Rungholt . For North Frisia, it is well known that during medieval and early modern times, extreme storm surges caused major land losses associated with a massive landward shift of the coastline. Today, cultural traces like remains of dikes, drainage ditches, terps or even plough marks are still visible in the Wadden Sea and provide evidence of the once cultivated marshland. Based on a multi-proxy analysis of sediment cores retrieved from the tidal flat zone around Hallig Sudfall and from the Hallig itself, we identified a late medieval paleosol associated with the formerly cultivated marshland most probably belonging to the Edomsharde and local trade centre of Rungholt. Around Hallig Sudfall, remains of medieval marsh deposits were found partly eroded and covered by a coarse-grained high-energy deposit including abundant shell debris and artefacts. Based on sedimentological, micropaleontological, geochemical and geochronological data, we conclude that these deposits are associated with the 1 st Grote Mandrenke (or St. Marcellus’ flood ), an extreme storm surge event in 1362 AD. Our results, for the first time, provide geological evidence of this 1362 AD storm surge for the Wadden Sea of North Frisia. Moreover, marshland on Hallig Sudfall dating to the 17 th -18 th cent. AD was found covered by a thick layer of storm surge sand and shell debris which seems to be associated with one of the major storm event that hit the German North Sea coast in modern times, e.g. the 2 nd Grote Mandrenke (or Burchardi flood ) in 1634 AD or the Christmas flood in 1717 AD.

Hydrodynamic numerical models are essential in modern tsunami hazard assessment. They allow the economical simulation of possible tsunami scenarios for areas at risk and provide reliable and detailed insights into local onshore dynamics. This is especially true when simulations are calibrated with field traces of past tsunami inundation events. Following this approach, the current study focuses on palaeotsunami events indicated by sedimentary and geomorphological field traces in the northern Gulf of Kyparissia (NW Greece). Based on three different digital elevation models (DEM) – reflecting the recent and two palaeotopographies – various tsunami wave constellations according to the solitary and N-wave theory are numerically simulated. The main objective is to investigate the effects of both, different palaeotopographies and boundary conditions on the tsunami onshore response in the numerical model. Tsunami landfall related to N-waves is found to be considerably stronger compared to solitary waves. This phenomenon, known as the N-wave effect, is demonstrated for the first time in a specific study area. Inundation dynamics are even stronger affected by the different palaeotopographies, which is due to substantial vertical crust movements in the northern Gulf of Kyparissia considered in the palaeo-DEMs. By applying different waveforms and palaeotopographies, the model achieves close agreement with field observations, altogether revealing a significant tsunami hazard for the Gulf of Kyparissia, which is in contrast to conventional numerical studies of the area. The marked differences between the presented scenarios emphasise the need to consider a wide variety of possible hydrodynamic boundary conditions and probable topographical conditions in order to find scenarios in plausible accordance with palaeotsunami field traces. Once a plausible scenario is found it can be applied to the recent topography in view of a reliable modern hazard assessment.

In this paper, we present for the first time geomorphological, sedimentary and microfaunal evidence of palaeotsunami impact on Corfu (Ionian Islands, Greece). The island of Corfu is located in an area of exceptional tectonic stress: towards the south, the African oceanic plate is being subducted underneath the Aegean plate, whereas towards the north, the Adriatic and European plates form a continental collision zone. Recent publications provide evidence of earthquake related co-seismic movements that potentially trigger extreme wave events as well as relative sea level fluctuations. In this context, we investigated two selected near-coast geological archives – the Chalikiopoulou Lagoon in the east and the Korission Lagoon in the southwest of Corfu Island. Our results clearly document that the eastern as well as the southwestern coasts of Corfu were repeatedly affected by palaeotsunami impact during the Holocene. With regard to the local topographical constellation and the recent geomorphodynamic potential of each study area, evidence of high-energy wave impact is based on the stratigraphical and microfaunal record of selected vibracoring sites as well as on numerical modelling results. It is concluded that the eastern coast of Corfu is preferably affected by high-energy wave impacts from a southern direction. Such impacts are most likely related to teletsunamis from the major seismical zone of the Hellenic Trench. In contrast, the southwestern coast of Corfu is endangered by impacts from both western and southern directions. Such impacts may comprise teletsunamis triggered in the Hellenic Trench or the Etna regions but may also be caused by local submarine landslides at the steeply sloping continental shelf directly west of Corfu. Our study builds a bridge between palaeotsunami-research conducted in the southern Ionian Sea and the Adriatic Sea and allows to better discriminate between the effects of teletsunamis and locally triggered events within one of the seismically most active regions in the eastern Mediterranean.

The southwestern coast of Crete, one of the most seismically active regions in Europe, experienced co-seismic crust uplift by 9 m during the Ms = 8.3 mega-earthquake that struck the eastern Mediterranean world on 21 July AD 365. An associated tsunami event caused thousands of fatalities and destroyed many coastal settlements and infrastructure between the Levante in the east and the Adriatic Sea in the northwest. So far, coastal sedimentary archives in southwestern Crete including distinct palaeotsunami fingerprints are rarely investigated. Therefore, a multi-proxy study including sedimentological, geochemical, geochronological, and microfaunal methods was conducted in order to detect onshore coastal sedimentary archives that functioned as fine sediment traps and document palaeotsunami imprint. We found adequate archives at the Sougia and Palaiochora coastal plains that were used to reconstruct the palaeogeographical evolution and the palaeoseismological history of SW Crete during the late Holocene. Our studies revealed distinct geomorphological, sedimentological, geochemical, and microfaunal traces of high-energy impact from the marine side related to seismic events. At the Sougia coastal plain a sheet of fine sand with a neat microfossil and geochemical fingerprint was found sandwiched between underlying pre-tsunami muds and overlying post-tsunami colluvial silt. In the Palaiochora coastal plain, tsunami overflow of a flat Neogene bedrock platform led to the accumulation of sand-dominated deposits that were subsequently covered by colluvial material from the adjacent hillslopes. Based on radiocarbon and luminescence dating approaches, it is shown that the AD 365 tsunami event is the best-fit candidate for the tsunami-related sediments deposited at both, Sougia and Palaiochora. This study, for the first time, presents multi-proxy evidence of the AD 365 tsunami imprint on fine-sedimentary archives along the western and southwestern coast of Crete.

In regions with a short historical tsunami record, the assessment of long-term tsunami risk strongly depends on geological evidence of prehistoric events. Whereas dating tsunami deposits is already well established, magnitude assessment based on remaining sedimentary structures is still a major challenge. In this study, two approaches were applied to deduce transport processes and hydrodynamic parameters of tsunami events from onshore deposits found in the coastal plain of Ban Bang Sak, SW Thailand: (1) The maximum offshore sediment source was determined using granulometry, geochemistry, mineralogy and foraminifera of the tsunamites, and reference samples from various marine and terrestrial environments, and (2) the onshore flow velocities and flow depths of associated tsunami waves were estimated by means of sedimentation modelling. In the case of the Indian Ocean tsunami (TOT) of 2004, modelled flow velocities of 3.7 to 4.9 m/s, modelled onshore flow depths of up to 5.5 m, and a sediment source from offshore areas shallower than a 45-m water depth-including littoral sediments transported as bedload and suspended load from the shallow subtidal zone-are in agreement with quotations based on survivor videos and posttsunami surveys. For a 500- to 700-year-old predecessor, comparable flow velocities and flow depths of 4.1 to 5.9 m/s and 4.0 to 7.5 m, respectively, were modelled, indicating a similar magnitude as the IOT 2004. Comparable values of maximum transport distance and depth of wave erosion were also found. In the case of three older tsunami candidates, dated to 1180 to 2000 cal BP, the deposits indicate partly similar source areas with water depths of less than 45 m and partly shallower source areas restricted solely to the beach. Whereas the former tsunamis are interpreted as events similar to 2004, the latter are more likely storms or tsunamis of a lower magnitude.

The coastal deposits of Bonaire, Leeward Antilles, are among the most studied archives for extreme-wave events (EWEs) in the Caribbean. Here we present more than 400 electron spin resonance (ESR) and radiocarbon data on coarse-clast deposits from Bonaire’s eastern and western coasts. The chronological data are compared to the occurrence and age of fine-grained extremewave deposits detected in lagoons and floodplains. Both approaches are aimed at the identification of EWEs, the differentiation between extraordinary storms and tsunamis, improving reconstructions of the coastal evolution, and establishing a geochronological framework for the events. Although the combination of different methods and archives contributes to a better understanding of the interplay of coastal and archive-related processes, insufficient separation, superimposition or burying of coarse-clast deposits and restricted dating accuracy limit the use of both fine grained and coarse-clast geoarchives to unravel decadal- to centennial-scale events. At several locations, distinct landforms are attributed to different coastal flooding events interpreted to be of tsunamigenic origin. Coastal landforms on the western coast have significantly been influenced by (sub)-recent hurricanes, indicating that formation of the coarse-clast deposits on the eastern coast is likely to be related to past events of higher energy.

The Lefkada–Preveza coastal zone, NW Greece, is characterised by an active barrier system and related extensive beachrock sequences. Besides the gradual coastal processes of longshore drift and spit evolution, the presence of active tectonics and the occurrence of tsunamis have been documented in previous studies and are part of the coastal geomorphological system. In this paper, we present the results of detailed multi-proxy sedimentological and geomorphological investigations carried out along the northern part of the barrier system and in back-beach positions. Our findings suggest that extreme wave events contributed to coastal and environmental changes and involved temporary breakdown of the barrier system. Sedimentary findings suggest that one generation of event deposits may be related to the 365 AD Crete earthquake and associated tsunami. According to our results, the Lefkada coastal system formed by the interaction of both long-term, gradual and sudden, impulsive littoral geomorphodynamics. Extreme wave events are assumed to have played a significant role in the evolution of the present coastline, acting as recurrent impulsive disturbances of the coastal system. Subsequently, the onset of long-term gradual coastal processes, such as longshore drift, re-established a state of natural coastal balance by re-arranging the coastal sediments.

This paper addresses the obvious controversy between the so far published sea level curves of the Black Sea and the Mediterranean. It starts with a discussion of the methods of reconstructing sea level curves, the evaluation of sea level indicators, and the application of the radiocarbon dating method. At least since 7500 BP, when the Black Sea and the Mediterranean were connected, both water bodies must have reacted synchronously on glacio-eustatic changes. It is documented that none of the Mediterranean sea level curves shows the major wiggles postulated for the Black Sea which are supposed to reflect trans- and regression cycles. The very shallow bathymetric condition of the Azov Sea and the northern Black Sea should have led to considerable and traceable shoreline displacements. There is neither archaeological nor historical evidence of mid- and late-Holocene regressions of several meters. The tectonic setting of the Black and Azov seas implicates that the tectonic signal often overrides the eustatic one. Therefore, only local sea level curves can be established. In this paper, based on vibracores, a locally valid sea level curve for the Taman Peninsula is demonstrated. Layers of paralic peat were used as sea level indicators and for 14 C dating. The shape of this curve follows the one known from the Mediterranean. This study also revealed that the present peninsula of Taman evolved out of a former archipelago.

This paper gives evidence of multiple tsunami inundation of the Sound of Lefkada (NW Greece) since the mid-Holocene based on the analysis of sediment cores by means of geomorphological, sedimentological, geochemical, micromorphological and micropalaeontological methods. Layers of sand, gravel and shell debris, mostly unsorted, were found intersecting autochthonous lagoonal muds of the sheltered and quiescent inner-sound environment. They are further characterized by erosional unconformities at their base, rip-up clasts from the underlying sediments, fining upward sequences and an upward increase in sorting. The coarse grained high energy deposits include macro- and microfaunal remains typical of open-marine, partly even deep-water conditions which underlines their allochthonous character. Several distinct event layers indicate multiple tsunami passage across the sound. Earth resistivity measurements and vibracore transects revealed that the entire sound has been affected by catastrophic wave events. Thin sections of tsunami-influenced sediments found in lateral parts of the sound show a mixture of marine, lagoonal and terrigenous material. The inner Sound of Lefkada, well protected against storms, thus represents an excellent trap for tsunamigenic deposits. A preliminary local tsunami geochronology is based on 9 radiocarbon dates and diagnostic ceramic fragments. Several early tsunami impacts hit the sound between the 6th and 3rd millennium BC. Younger events seem to be consistent with tsunami landfalls that hit adjacent areas around 1000 cal BC, 395–247 cal BC as well as in Roman and medieval times. Vibracore data document an isthmus-like shallow-water environment which existed in the central sound and which was repeatedly inundated by tsunami wave action. Multiple tsunami passage eroded a natural channel which, we suggest, is the precursor of the famous waterway excavated by the Corinthians in the 7th century BC. Based on historical data, it is concluded that the navigable channel across the sound was repeatedly choked with sediments by tsunamigenic inundation during the following centuries. This study reveals a high tsunami risk for the Sound of Lefkada with at least one strong event in every 500–1000 years.

This paper presents, for the first time, detailed geomorphological, sedimentological, geoarchaeological, geophysical and geochemical evidence of a strong tsunami impact on the Bay of Aghios Nikolaos and its environs (NW Greece) during Classical–Hellenistic times. Tsunamigenically dislocated beachrock slabs found on top of the Santa Maura beach ridge complex are closely interrelated to adjacent coarse-grained washover fan deposits encountered in vibracores and detected by earth resistivity measurements. Based on detailed topographic surveys and geomorphometric investigations, it was possible to localize areas of high intensity overflow. Underwater studies revealed that the central and northern parts of the former Plaka beach ridge were completely destroyed by tsunami impact. Loose littoral deposits were flushed into the Bay of Aghios Nikolaos and mega blocks of the underlying beachrock structure were dislocated landwards. Tsunami landfall occurred all along the eastern and northern shores of the bay where deposits, partly weathered and associated to archaeological findings, were found. Runup was estimated to minimum values between 2–3 m and 4–6 m a.s.l. Crosschecking the results of radiocarbon analyses with archaeological ages from five sites allowed to date the strong tsunami event to the time period between 395 cal BC and 247 cal BC. Due to the funnel-like contour of the coastline, the area is extremely sensitive to tsunami events of mid to high magnitude and high frequency.

The shipsheds of the ancient seaport Oiniadai (5th-3rd cent. BC), today located in the central Acheloos River delta on top of the Trikardo hills 9 km inland, document considerable coastal changes. ...

The eastern Acheloos River delta and the Lagoon of Etoliko have undergone broad environmental changes since the mid-Holocene. In this study, sedimentological, geochemical, geophysical, micromorphological, computer tomographical, micro- and macrofaunal, and archaeobotanical methods were applied to determine lateral and vertical facies patterns of near-coast geological archives. We present the stratigraphic sequences of 13 vibracores and one 9-m-long sediment core from the Lagoon of Etoliko. Geochronology was based on 28 radiocarbon dates. Sea-level fluctuations were detected by means of sedimentological sea-level markers. The relative sea level rose from 12.70 m below sea level (b.s.l.) at 6150 cal BC to 7.90 m b.s.l. by 4750 cal BC and 2.60 m b.s.l. by 500 cal BC. The maximum rate of rise occurred until 5550 cal BC, and the lowest, between Helladic and Byzantine times. Delta growth clearly increased after the relative sea-level rise decelerated around 5500 cal BC. Palaeogeographical maps for diff...

This study presents relative sea level (RSL) curves for seven coastal areas in Akarnania and the northwestern Peloponnese (NW Greece) since the mid-Holocene. RSL fluctuations are deduced from 48 14C-AMS dated sedimentological sea level markers from 27 vibracores drilled in near-coast geological archives as well as from six geoarchaeological sea level indicators of known ages. Seven palaeo sea level curves including uncertainty bands are reconstructed for a coastal zone spanning a distance of 150 km. Considerable intra-regional differences in sea level evolution exist. These differences are mainly due to tectonic reasons. In general, RSL in northwestern Greece has never been higher than today. Rates of local sea level rise were highest until 5500–5000 cal BC (up to 12.3 m/ka) and lowest during 4000–500 cal BC (0.2–1.4 m/ka). During the past 2500 or so years, RSL has accelerated anew (0.7–2.7 m/ka). Calculating differences between local mean sea level curves provides quantitative information on intra-regional differences of tectonic activity. The coastal plains of Palairos and Elis show signs of uplift, whereas the Mytikas and Boukka plains are strongly subsiding. Compared to other areas of the eastern Mediterranean, northwestern Greece has been subject to significant net long-term subsidence. Regional tectonic events (RTEs) were detected for the time around 4000, 2500, 500 and 250 cal BC as well as around 250 and 1250 cal AD. RTEs are characterized by changes of uplift/subsidence rates or by the redirection of local tectonic movements. The question if some of the RTEs were of a supra-regional nature is still open. From a geodynamic point of view, the results presented show that Akarnania's southwestern fringe is being downwarped while the tectonic block as a whole is moving towards the southwest. Strongest subsidence rates are observed for central Akarnania. At Akarnania's fringes, subsidence is reduced by the influence of strong uplift of adjacent areas such as around Preveza and the northern Peloponnese.

This paper deals with Holocene coastal changes of the Astakos plain in Akarnania, NW Greece. Palaeoenvironmental scenarios are based on the analysis of the lateral and vertical distribution patterns of sedimentary facies. Sediments from vibracorings were studied using geomorphological, sedimentological, microfaunal, palaeobotanical and geochemical methods. A geochronostratigraphy was achieved by 14C-AMS-dating of organic matter. We present palaeogeographical maps for different points in time since the mid-Holocene. The evolution of the coastal area was generally controlled by the migration of a complex system of a shallow marine embayment, an adjacent lagoonal environment and an adjoining coastal lake forced by the interaction of sea level rise, tectonic movements, and sediment supply from the hinterland. The maximum transgression of the Ionian Sea took place at circa 5500 cal BC reaching approx. 1.1 km inland. The lagoon as well as the coastal lake had their largest dimensions around 4500 cal BC indicating a more humid climatic period. In the course of a long-lasting regression, an asymmetric sedimentation pattern developed. Around 2500 cal BC it was characterized by strong fluvial deposition of the Xeropotamos in the western plain and a small and narrow marine embayment with associated lagoonal to limnic coastal water bodies in the eastern plain. The latter were related to karstic springs draining the adjacent Rigani ridge. Around 500 cal BC the coastline lay about 200 m landward of its present position. Possible harbour sites for the ancient polis of Astakos are (a) the area of modern Astakos where a mole in a position seawards of the present coast would have guaranteed deep water conditions for anchoring, or (b) the southeastern fringe of the plain where deep water prevailed and the nearby freshwater outlet protected the site from rapid siltation. We found increased torrential activity (i) for the 6th–5th millennium BC, (ii) for the 2nd half of the 1st millennium BC until Roman times, and (iii) at the end of the 19th century AD. At least the two younger phases are mostly due to anthropogenic soil erosion. Between the 4th and the 2nd millennium BC a period of ecological stability existed. Relative changes in sea level for the Bay of Astakos were reconstructed for the first time. Since the mid-Holocene, the relative sea level has never reached a higher position than today. It rose from 12.50 m b.s.l. at 6200 cal BC via 2.20 m b.s.l. at 500 cal BC to its present level. Besides eustatic reasons, tectonic subsidence due to the half graben structure of the area is the main trigger of the relative rise in sea level.

Sediments from the Palairos coastal plain (Akarnania, northwest Greece) were studied to establish paleogeographical scenarios of Holocene landscape evolution. Near coast vibracore profiles revealed regressive sedimentary sequences, the base of which is dominated by marine sand and/or lagoonal mud. The middle and upper parts of the sequences are made up of lacustrine mud and fine- to coarse-grained alluvial deposits reflecting the increased activity of torrential river systems. In the southern plain, marine sediments of the maximum incursion of the Ionian Sea were found 1 km inland and date from the seventh millennium B.C. This proves that the Lake Voulkaria in the northern plain does not represent the remains of a former marine embayment. Subsequently, a large lagoon developed and existed until the fourth millennium B.C. The central plain was mainly exposed to subaerial conditions when man started to colonize the area in the seventh millennium B.C. In the fifth millennium B.C., the Palairos lagoon turned into a freshwater lake. When ancient Palairos was founded in the 6th century B.C., shallow lakes and swamps dominated the southern and central parts of the plain. At that time, a narrow canal-like connection between the Bay of Palairos-Pogonia and the Lake Voulkaria existed and was possibly used as a slipway for ships. During the last 4000 years, the Palairos plain experienced strong input of fluvial sediments which finally filled up the coastal lake as well as the swampy grounds.