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Detailed geoarchaeological studies were conducted at the Groβkrotzenburg floodplain (Southern Hesse, Germany) in order to reconstruct the fluvial palaeogeography and search for Roman harbour installations. Another objective was to reconstruct the local flood history based on stratigraphic and geochronological data. Prospection based on electrical resistivity tomography, vibracoring and direct push electrical conductivity logging were carried out to detect and analyze subsurface stratigraphies. Altogether, 6 sediment cores, up to 7 m long, were drilled along transects along and perpendicular to the present course of the River Main. Based on sedimentological and geochemical data, we classified four sedimentary units. Vibracore data helped to detect the pre-Holocene bedrock topography and to differentiate between sedimentary facies. We present geophysical, sedimentary and geochronological evidence of a river channel right in front of the Roman fort that was probably active during Roman times. Moreover, we found another bridge pier candidate in the prolongation of a well documented Roman bridge. Our findings further indicate that the northern riverbank has shifted towards south since Roman times. However, neither sedimentary nor archaeological evidence for harbour installations could be brought to light. Nevertheless, we assume that conditions favorable of a river harbour, namely permanent water flow and sufficient water depth, were guaranteed in front of the fort where an undercut slope was probably already existing during Roman times. Several sequences of coarse-grained, sandy to gravelly river deposits were found associated with major flood events that affected the site at Groβkrotzenburg during late Medieval and modern times. At that time, central Germany was repeatedly influenced by extreme meteorological conditions and associated extreme runoff events. Based on radiocarbon data we were able to define two periods of major flooding, namely between 1435 and 1484 cal AD and 1646–1792 cal AD. These periods are contemporaneous with periods of increased flood frequency in Central Europe, derived from historical sources, namely 1430–1460 AD and 1730–1790 AD. Based on sedimentary and geo-chronostratigraphic evidence, major flood events detected at the Groβkrotzenburg alluvial plain are most probably related with the AD 1480, AD 1573 and AD 1780 events known from historical records. Our results document that few historical flood events controlled the overall development of the fluvial landscape at Groβkrotzenburg at least since Roman times until the late 19th century, namely by eroding pre-existing fluvial deposits, accumulating thick sequences of event deposits and narrowing the riverbed. Since the late 19th century, river regulation measures severely changed the hydrological conditions of the River Main.

International audience; After the 2004 Indian Ocean (IOT) and the 2011 Tohoku-oki tsunamis, new research in tsunami-related fields was strongly stimulated worldwide and also in the Mediterranean. This research growth yields substantial advancements in tsunami knowledge.Among these advancements is the “Paleotsunami” research that has marked particular progress on the reconstruction of the tsunami history of a region. As an integration of the historical documentation available in the Mediterranean and the Gulf of Cadiz areas, geological and geoarchaeological records provide the insights to define the occurrence, characteristics, and impact of tsunamis of the past. Here, we present the recent advancements done for both the onshore and offshore realms.As for the onshore, we discuss case studies dealing with recent high-resolution works based on: a) direct push in situ sensing techniques, applied to identification and characterization of typical paleotsunami deposits features; b) combined XRF-X-CT approach, implemented for the identification of fine-scale sedimentary structures useful for the definition of the causative flow dynamics; c) the geoarchaeological “new field” contribution, with the development of specific diagnostic criteria in search for tsunami impact traces in archaeological strata; d) comparison of multiple dating methods and of different modeling codes for the definition of the potential source for the displacement of boulders of exceptional dimension, identified by 3D size calculation.As for the offshore advancements, we present case studies focusing on the recognition of tsunami deposits and their sedimentary traces in the geological record from the nearshore, thanks to diver-operated coring equipment, down to the continental slope, by means of vibracorer and long gravity core sampling in deeper areas. The examples provided show a multiproxy approach with a high potential of retrieving a complete record of paleotsunami traces at least during the Holocene. This is based on the combination of multidisciplinary approaches including X-ray imaging, high-resolution measurement of physical properties, X-ray fluorescence data, grain-size analysis, micropaleontology, palynological content, isotopic and optically stimulated luminescence dating methods.

Frontiers in Earth Science 9, 1-17 (2021). doi:10.3389/feart.2021.599986, Published by Frontiers Media, Lausanne

Loess-Palaeosol-Sequences (LPS) in the Central European region provide outstanding terrestrial polygenetic and multiphase archives responding to past climate and environments over various spatial and temporal scales. As yet, however, the geomorphological and pedogenic processes involved in LPS formation, and their interplay with changes in ecological conditions, impede robust correlation with other palaeoenvironmental archives. The Schwalbenberg LPS, which drape a hillslope in the Middle Rhine Valley in western Central Europe, provide unique high-resolution records highly suitable for investigating the processes involved in their formation and the relationship to climatic influences during the Upper Pleistocene. Here we present the first comprehensive multi-proxy dataset for the Schwalbenberg LPS over four dimensions. We undertake systematic analyses along a representative slope transect using surface-based geophysical prospection in combination with Direct Push hydraulic profiling to characterise the subsurface stratigraphy in detail. We integrate selected sedimentological and geochemical proxy data from three long sediment cores and two profile sections to build a complete stratigraphical succession for the Schwalbenberg LPS. We show that the transect approach allows quantification of different formation phases, whether accumulative, erosive or pedogenic in character. In so doing we overcome the bias inherent in studies of individual sections and enable robust and reliable correlation with other climate archives. For the time interval ~ 80–15 ka BP correlation of combined lithostratigraphic features and organic carbon contents from Schwalbenberg with the Sofular and NGRIP δ18O-records can be established at millennial to centennial scale resolution, highlighting the sensitivity of western European LPS to the Atlantic-driven climate oscillations in much more detail than in any other terrestrial archive known in the region so far.

We present a case study of a bog showing how an integrated approach of multi-method geophysical sounding and local soil sampling can be used to identify, differentiate, and map organic sediments. Our study is based on ground-penetrating radar (GPR), electrical resistivity tomography (ERT) and shear-wave seismic (SH seismic) profiling applied to sediments of the former Lake Duvensee (northern Germany), nowadays a bog. This is a well-known locality for remains from the Mesolithic hunter-gatherers&rsquo, occupation that has been attracting archaeological and geoarchaeological research for100 years. The bog is embedded in low conductive glacial sand and is characterized by layers of different gyttja sediments (detritus and calcareous). The present study was conducted in order to identify the bog morphology and the thickness of the peat body and lake sediments, in order to understand the basin evolution. To validate the geophysical results, derived from surface measurements, drilling, soil analyses as well as borehole guided wave analysis of electromagnetic waves and Direct-Push (DP-EC) have been carried out and used for comparison. It turned out that each method can distinguish between sediments that differ in grain size, particularly between peat, lake sediments (gyttjas and mud) and basal glacial sand deposits. GPR is even able to separate between strongly and weakly decomposed peat layers, which is also clear considering resistivity variations in the ERT computation. From the association between geophysical properties and sediment analysis (e.g., water content and organic matter) different gyttjas were distinguished (coarse and fine) and seismic velocity was correlated to bulk density. Moreover, GPR and SH-wave seismics present different resolutions, confirming that the latter allows measurements, which are more focused on determining the extension of basal sand deposits, the depth of which is difficult to reach with GPR. Representative values of electrical resistivity, dielectric permittivity, and shear wave velocity have been determined for each sediment type and are therefore available to complete the investigation of wetland environments. Fine grained lake sediments were difficult to differentiate by the applied methods. This could be a result of high ionic concentration within the permanent groundwater body, partly masking the sediment properties.

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 (Hadler et al. 2019) 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 silted up before the harbour at Portus was established as previously assumed by other authors. Actually, the western front of the navalia-temple complex was hit by an extreme wave event, leaving a sand layer approx. 0.5 m thick, at or shortly after AD 355–363 which led to the final abandonment of Ostia’s western river harbour. This event is interpreted as a tsunami that may have hit the wider coastal region.

The inversion of geoelectric data is nonunique. Therefore, electric resistivity tomography (ERT) usually results in different subsurface models that fit observed apparent resistivity values equally well. To reduce the uncertainty, constraints on the geometry and resistivity of subsurface structures can be incorporated into the ERT inversion. We test different ways of constraining ERT by applying (1) improved starting models, (2) structural constraints, and (3) structural and resistivity constraints. A priori information is needed for these approaches, which is acquired from direct push electrical conductivity (DP-EC) logs and vibracores in our study. We found that adapting high vertical resolution of DP-EC logs to coarser ERT resolution requires blocking of the logs. These blocked logs can be used for constraining the ERT inversion with resistivity and structural constraints along so-called regions around the log locations, which was found to be the best approach. In this case, ground truthing with additional DP-EC logs that were not used for constraining showed the lowest root-mean-square error between logs and ERT model.

We performed a combined geophysical and geoarchaeological survey of the harbour of ancient Ostia, Italy, to investigate the extent of the former harbour basin, the sedimentary infill and possible building remains around the harbour. Besides geoarchaeological results the paper highlights the advantage of combining vibracore drilling with different geophysical prospection methods, which are sensitive to different physical soil parameters. Geophysical methods applied were electrical resistivity tomography (ERT), ground penetrating radar (GPR) and seismics with shear and compressional waves. The extent and shape of the harbour basin were determined by ERT profiling. The ERT profiles were compiled into a 3D-model showing that the early lagoonal harbour basin was at least 100 m × 50 m wide. Its southern border was confirmed by GPR measurements clearly imaging the former land-water transition and the onset of ancient onshore building construction. At its eastern border a consolidated horizon could be mapped in 2–3 m depth by compressional wave tomography. This horizon most likely represents a cemented ramp, a small part of which had been excavated in a previous study. The sedimentary fill of the former harbour basin was investigated by a combination of vibracoring, ERT and seismics. The ERT profiles serve for inter- and extrapolating the vibracore stratigraphy from the coring locations over the whole harbour area. It turned out that one sedimentary unit, which is important for the harbour development, could not be resolved by ERT but clearly shows up in seismic velocity-depth profiles instead. It is a thin coarse-grained high-energy layer in 1–2 m depth, which was caused by a tsunami according to a previous study. This layer separates two harbour phases: an older lagoonal harbour phase underneath and a younger fluvial harbour phase above it. The high-energy layer represents a thin band of 100% increased shear wave velocity compared to the more fine-grained layers, in which it is embedded. This study is the first to show that tsunami-type sedimentary layers may be mapped by shear wave profiling.

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.

The 1717 Christmas flood is one of the most catastrophic storm surges the Frisian coast (Netherlands and Germany) has ever experienced. With more than 13,700 casualties it is the last severe storm surge with a death toll of this order. At the same time, little is known about the hydrodynamic conditions and the morphological effects associated with this storm surge.In this study, 41 potential dyke failures in the Province of Groningen (Netherlands) associated with the 1717 Christmas flood were systematically reconstructed and mapped by using historical maps and literature and by analysing the recent topography in search of typical pothole structures and sediment fans. The dimensions of the sediment fans as derived from the topography show a good accordance with the dimensions documented by vibracore profiles, direct push tests and electrical resistivity tomography data taken at three fieldwork sites. Moreover, the fan dimensions closely agree with the dimensions as simulated using a process-based morphodynamic numerical model for one of the three sites, the village of Wierhuizen. Consequently, the recent topography is still indicative for the locations and dimensions of dyke failures and sediment fans associated with the 1717 Christmas flood. Considering the large number of detected dyke failures (41) and the large dimensions of the potholes and particularly of the sediment fans up to a few hundred metres wide and up to 0.7 m thick, this study proves significant morphological effects of the 1717 Christmas flood on the mainland of the Province of Groningen.Based on the numerical simulation approach and the comparison with field data and field observations, a maximum seaward water level of 5 m NAP for the dyke failure at Wierhuizen during the Christmas flood can be derived. A similar maximum water level is indicated for the two other fieldwork sites Vierhuizen and Kohol, which is in good agreement with the maximum storm surge level of 4.62 m NAP historically documented for the city of Emden located almost 50 km to the east of Wierhuizen.The results of the current study demonstrate that the reconstruction of historical dyke failures based on (i) historical sources, (ii) recent lidar/high-resolution topographical data, (iii) multi-proxy sedimentary field data and (iv) hydro- and morphodynamic numerical simulations is a highly promising approach to derive hydrodynamic conditions and the morphological onshore response of the 1717 Christmas flood in the Province of Groningen. This knowledge is essential to improve our understanding of extreme storm surge dynamics, their influence on the coastal landscape and the associated hazards for the coastal population.

The Late Bronze Age (LBA) tsunami and the A.D. 365 tsunami are supposed to have affected the northern coasts of Crete. However, near-coast sedimentary archives have been rarely investigated in this area, and sedimentary archives including palaeotsunami fingerprints are still unknown. The main objective of our research was to search for appropriate tsunami sediment traps in order to gain detailed insights into the Holocene palaeotsunami history of northern Crete. We found an excellent fine sediment archive near Pirgos, located to the west of Rethymnon. Based on a multi-electrode geoelectrical survey and an 11-m-deep sediment core, we analysed the event-geochronostratigraphical record by means of sedimentological, geochemical, geochronological, geomorphological, and microfossil investigations. The Pirgos record revealed a thick unit of homogeneous mud of a lagoonal environment starting ~6000 years ago. The lagoon was affected by five high-energy events, leaving layers of allochthonous sand. Microfossil analyses of these layers revealed a mixed foraminiferal assemblage including species from brackish habitats but also displaced and transported species from open marine and deep-water environments. Considering sedimentary characteristics, the local wave climate of the Cretan Sea, and the overall geomorphological setting, we interpret these layers as related to extreme wave events (EWE). Based on a local radiocarbon age-depth-model, we identified one EWE layer as a reliable candidate for the LBA Santorini tsunami. Another EWE layer is most probably associated with the A.D. 365 tsunami. This EWE ended abruptly the lagoonal conditions at Pirgos because of to the 1.64 m coseismic uplift at the site. The Pirgos lagoon existed between the first half of the 6th mill. B.C. and (at least) the end of the 2nd mill. B.C. We found that the area around Pirgos has continuously subsided over 3000 or so years, reflecting constant tectonogeomorphological conditions dominated by the nearby subduction zone between the Aegean and African plates.

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.

Non-invasive geophysical methods have been increasingly applied in geoarchaeological research commonly showing the need of data calibration based on stratigraphical information deduced from outcrops or sediment cores. In this contribution, a methodological approach combining two-dimensional (2D) electrical resistivity tomography (ERT) and stratigraphical data based on coring and, for the first time in geoarchaeological research, direct-push electrical conductivity (DP-EC) logging is presented and discussed. The approach yields high resolution data based on studies of two different types of archives, the Holsterburg site in central Germany located in a fluvio-terrestrial zone and the Corfu City site in Greece located in a near-coastal zone. It is shown that DP-EC logs trace fluctuations over grain size in high resolution which reflect changes of depositional conditions in the course of time. In addition, constraints from DP-EC logs in the form of layer interfaces and electrical resistivities were incorporated into the ERT inversion process minimizing the ambiguity of inversion results. It is shown that incorporating regions with certain starting resistivities based on DP-EC logs exceed the advantage of using layer interfaces alone. It is concluded that in future geoarchaeological and geomorphological studies a combined application of coring, DP-EC logging and ERT measurements should be considered as a standard approach towards a more comprehensive stratigraphical characterization of the shallow subsurface. Copyright (c) 2016 John Wiley & Sons, Ltd.

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.

© 2018 Elsevier Ltd and INQUA. Reconstructing dust Mass Accumulation Rate (MAR) from loess deposits is critical to understanding past atmospheric mineral dust activity and requires accurate independent age models from loess deposits across Europe and Asia. Previous correlations of loess in Europe and China have tended to focus on multi-millennial timescales, with no detailed examination of dust MAR at the two ends of the Eurasian loess belt on shorter, sub-orbital scales. Here we present a detailed quartz optically stimulated luminescence (OSL) chronology from the Serbian Titel Loess Plateau (Veliki Surduk loess core) and the Chinese Loess Plateau (Lingtai section). The luminescence ages pass internal tests and show consistent increases in age with depth, with no obvious major hiatuses. However, as reported before, it seems the quartz OSL technique is only capable of accurate age determination up to accrued doses of ca. 150 Gy (ca. 30-40 ka) due to approaching field saturation of the quartz OSL signal. Two age-depth models were used to reconstruct dust MARs, where one utilises OSL data solely and the other additionally makes assumptions about sedimentation rates. Although short-term fluctuations in MAR are model dependent, general MAR patterns between the two sites are very similar, with peak MAR occurring rather late in the last glacial (ca. 13-25 ka). This suggests that at least broad scale trends in dust activity within the last glacial period may be similar at a continental scale.

In antiquity, the harbour-city of Corcyra (modern: Corfu) was a prevailing naval power in the Mediterranean and had several harbours to host a considerable fleet. Today, these harbours are totally or partly silted and concealed under modern urban infrastructure. Comprehensive geoarchaeological studies were conducted on the northeastern fringe of the Analipsis Peninsula where excavations have revealed the archaeological remains of a massive quay wall (Pierri and Arion sites). These remains are located east of known ancient harbour structures that belong to the Alkinoos Harbour. Our study aimed to reconstruct the palaeoenvironmental setting of the harbour facilities at the Pierri site, including the analysis of the local sedimentary record in order to detect and differentiate natural and man-made triggers that caused environmental shifts. At the Pierri site, we found geoarchaeological evidence for an ancient harbour basin related to the prominent quay wall. Associated harbour sediments indicate a protected harbour which was developed from an open shallow marine environment, most probably by the construction of breakwaters. Harbour deposits were dated using radiocarbon analyses and diagnostic ceramic fragments to the 4 th to 3 rd cent. BC. This is in good agreement with the age of the harbour installations as such archaeologically assigned to the Classical and Hellenistic period. The Pierri site was possibly in function as a harbour facility even before the 4th cent. BC. In any case, it was strongly hit by an earthquake and associated tsunami event during Classical to Hellenistic times. By this event, the harbour was uplifted and covered by event deposits so that it was not usable any more. It was subsequently buried by anthropogenic and colluvial sediments. Overall, the Pierri coastal archive allowed to identify three distinct tsunami landfall events, namely before 2483–2400 cal BC (event I), after 2483–2400 cal BC and before 370–214 cal BC (event II), and during Classical to Hellenistic times, most probably between the 4 th and 3 rd cent. BC (event III). Another tsunami event (event IV) potentially hit the site when it was dry land. Ages of tsunami events I–II and candidate tsunami IV are consistent with tsunamis known from the coasts of western Greece and southern Italy and where thus classified as supra-regional tele-events. Event III was identified as associated to a local earthquake and tsunami by which Corfu Island was uplifted and, at the same time, tilted with a vertical offset of 1.74 m from W to E.

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.

International audience