Tracing the spatial and temporal variabilities of tsunamites on Crete Island (Greece) by sedimentological, geophysical and geodetical methods
Final Report Abstract
Since the AD 365 earthquake and co-seismic uplift, Crete's southwestern parts have been exposed to intense erosion. So far, near-coast sedimentary archives have been rarely investigated and sedimentary archives including palaeotsunami fingerprints are unknown. We were able to detect nine geoarchives along the southern and northern coast of Crete that turned out to be appropriate to decipher tsunami signals in the fine-sedimentary records of coastal Crete. For the first time, we detected geoscientific evidence of the AD 365 tsunami impact at the southwestern coast of Crete. Moreover, we found out that older tsunami signals seem to have been erased by the AD 365 event. Also for the first time, tsunamite candidates in the fine-sedimentary record of nearcoastal archives were found at the northern coasts that can be associated with the LBA Santorini eruption and tsunami. Comprehensive fieldwork and detailed laboratory analyses of sediment samples from different types of geo-archives let us decipher the spatial variability of tsunami signatures, for example the Sougia and Palaiochora coastal plains, the area around Rethymnon, Plakias and Agia Fotini in the south. Microfaunal analyses turned out to be a reliable tool to identify tsunamites within the sedimentary record. Depending on the type of geo-archive and its tectonic background, weathering processes have more or less influenced the conservation potential of foraminifera. Tsunami deposits and the way they are conserved in the coastal landscape are strongly dependent on the local relief controlling tsunami inflow and backflow dynamics as well as on the intensity of post-depositional processes. Tsunami signatures as such strongly vary and are intimately related with geomorphological characteristics of the study sites, namely the availability of displaceable sediments, the local topography and the tectonic influence such as crust uplift or crust subsidence. Tectonic uplift triggered by the AD 365 earthquake strongly affected the conservation potential of tsunami deposits especially because of intensified erosion that has affected uplifted coastal sections. In contrast, continuous Holocene subsidence of small geological basins along the north coast provided excellent fine-sedimentary traps. It was possible to reconstruct flow velocity patterns and flow dynamics associated with tsunami landfalls. For Sougia and Palaiochora, scenarios of tsunami wave propagation and landscape changes were presented. An issue still problematic is to obtain reliable age estimates of palaeotsunami events. First, material suitable for dating is not ubiquitous. Second, radiocarbon dating can be problematic because tsunamites usually also contain reworked material which renders sheer maximum ages. Third, using the sandwich dating approach, erosion effects or a post-sedimentary hiatus (for example by soil formation) are not considered. Our studies showed that best-fit age models are obtained by crosscheck-ing radiocarbon with OSL based ages and by comparing dating results from neighbouring geoarchives.
Publications
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2013. Reconstructing and modeling palaeotsunami events by multi-proxy geoscientific analyses. Reconstruction and Modeling of Palaeotsunami events: Multi-proxy Approaches, Geophysical Studies, Numerical Simulations. Eds.: Andreas Vött; Klaus Reicherter; loannis Papanikolaou. Zeitschrift für Geomorphologie, Supplementbände - Volume 57, 4: 1-4
Vött, A., Reicherter, K., Papanikolaou, I.
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2015. Planned palaeo-tsunami research in western Crete, Greece. In: Blumetti, A.M. et al. (eds) 2015. 27 Abstracts Volume 6th International INQUA Meeting on Palaeoseismology, Active Tectonics and Archaeoseismology. 19-24 April 2015, Pescina, Fucino Basin, Italy. ISSN: 2039-6651, 278-281
Mason, J., Schneiderwind, S., Mathes-Schmidt, M., Fischer, P., Werner, V., Vu, T., Papanikolaou, I., Vött, A., Reicherter, K.
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2015. Tsunamis as Palaeoseismic Indicators. Encyclopedia of Earthquake Engineering, Editors: Michael Beer, Ioannis A. Kougioumtzoglou, Edoardo Patelli, Ivan Siu-Kui Au; Spinger
Reicherter, K.
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2016. Geohazards: Coastal Disasters. Encyclopedia of Marine Geosciences. Springer, 276-283
Hoffmann, G., Reicherter, K.
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2016. Numerical Modelling of Tidal Notch Sequences on Rocky Coasts. Proceedings of the 7th International INQUA Meeting on Palaeoseismology, Active Tectonics and Archaeoseismology (J.P. McCalpin & C. Gruetzner, eds.). ISBN 978-0-9974355-2-8, 2016. Crestone Science Center, Crestone, CO 81131 USA, Guidebook No. 12; 7th International INQUA Meeting on Palaeoseismology, Active Tectonics and Archaeoseismology, Crestone (USA)
Schneiderwind, S., Kazmer, M., Boulton, S.J., Papanikolaou, I., Stewart, I., Reicherter, K.
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2016. The 365 AD tsunami imprint on the coasts of southwestern Crete - Sougia and Palaiochora case studies (Abstract). EGU General Assembly 2016, 17-22 April 2016, Vienna, Austria, p. 15679
Werner, V., Baika, K., Tzigounaki, A., Tsigkou, A., Fischer, P., Reicherter, K., Papanikolaou, I., Vött, A.
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2016. The geometry of tidal notches - What do they reveal about coastal tectonics? Proceedings of the 7th International INQUA Meeting on Palaeoseismology, Active Tectonics and Archaeoseismology (J.P. McCalpin & C. Gruetzner, eds.). ISBN 978-0-9974355-2-8, 2016. Crestone Science Center, Crestone, CO 81131 USA, Guidebook No. 12; 7th International INQUA Meeting on Palaeoseismology, Active Tectonics and Archaeoseismol-ogy, Crestone (USA)
Schneiderwind, S., Kazmer, M., Boulton, S.J., Papanikolaou, I., Stewart, I., Reicherter, K.
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2017. Innovative tidal notch detection using TLS and fuzzy logic: Implications for palaeo-shorelines from compres-sional (Crete) and extensional (Gulf of Cor inth) tectonic settings. Geomorphology 283, 189-200
Schneiderwind, S., Boulton, S.J., Papanikolaou, I.D., Reicherter, K.
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2017. Numerical modeling of tidal notch sequences on rocky coasts of the Mediterranean Basin. J. Geophys. Res. Earth Surf. 122
Schneiderwind, S., Boulton, S.J., Papanikolaou, I.D., Kazmer, M. Reicherter, K.
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2017. The sedimentary and geomorphological imprint of the AD 365 tsunami on the coasts of southwestern Crete (Greece) - Examples from Sougia and Palaiochora. In: Quaternary International
Werner, V., Baika, K., Fischer, P., Hadler, H., Obrocki, L., Willershäuser, T., Tzigounaki, A., Tsigkou, A., Reicherter, K., Papanikolaou, I., Emde, K., Vött, A.
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2017. The tsunami phenomenon. Progress in Oceanography 159, 296-322
Röbke, B.R., Vött, A.
