Tsunami hazard assessment in the Ionian Sea due to potential tsunamogenic sources – results from numerical simulations

Tselentis, G‐Akis; Stavrakakis, G.; Sokos, Efthimios; Gkika, F.; Serpetsidaki, A.

doi:10.5194/nhess-10-1021-2010

Cited by 14 publications

(9 citation statements)

References 30 publications

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“…In the last decade, several studies have been made in western Greece in order to reconstruct the Holocene coastal and environmental changes (Kontopoulos and Avramidis, ; Kraft et al ., ; Poulos et al ., ; Kelletat, ; Cundy et al ., ; Vött, ; Avramidis et al ., ; Scheffers et al ., ; Vött et al ., ; Avramidis and Kontopoulos, ; Kontopoulos and Koutsios, ). Coastal and lagoon sedimentation in western Greece has regularly been influenced by Holocene tsunami inundations (Kontopoulos and Avramidis, ; Scheffers et al ., ; Vött et al ., ), while a resent tsunami hazard assessment for the Ionian Sea has been proposed by Tselentis et al ., ().…”

Section: Geological and Tectonic Settingmentioning

confidence: 99%

Geochemical processes and sedimentological characteristics of Holocene lagoon deposits, Alikes Lagoon, Zakynthos Island, western Greece

Panagiotaras¹,

Papoulis

Κοντόπουλος

et al. 2012

Geological Journal

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In this paper we present sedimentological, geochemical, mineralogical and 14 C Accelerator Mass Spectrometry (AMS) dating data of a 21.0-m core obtained from Alikes Lagoon, Zakynthos Island. It is the first time that sedimentological and geochemical data are presented, up to 21-m depth, from an Holocene coastal lagoon environment of the Ionia Sea, western Greece. The sedimentological properties and the geochemical composition of sediments were studied for the time period between 8540 years BP to present. Samples were analysed for their particle size, calcium carbonate and total organic carbon (TOC) content. Moreover, bulk sample chemical analyses for major and trace elements were carried out, as well as bulk, oriented mineralogical analyses for the clay fraction (<2 mm) were determined by powder X-Ray diffraction. The grain size characteristics, statistical parameters and TOC, for the Holocene analysed samples, suggest a coastal environment (restricted-shallow) with reduced salinity such as a tidal flat and/or particularly marsh in a lagoon margin. Sediment characteristics as well as trace element records may contain additional new palaeoclimate information that provide important new constraint on sediment depositional environment and Holocene climate. Stratigraphic variation of geochemical indices, such as Rb/Ti, Cs/Ti, Eu/Eu*, Th/Ti, La/Ti, Ta/Ti, Yb/Ti and Y/Ti, for the sediments with ages from 8540 to 7210 years BP, remain relatively constant indicating that the provenance of the Alikes Lagoon remained similar throughout the mid Holocene. However, geochemical indices in sediments with ages from 7110 years BP to present, indicate the transition from a warm and wet climate in the middle Holocene to a relatively cold climatic conditions in modern times.

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Section: Geological and Tectonic Settingmentioning

confidence: 99%

Geochemical processes and sedimentological characteristics of Holocene lagoon deposits, Alikes Lagoon, Zakynthos Island, western Greece

Panagiotaras¹,

Papoulis

Κοντόπουλος

et al. 2012

Geological Journal

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“…Minimum wave heights calculated for boulder dislocation at the study sites, correspond to results reported from south‐eastern Sicily (Scicchitano et al ., ; Barbano et al ., ) and from southern Apulia (Mastronuzzi et al ., ). Numerical simulations of tsunami wave propagation in the Gulf of Kyparissia, underline the possibility of tsunami wave heights high enough to initiate boulder movement (Tselentis et al ., ; Röbke et al ., ).…”

Section: Discussionmentioning

confidence: 96%

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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“…Besides tsunamis caused by local offshore faults or submarine slides, potential impact of teletsunamis have to be considered for the western Peloponnese, such as the AD 365 event triggered by an earthquake that took place offshore western Crete (Papadopoulos et al, 2014a). Moreover, the coastline of the Gulf of Kyparissia is directly exposed to the Hellenic Trench which is located only 70 to 80 km offshore (Papanikolaou et al, 2007), and to the Filiatra and Zakynthos faults (Tselentis et al, 2010). Moreover, due to its position southward of the protecting Ionian Islands, the gulf is open towards the central Ionian Sea.…”

Section: Introductionmentioning

confidence: 99%

Tracing tsunami signatures of the ad 551 and ad 1303 tsunamis at the Gulf of Kyparissia (Peloponnese, Greece) using direct push in situ sensing techniques combined with geophysical studies

et al. 2019

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The western Peloponnese was repeatedly hit by major tsunami impacts during historical times as reported by historical accounts and recorded in earthquake and tsunami catalogues. Geological signatures of past tsunami impacts have also been found in many coastal geological archives. During the past years, abundant geomorphological and sedimentary evidence of repeated Holocene tsunami landfall was found between Cape Katakolo and the city of Kyparissia. Moreover, neotectonic studies revealed strong crust uplift along regional faults with amounts of uplift between 13 m and 30 m since the mid‐Holocene. This study focuses on the potential of direct push in situ sensing techniques to detect tsunami sediments along the Gulf of Kyparissia. Direct push measurements were conducted on the landward shores of the Kaiafa Lagoon and the former Mouria Lagoon from which sedimentary and microfaunal evidence for tsunami landfall are already known. Direct push methods helped to decipher in situ high‐resolution stratigraphic records of allochthonous sand sheets that are used to document different kinds of sedimentological and geomorphological characteristics of high‐energy inundation, such as abrupt increases in grain size, integration of muddy rip‐up clasts and fining upward sequences which are representative of different tsunami inundation pulses. These investigations were completed by sediment coring as a base for local calibration of geophysical direct push parameters. Surface‐based electrical resistivity tomography and seismic data with highly resolved vertical direct push datasets and sediment core data were all coupled in order to improve the quality of the geophysical models. Details of this methodological approach, new in palaeotsunami research, are presented and discussed, especially with respect to the question of how the obtained results may help to facilitate tracing tsunami signatures in the sedimentary record and deciphering geomorphological characteristics of past tsunami inundation. Using direct push techniques and based on sedimentary data, sedimentary signatures of two young tsunami impacts that hit the Kaiafa Lagoon were detected. Radiocarbon age control allowed the identification of these tsunami layers as candidates for the ad 551 and ad 1303 earthquake and tsunami events. For these events, there is reliable historical data on major damage on infrastructure in western Greece and on the Peloponnese. At the former Mouria Lagoon, corroborating tsunami traces were found; however, in this case it is difficult to decide whether these signatures were caused by the ad 551 or the ad 1303 event.

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Tsunami hazard assessment in the Ionian Sea due to potential tsunamogenic sources – results from numerical simulations

Cited by 14 publications

References 30 publications

Geochemical processes and sedimentological characteristics of Holocene lagoon deposits, Alikes Lagoon, Zakynthos Island, western Greece

Geochemical processes and sedimentological characteristics of Holocene lagoon deposits, Alikes Lagoon, Zakynthos Island, western Greece

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

Tracing tsunami signatures of the ad 551 and ad 1303 tsunamis at the Gulf of Kyparissia (Peloponnese, Greece) using direct push in situ sensing techniques combined with geophysical studies

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