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Exploring the potential of Lake Hamana (Shizuoka Prefecture, Japan) to hold a long and reliable sedimentary record of paleo-earthquakes and -tsunami along the Nankai-Suruga Trough.
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Coastal Lake Hamana is located near the convergent tectonic boundary of the Nankai-Suruga Trough, along which the Philippine Sea slab subducts underneath the Eurasian Plate, giving rise to repeated tsunamigenic megathrust earthquakes (Mw≥8). A good understanding of the earthquake- and tsunami-triggering mechanisms in terms of rupture mode and recurrence pattern in time and space, is crucial in order to better estimate the complexity of seismic risks for the densely populated Enshu-nada coast. Based on existing historical data of paleoseismicity (last ~1300 years), the easternmost segment (Tōkai segment) of the Nankai-Suruga Trough appears to exhibit a seismic gap and is expected to rupture in the near future, causing the next “Tōkai earthquake”. Studying the sedimentary infill of Lake Hamana may help to fine-tune hazard assessment in the area of interest. Thanks to its extensive accommodation space, the Hamana lake basin is considered to be a good archive of past “big wave” events. Fieldwork (Oct.-Nov. 2014) comprised a reflection-seismic survey for imaging the lake’s stratigraphic features, based on which favourable locations for gravity coring were selected. A systematic sampling of bottom sediments from different sites enables us to evaluate vertical as well as lateral changes in depositional environment, including event deposits generated by tsunamis and tropical storms (i.e. typhoons). An important part of the study is dedicated to qualitatively distinguish sedimentary facies of storm deposits from the ones generated by tsunamis, since this is an essential step in correctly assessing future hazards. For identification of marine tsunami incursions, a set of sedimentological, geophysical, geochemical and micropaleontological analyses are applied on the core sediments in a multi-proxy approach. Radionuclide dating provides the necessary timeframe and information on prevailing sedimentation rates. Sites bearing the potential of recording complete and long event histories will be sampled with long cores.
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No RBINS Staff publications
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On how to extract the paleotsunami history from a coastal lake record
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Coastal lake records can be successfully used for reconstructing continuous histories of tsunamigenic megathrust earthquakes. Here, we apply a wide range of methods on one Japanese and two Chilean coastal lakes and show that the selection of coring locations benefits significantly from accompanying geophysical survey data. High-resolution seismic profiles display several strong reflectors in all three lake basins, allowing us to map the depth and extent of coarse-grained tsunami deposits. Side scan sonar imagery enables us to reconstruct past tsunami inundation pathways.
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No RBINS Staff publications
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The QuakeRecNankai project: Palaeoseismic data for improved seismic hazard assessment along the Nankai Trough, Japan
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No RBINS Staff publications
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New Geological Evidence of Past Earthquakes and Tsunami Along the Nankai Trough, Japan
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The east coast of Japan is prone to tsunamigenic megathrust earthquakes, as tragically demonstrated in 2011 by the Tōhoku earthquake (Mw 9.0) and tsunami. The Nankai Trough subduction zone, to the southwest of the area affected by the Tōhoku disaster and facing the densely populated and heavily industrialized southern coastline of central and west Japan, is expected to generate another megathrust earthquake and tsunami in the near future. This subduction zone is, however, segmented and appears to be characterized by a variable rupture mode, involving single- as well as multi-segment ruptures, which has immediate implications for their tsunamigenic potential, and also renders the collection of sufficiently long time records of past earthquakes and tsunami in this region fundamental for an adequate hazard and risk assessment. Over the past three decades, Japanese researchers have acquired a large amount of geological evidence of past earthquakes and tsunami, in many cases extending back in time for several thousands of years. This evidence includes uplifted marine terraces, turbidites, liquefaction features, subsided marshes and tsunami deposits in coastal lakes and lowlands. Despite these efforts, current understanding of the behaviour of the subduction zone still remains limited, due to site-specific evidence creation and preservation thresholds and issues over alternative hypotheses for proposed palaeoseismic evidence and insufficiently precise chronological control. Within the QuakeRecNankai project we are generating a long and coherent time series of megathrust earthquake and tsunami recurrences along the Nankai Trough subduction zone by integrating all existing evidence with new geological records of paleo-tsunami in the Lake Hamana region and of paleo-earthquakes from selected lakes in the Mount Fuji area. We combine extensive fieldwork in coastal plain areas and lakes, with advanced sedimentological and geochemical analyses and innovative dating techniques.
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No RBINS Staff publications
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Een GIS benadering van de bronstijdgrafheuvel in Zandig-Vlaanderen : enkele voorlopige resultaten (België)
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No RBINS Staff publications
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The timing of aeolian events near archaeological settlements around Heidebos (Moervaart area, N Belgium)
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No RBINS Staff publications
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Seafloor morphology and habitats of tidal channels in the Venice Lagoon, Italy tidal channel habitats. Chapter 9.
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RBINS Staff Publications 2020
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Limitations of Predicting Substrate Classes on a Sedimentary Complex but Morphologically Simple Seabed
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RBINS Staff Publications 2020
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Ergasilid copepods in Africa: first application of next-generation sequencing and update on distribution and phylogenetic position of Ergasilus kandti, a parasite of cichlid fishes
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Ergasilidae are a family of globally distributed copepods parasitizing freshwater fishes. Despite their widespread occurrence, their phylogeographic patterns are poorly understood, specifically in the African Great Lakes. Here, we aim to provide an update on distribution of Ergasilus kandti, a copepod species infecting Tylochromis polylepis, an endemic cichlid fish species in Lake Tanganyika, and the phylogenetic relationship of African ergasilids. We present the first record of E. kandti parasitizing the gills of T. polylepis in Lake Tanganyika proper, identified through light microscopy and, for the first time for any ergasilid, confocal laser scanning microscopy. We suggest that this technique adds spatial context to characters and are hardly visible while using light microscopy. Phylogenetic analyses based on ribosomal DNA fragments suggest two monophyletic groups of African ergasilids. However, the phylogenetic relationships of Ergasilus remain unresolved, possibly because of the insufficient resolution of these widely used phylogenetic markers and low taxonomic coverage. A comparison of ergasilid mitochondrial genomes highlights traits found in other parasite lineages including genome shrinkage and low evolutionary rates of the cox1 gene. This study presents the most extensive molecular characterization of any ergasilid species to date.
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RBINS Staff Publications 2024
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Recent non-marine ostracods (Crustacea) from New Caledonia (Melanesia, Pacific Ocean)
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The New Caledonian Archipelago is a hot spot for biodiversity and endemism. Here, we report on new records of nine species from localities on the main island, Grande Terre, and illustrate these: Ilyodromus viridulus (Brady, 1886), Stenocypris hislopi Ferguson, 1969, S. macedonica Petkovski & Meisch, 1996¸ S. malayica Victor & Fernando, 1981, Bradleytriebella lineata (Victor & Fernando, 1981), Hemicypris pyxidata (Moniez, 1892), Heterocypris incongruens (Ramdohr, 1808), Cypridopis vidua (O.F. Müller, 1776) and Limnocythere stationis Vávra, 1891. We also provide redescriptions and illustrations of the valves and carapace of Stenocypris marginata Daday, 1910 sensu Méhes, 1939, Cypris granulata Daday, 1898 and Kennethia major (Méhes, 1939); for the latter species also including some soft parts. Therefore, twenty two certain species have thus far been reported from the New Caledonian Archipelago. The status of seven uncertain species is also discussed. Previous records of Stenocypris major (Baird, 1859) from Grande Terre, mainly by Méhes, are here considered to belong to S. hislopi. We propose to reject the presence of Cyprinotus cingalensis Brady, 1886 in New Caledonia and suggest to consider Cypridopsis sarasini Méhes, 1939 as an “uncertain species” (sensu Meisch et al. 2019). We also argue that Eucypris wolffhuegeli Méhes, 1914 might be a synonym of H. incongruens and suggest that Strandesia rouxi Méhes, 1939 might be considered a junior synonym of an existing species, pending further research.
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RBINS Staff Publications 2024