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Geological evidence for historical and older earthquakes and tsunamis along the Nankai Trough, Japan
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In the wake of the devastating 2011 Tōhoku earthquake and tsunami, the Central Disaster Management Council of the Japanese Cabinet Office issued new guidance for assessing seismic hazards in Japan. Before 2011, seismic hazard assessment relied on source models developed from knowledge of a small number of well-documented historical earthquakes. Less well-known historical earthquakes, including the AD 869 Jōgan Sanriku earthquake, were largely disregarded as their seismic intensities or tsunami heights could not be reconciled with the chosen seismic sources. Following the unexpectedly large size of the Tōhoku earthquake, the Cabinet Office advocated renewed investigation of earthquake and tsunami occurrence over historical and longer timescales, with a particular focus on defining the largest possible magnitudes. The new guidelines pay close attention to the Nankai Trough, the subduction zone where the Philippine Sea Plate dives beneath the Eurasian Plate. The Nankai Trough faces the densely populated and highly industrialised coastline of south central Japan and harbours a widely-known seismic gap along its eastern Tōkai segment. A full-length rupture of the Nankai Trough, including the Tōkai segment, could produce an earthquake with a magnitude approaching that of the 2011 event, with tsunami travel times to the closest shorelines of less than 30 minutes. We review geological evidence for historical and older earthquakes and tsunamis along the Nankai Trough. This evidence comes from a wide variety of sources, including uplifted marine terraces, subsided marshes, liquefaction features, turbidites and tsunami deposits in coastal lakes and lowlands. Examining papers published before and after 2011, we investigate the impact of the new Cabinet Office guidelines on attempts to understand the magnitude and recurrence of these events. Additionally, we introduce the Belgian Science Policy Office funded QuakeRecNankai project, a collaboration aiming to supplement existing records by generating a long time series of earthquake and tsunami recurrence from sites at the eastern end of the Nankai Trough. The project uses a diverse range of geophysical, sedimentological, geochemical and microfossil approaches to investigate records of Holocene paleotsunamis in and around Lake Hamana and records of seismic shaking from the Fuji Five Lakes.
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No RBINS Staff publications
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Geological evidence for Holocene earthquakes and tsunamis along the Nankai-Suruga Trough, Japan
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RBINS Staff Publications 2016
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Geological provenance of the Nehalennia votive altars from Colijnsplaat (province of Zeeland, The Netherlands): preliminary results
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RBINS Staff Publications 2016
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Geological record and sedimentology of the Palaeozoic oolitic ironstone deposits in Western Europe. Spatial relationships with the Linienbandkeramik settlements (LBK) in Belgium.
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RBINS Staff Publications
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Geological resource management of the future : Drilling down the possibilities. Poster presentation 2nd Deep Water Circulation Congress : The contourite Log-book, Gent, Belgium, 10 - 12/09/2014.
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RBINS Staff Publications
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Géométrie et morphométrie des côtes : de Kebara 2 à l’humain moderne
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Introduction Les côtes sont des os plats dotés d’une corticale fine rendant ces structures fragiles. En archéologie, les vestiges costaux retrouvés sont ainsi souvent des fragments plutôt que des côtes complètes. Quelques rares échantillons de Néandertaliens sont disponibles, cependant une exception existe, le squelette de Kebara 2 [1] comportant l’ensemble des côtes ainsi que la majorité des éléments vertébraux. Cette étude apporte un complément à l’analyse des paramètres géométriques et morphométriques des côtes de l’humain moderne et de Kebara 2. Méthode Une procédure de calcul automatisée a été développée afin de pouvoir extraire les caractéristiques géométriques et morphométriques tridimensionnelles des côtes à partir d’acquisitions tomodensitométriques et de reconstructions obtenues après segmentation. Divers paramètres tels, la longueur de l’arc costal, longueur de la corde, la plus grande largeur, la surface de section le long du corps, la circonférence, les courbures de torsion, d’enroulement et selon les bords ont été mesurés sur les reconstructions 3D de Kebara 2 [2] ainsi que sur un échantillon de 14 sujets humains modernes (adultes sains, 7 hommes/7 femmes) pour les étages costaux 1 à 9. Résultats L’ensemble des paramètres mesurés et notamment l’angle de torsion ou la courbure selon les bords sont sujets à une variabilité importante chez l’humain moderne. Les résultats obtenus à partir des reconstructions des côtes de Kebara 2 sont similaires à ceux mesurés chez les humains modernes pour la majorité des paramètres. Conclusion Cette étude contribue au débat concernant les dimensions thoraciques des Néandertaliens et leurs plausibles implications physiologiques [3]. Plusieurs travaux ont statué en faveur d’une différence majeure entre le thorax de Néandertalien et l’humain moderne. Malgré quelques variations aux étages inférieurs, les résultats de cette étude semblent démontrer que la géométrie et morphométrie des côtes reconstruites de Kebara 2 se situe dans les limites de l’humain moderne.
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RBINS Staff Publications
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Geomorphological mapping of the Belgian seabed and its submerged landscapes
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Low- and high-resolution Digital Terrain Models (DTMs) are available as interoperable gridded data layers and data products. These bathymetry data, together with increasing availability of various terrain analysis tools, give new impetus to a more uniform geomorphological mapping of the marine realm. To test approaches in sandy shelf areas, a multi-scale analysis was already performed on bathymetric data from the Belgian part of the North Sea using the Benthic Terrain Modeler (BTM) in ArcGIS and other GIS-related raster tools for analysing the topography of the seabed. Geomorphological features present on the Belgian Continental Shelf are sandbanks and crests, valleys and depressions, and sandwave fields. Recently, a derivative of the digital bathymetry model was constructed based on in-depth processing and re-interpretations of sediment cores in conjunction with extensive seismic records, resulting in a depth-converted structure map (DCSM) of the Top-Paleogene surface at high-resolution scale of 1:250 000 (De Clercq et al., 2016). Similar GIS analyses have now been conducted on the appearing submerged landscapes from 120,000 to 100,000 years ago allowing revealing planation surfaces, escarpements, slope breaks, paleo-valleys and -ridges in an automated way. Both resulting geomorphological mapping products contribute to EMODnet-Geology’s work packages on geomorphology and submerged landscapes. De Clercq, M., Chademenos, V., Van Lancker, V., & Missiaen, T. (2016). A high-resolution DEM for the Top-Palaeogene surface of the Belgian Continental Shelf. Journal of Maps 12(5), 1047-1054.
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RBINS Staff Publications 2019
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Geophysical investigations to evaluate the potential of DGE in Wallonia
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RBINS Staff Publications 2023
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Geophysical well log correlations in the Quaternary deposits of the Campine area, northern Belgium
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RBINS Staff Publications 2021
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Geothermal Energy potential in Wallonia
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RBINS Staff Publications 2023
