Browsing by Author "Szczuciński, W"
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- ItemApplications of geochemistry in tsunami research: a review(Elsevier, 2017-02-01) Chagué-Goff, C; Szczuciński, W; Shinozaki, TMuch progress has been made since the first published studies of tsunami deposits nearly 30 years ago. Geochemistry is now a much more widely used proxy in tsunami research, mainly due to its increasingly recognised value in the identification of historical and/or prehistorical deposits, at times even providing the conclusive proof when other proxies are missing or equivocal, but also its significance in environmental impact assessments following recent tsunamis. The rapid advance in analytical techniques has also made it a more approachable and popular method, as it is now often faster and cheaper. Here we provide a review of the applications of geochemistry, including the techniques used, as well as a database of studies that used chemical proxies in their investigation of recent and old events, including onshore and offshore tsunami deposits. Chemical signatures are often used as markers of marine inundation, either as salinity indicators, where they can also allow the identification of the limit of tsunami inundation, or tracers of the incorporation of marine-sourced carbonates. Their applications as indicators of source material are nevertheless expanding, thereby potentially providing additional information on the hydrodynamic processes associated with tsunami inundation, although they are largely site-specific. The effects of post-depositional changes in different climatic regimes are examined, with a particular emphasis on water-leachable components and implications for post-event recovery of coastal ecosystems. We demonstrate the usefulness of chemical proxies in studies of the geological record of tsunamis extending back thousands of years, suggest new approaches and discuss limitations and existing knowledge gaps. © 2016, Elsevier B.V.
- ItemEnvironmental impact assessment of the 2011 Tohoku-oki tsunami on the Sendai Plain(Elsevier B.V., 2012-12-30) Chagué-Goff, C; Niedzielski, P; Wong, HKY; Szczuciński, W; Sugawara, D; Goff, JRLarge areas of farmland in the Sendai Plain, Japan, were inundated by the 11 March 2011 Tohoku-oki tsunami and covered by a discontinuous 30–0.2 cm thick sediment layer consisting of sand and/or mud and generally thinning and fining inland. Two months after the tsunami, numerous rice paddy fields and depressions remained ponded with brackish or saline water. A series of field surveys in May, August and October 2011 were carried out north of Sendai airport, in order to assess the environmental impact of the tsunami. While evaporation had resulted in elevated conductivity in ponded water in May (up to 68.2 mS cm− 1), rainfall over the next five months led to dilution, although brackish water was still recorded in depressions and on paddy fields. Tsunami sediments, underlying soil and soil beyond the tsunami inundation limit were collected at 43 sites along and near a transect extending over 5 km inland, and analysed for grain size, organic content, water leachable ions, acid leachable metals and exchangeable metalloids. Water leachable anion and cation concentrations were elevated in sandy and muddy tsunami deposits and soils particularly in areas, where seawater had stagnated for a longer period of time after the tsunami, with up to 10.5% Cl, 6.6% Na, 2.8% SO4, 440 mg kg− 1 Br measured in surface sediments (< 0.5 cm depth). Vertical variations were also recorded, with higher concentrations often measured in the surface samples. A similar trend could be observed for some of the metalloids (As) and metals (Zn, Cu and Ni), although in general, maximum concentrations of metals and metalloids were not much higher than in soils not inundated by the tsunami and were within background levels for uncontaminated Japanese soils. The impact of saltwater inundation was documented in the chemistry of soils underlying tsunami sediments, which were affected by salt contamination down to ~ 15 cm depth, and soils not covered by tsunami deposits. The latter implies that the extent of tsunami inundation may successfully be determined using geochemical markers in absence of any sedimentological evidence. Water leachable ions mostly decreased over time, however, they remained high enough to impact on rice farming, which was completely halted in 2011. Although further work is required to assess the longer term impact of tsunami inundation, flushing of salt with freshwater, as well as the possible removal of sandy/muddy sediments and underlying soil are recommended to allow crop production to resume. © 2020 Elsevier B.V.
- ItemErosion, deposition and landscape change on the Sendai coastal plain, Japan, resulting from the March 11, 2011 Tohoku-oki tsunami(Elsevier B.V., 2020-12-12) Richmond, B; Szczuciński, W; Chagué-Goff, C; Goto, K; Sugawara, D; Witter, R; Tappin, DR; Jaffe, BE; Fujino, S; Nishimura, Y; Goff, JRCase studies of recent tsunami impacts have proven to be extremely useful in understanding the geologic processes involved during inundation and return flow, and refining the criteria used to identify paleotsunami deposits in the geologic record. Here, we report on erosion, deposition and associated landscape change resulting from the March 11, 2011 Tohoku-oki tsunami along a nearly 4.5 km shore-normal transect on the coastal plain near Sendai, Japan. The study area on the broad, low-relief prograding coastal Sendai plain comprised a sand beach backed by ~ 3 m high sand dunes and a forest, a wetland, the Teizan canal, agricultural rice fields, buildings and roads. Field observations focused on measurements of tsunami flow characteristics (height and direction), mapping of erosion features and assessing sediment deposition based on shallow trenches at 50–100 m spacing. Recorded tsunami inundation heights reached up to about 11 m above mean sea level within the first 500 m from the shoreline and then ranged between 3 and 5 m for the next 2 km, gradually decreasing to about 3 m close to the inundation limit. The tsunami deposit generally thinned landward from an average maximum ~ 30 cm thick sand deposit in the coastal forest to a thin mud drape several mm thick near the inundation limit. A discontinuous sand-dominated sheet was prevalent to about 2800 m from the shoreline where mud content then gradually increased further landward eventually resulting in a mud-dominated deposit ranging from 3.5 cm to a few mm thickness. The overall thinning and fining of the deposit was often interrupted by localized features that led to complex sedimentological relationships over short distances. Satellite imagery taken on 14 March 2011, 3 days after the Tohoku-oki Tsunami shows prominent foreshore incisions with 100 s + meters spacing alongshore, a foredune ridge that underwent severe erosion and development of a prominent shore-parallel elongated scour depression. Our field survey in early May 2011 revealed that the foreshore recovered quickly with rapid post-tsunami sediment deposition from incident waves, whereas the dune–ridge complex had undergone only minor re-working from eolian processes. © 2020 Elsevier B.V
- ItemField observations of erosion, deposition, and tsunami flow characteristics on the Sendai Coastal Plain after the March 2011, Tohoku-oki Tsunami, Japan(American Geophysical Union, 2011-11-05) Richmond, BM; Goto, K; Fujino, S; Nishimura, Y; Sugawara, D; Tappin, DR; Witter, RC; Jaffe, BE; Chagué-Goff, C; Szczuciński, W; Yulianto, E; Goff, JRHistorical and instrumental data show that the Pacific coast of Mexico has been exposed to destructive tsunamis over at least the past 500 years. This coast is also affected by hurricanes generated in the eastern Pacific. The great 1985 Mexico earthquake and its aftershock generated tsunamis that affected the Ixtapa-Zihuatanejo and Michoacán coast. The purpose of our study was two-fold, a) to determine whether we could distinguish storm from tsunami deposits, and b) whether tsunami deposits from historical events are preserved in the tropical environments of the Ixtapa-Zihuatanejo coast. Two anomalous sand units in the Ixtapa estuary are interpreted as the result of high-energy marine inundation events that occurred in the last century. Several lines of evidence using a multi-proxy approach (historical studies, interviews with local witnesses, geomorphological and geological surveys, coring and trenching, and laboratory analyses including grain size, micropaleontology, geochemistry, magnetic susceptibility and radiometric dating) indicate the occurrence of two tsunamis that we link to local events: the 1985 Mexico and possibly the 1979 Petatlan earthquakes. We thereby provide the first onshore geological evidence of historical tsunamis on the Pacific coast of Mexico. © American Geophysical Union
- ItemGeochemical mapping of tsunami inundation : beyond the sand(The Association of Applied Geochemists, 2013-11-17) Chagué-Goff, C; Wong, HKY; Goff, JR; Szczuciński, W; Gadd, PS; Cohen, DDTsunami deposits range from mud to boulders, depending upon the material available for transport by these devastating waves. As sandy beaches are most often eroded, many of the reported tsunami deposits are dominated by sand, and are identified in the geological record as an anomalous sand layer within a soil or peat profile, a bit like a layer cake. However, recent posttsunami surveys have shown that the sand layer may extend up to only 60‐70% of the tsunami inundation limit, and is thus not representative of the magnitude of the event. This invariably leads to underestimates of the size of the tsunami and the generating event. As shown by the 2011 Tohoku‐oki tsunami in Japan, this can have devastating outcomes. While the inundation limit can be mapped immediately after the event using the extent of debris, salt‐burned vegetation and water marks, this evidence is often lost over time and is therefore absent in the geological record. Here we report on two studies, where the tsunami inundation limit was mapped using geochemical methods. Six months after the 2010 Maulem Tsunami in Chile, the limit of inundation was identified based on chemical and microfossil data. In Japan, geochemical markers allowed the precise limit of inundation to be identified in the absence of any sedimentological evidence. Follow‐up studies also revealed that the marine geochemical signature was preferentially preserved in the mud component of the tsunami deposit which is found inland beyond the limit of sand deposition. As no marine microfossils were recovered in this area of Japan, geochemical mapping is proving to be the only means by which tsunami inundation maps can be redrawn allowing tsunami mitigation measures to be re‐assessed.
- ItemGeochemical signatures and source material of marine incursion deposits(Elsevier, 2016-01-01) Chagué-Goff, C; Andrew, AS; Szczuciński, W; Goff, JR; Nishimura, YThe geochemical signature of the Tohoku-oki tsunami deposit and underlying soil was assessed two months, five months and seven months after the 11 March 2011 tsunami inundated the Sendai Plain. The extent of the recognisable sand deposit was traced up to 2.9 km inland while a mud deposit was found up to 4.65 km inland, representing 60% and nearly 95% of the maximum tsunami inundation, respectively. The limit of tsunami inundation was identified 4.85 km from the shore using geochemical marine markers (S and Cl) two months after the tsunami, in the absence of any sedimentological evidence. Concentrations of other geochemical markers (K, Ca, Sr) indicative of the marine incursion and associated minerals were found to decrease landward. δ13C and δ15N and C/N ratios suggested a mixture of terrestrial and marine organic sources in the sediment, while δ34S of sulphate reflected the marine source of water soluble salts. The chemical composition of the 869 AD Jogan tsunami sand deposit was characterised by high Sr and Rb concentrations and was comparable to that of the Tohoku-oki tsunami deposit, suggesting that the sources of sediment may be similar. Marked decreases in S and Cl with time indicated that rainfall resulted in the leaching of salts from the sandy sediments. However, both S and Cl markers as well as Sr were still well preserved in the muddy sediments and underlying soil beyond the limit of the recognisable sand deposit seven months after the tsunami. This suggests that geochemical indicators may well be useful in identifying the extent of historical and palaeotsunamis by determining the marine origin of fine grained sediments beyond the limit of recognisable sand deposition, in particular when marine microfossils are sparse or lacking as is the case on the Sendai Plain. This would allow researchers to redraw palaeotsunami inundation maps and re-assess the magnitude of events such as the Jogan tsunami and other palaeotsunamis, not only on the Sendai Plain but also elsewhere around the world. This has important implications for tsunami risk assessment, hazard mitigation and preparedness.© 2012 Elsevier B.V.
- ItemGeochemical signatures up to the maximum inundation of the 2011 Tohoku-oki tsunami — Implications for the 869 AD Jogan and other palaeotsunamis(Elsevier B.V., 2012-12-30) Chagué-Goff, C; Andrew, AS; Szczuciński, W; Goff, JR; Nishimura, YThe geochemical signature of the Tohoku-oki tsunami deposit and underlying soil was assessed two months, five months and seven months after the 11 March 2011 tsunami inundated the Sendai Plain. The extent of the recognisable sand deposit was traced up to 2.9 km inland while a mud deposit was found up to 4.65 km inland, representing 60% and nearly 95% of the maximum tsunami inundation, respectively. The limit of tsunami inundation was identified 4.85 km from the shore using geochemical marine markers (S and Cl) two months after the tsunami, in the absence of any sedimentological evidence. Concentrations of other geochemical markers (K, Ca, Sr) indicative of the marine incursion and associated minerals were found to decrease landward. δ13C and δ15N and C/N ratios suggested a mixture of terrestrial and marine organic sources in the sediment, while δ34S of sulphate reflected the marine source of water soluble salts. The chemical composition of the 869 AD Jogan tsunami sand deposit was characterised by high Sr and Rb concentrations and was comparable to that of the Tohoku-oki tsunami deposit, suggesting that the sources of sediment may be similar. Marked decreases in S and Cl with time indicated that rainfall resulted in the leaching of salts from the sandy sediments. However, both S and Cl markers as well as Sr were still well preserved in the muddy sediments and underlying soil beyond the limit of the recognisable sand deposit seven months after the tsunami. This suggests that geochemical indicators may well be useful in identifying the extent of historical and palaeotsunamis by determining the marine origin of fine grained sediments beyond the limit of recognisable sand deposition, in particular when marine microfossils are sparse or lacking as is the case on the Sendai Plain. This would allow researchers to redraw palaeotsunami inundation maps and re-assess the magnitude of events such as the Jogan tsunami and other palaeotsunamis, not only on the Sendai Plain but also elsewhere around the world. This has important implications for tsunami risk assessment, hazard mitigation and preparedness. © 2020 Elsevier B.V.
- ItemGeological and geochemical field survey on the Sendai Plain following the 11 March 2011 Tohoku-Oki Tsunami(American Geophysical Union, 2011-12-05) Chagué-Goff, C; Goto, K; Fujino, S; Nishimura, D; Szczuciński, W; Rishmond, B; Tappin, D; Jaffe, BE; Witter, R; Yulianto, K; Goff, JRA post-tsunami survey was carried out in May 2011 by members of a UNESCO-IOC International Tsunami Survey Team. The geological and geochemical survey was carried out along a transect extending 4.5 km inland north of Sendai airport, and focused on tsunami flow characteristics, sedimentation and erosion, as well as assessing the impact of saltwater contamination on the paddy fields . Tsunami inundation in this area reached c. 4.5 km inland, and the limit was marked by the elevated Tobu Highway, except where underpass structures allowed inundation further inland. The tsunami deposit generally thinned and fined inland, with the sandy deposit thinning landward from about 30 cm thickness in the coastal forest to less than 0.5 cm c. 2.8 km inland. Rip-up clasts were observed mostly near the base of the sandy deposits. Further inland, the deposit was dominated by mud, although it contained thin sand laminae one to a few grain-thick up to the limit of inundation near Tobu Highway. The thickness of the tsunami deposit was found to show large variability over short distances. Erosion and liquefaction features were also commonly observed. Ponded water was reported between the coastal forest and up to 2.6 km inland, while salt crusts were observed on numerous rice paddy fields up to the limit of tsunami inundation, where the water had evaporated. Conductivity measurements of ponded water, canals, irrigation and drainage channels revealed that the water was still saline to brackish, despite >60 mm of precipitation in the two months since the tsunami. Elevated concentrations of water-leachable chloride (salt) were measured both in mud and sand deposits, where seawater had stagnated and evaporated.
- ItemHeavy minerals in the 2011 Tohoku-oki tsunami deposits—insights into sediment sources and hydrodynamics(Elsevier B.V., 2012-12-30) Jagodziński, R; Sternal, B; Szczuciński, W; Chagué-Goff, C; Sugawara, DThe 2011 Tohoku-oki tsunami left sand and mud deposits more than 4 km inland on the coastal plain of Sendai, Japan. The tsunami deposits, pre-tsunami soils and beach sediments were analysed for grain size, and heavy mineral content and assemblages to test the applicability of heavy mineral analyses in the identification of tsunami deposits and interpretation of associated sedimentation processes. Heavy minerals comprised on average 35% of the tsunami deposit in the 0.125–0.25 mm grain size fraction. The most common were orthopyroxenes, clinopyroxenes, amphiboles, limonites and opaque minerals. Heavy mineral concentrations and assemblages were similar in the tsunami deposits, beach and pre-tsunami soils and sediments and thus tsunami deposits could not simply be identified based on their heavy minerals. Sediment provenance analysis revealed that tsunami deposits left within 1.5 km of the shoreline were mostly eroded from the beach, dune and local soils, while deposits farther inland (> 1.5 km) were mostly derived from local soil erosion. No evidence was found for a significant contribution of offshore sediments. Detailed analyses revealed that the lowermost portion of tsunami deposits was mostly of local origin, while the sediment source of the upper portion was variable. A comparison with a previous study of heavy minerals in 2004 IOT deposits confirms that heavy minerals in tsunami deposits are mostly source-dependent and may represent a useful supplementary tool in studies of tsunami deposits. However, the interpretation must always be placed in the local geological context and corroborated with other “tsunami proxies”. © 2020 Elsevier B.V.
- ItemImpact of tsunami inundation on soil salinsaltion - up to one year after the 2011 Tohoku-okitsunami(Springer, 2013-09-27) Chagué-Goff, C; Wong, HKY; Sugawara, D; Goff, JR; Nishimura, Y; Beer, J; Szczuciński, W; Goto, KThe long-term effect of tsunami inundation on soil salinisation was assessed following the 2011 Tohoku-oki tsunami in two areas on the Sendai Plain, near Sendai airport in the Miyagi Prefecture and Matsukawa-ura near Soma in the Fukushima Prefecture. Data gathered over four sampling seasons 2, 5, 9 and 11 months after the tsunami near Sendai airport show that the salt content generally decreased with time. Concentrations were nevertheless higher in February 2012 than in October 2011, probably due to capillary action and evaporation following long periods with little precipitation in the winter, while the lower concentrations in October were attributed to dilution due to intense rainfall prior to the sampling period. In February 2012, the area with chloride concentrations over the guidelines for the establishment of rice seedlings still extended for nearly 1 km between 2.45 and 3.33 km inland. Chloride concentrations also reached the guideline values at the land surface 1.71 km inland. This corresponded to the limit of the area deemed not suitable for rice production by local rice farmers. However, recent observations revealed that rice crops were not only halted in 2011 but also in 2012, probably due to high salinisation of soil and/or surface and groundwater. Our study shows that soil salinisation was still recorded to nearly 15 cm depth in areas with fine-grained organic-rich soil ~2.5 km from the shoreline 11 months after the tsunami, and that water-leachable ions were preferentially retained in organic-rich muddy sediment and soil, reflecting the long-term impact of tsunami inundation. In Matsukawa-ura, salt crusts still covered the area flooded by the tsunami in February 2012 and both the soil and muddy tsunami deposit were characterised by high chloride and sulphate concentrations. The latter might also lead to sulphide toxicity. Remediation measures have been implemented in certain areas, but further research needs to be carried out to test the effectiveness of the measures being used to allow rice production to resume. © 2014, Springer Science+Business Media Dordrecht.
- ItemInitial field survey report of the 2011 East Japan Tsunami in Sendai, Natori adn Iwanuma Cities(UNESCO-IOC, 2011-07-10) Sugawara, D; Goto, K; Chagué-Goff, C; Fujino, S; Goff, JR; Jaffe, BE; Nishimura, Y; Richmond, B; Szczuciński, W; Tappin, DR; Witter, R; Yuliento, EThe East Japan Earthquake (Mw 9.0) and associated tsunami struck the Pacific coast of eastern Japan on March 11th, 2011 at 2:46 p.m. (Japan Standard Time). Maximum run-up heights reached about 40 m along the Sanriku region’s coast and around 10 m on the Sendai coastline. The coasts of Iwate, Miyagi and Fukushima Prefectures in particular were badly damaged, and a considerable amount of time and money will be required to restore these areas. Tsunami inundation up to 5 km inland occurred across the Sendai Plain, which remained partly flooded for several weeks after the event. Some areas were still under water 2 months after the earthquake, and are likely to remain flooded for some time as a result of subsidence. The Disaster Control Research Center at Tohoku University conducted scientific research of the inundated coastal plains of Sendai, Natori and Iwanuma Cities in collaboration with other research institutes from Japan and overseas with the support of UNESCO-IOC (Intergovernmental Oceanographic Commission). Data and samples collected during the field survey are now being analyzed by various institutes around the World. This report is a summary of our field survey that focused on an area to the north of Sendai Airport. Radioactivity data recorded at the time of survey are also provided.
- ItemModern and possible paleotsunami deposits in Samenoura, Sanriku Coast, and their relation to tsunami source mechanisms(Japan Geoscience Union Meeting, 2014-05-02) Sugawara, D; Nishimura, Y; Goto, K; Goff, JR; Jaffe, BE; Richmond, B; Chagué-Goff, C; Szczuciński, W; Yokoyama, Y; Miyairi, Y; Sawada, CSamenoura is situated in the bay head of a small inlet on the Pacific coast of Oshika Peninsula, one of the nearest places to the epicenter of the 2011 Tohoku-oki Earthquake. According to the Joint Survey Group, wave heights were measured at more than 20 m near the coastline. This area was severely damaged as a result of both co-seismic subsidence and tsunami inundation. We carried out field surveys of the Tohoku-oki and paleotsunami deposits at Samenoura in March, May and October 2013. Sandy deposits laid down by the Tohoku-oki tsunami were up to 20 cm thick at locations with an elevation greater than 10 m, and were several cm thick within the forest higher up. The tsunami deposit also contained numerous shell fragments and foraminifera. Although some possible sources of the tsunami deposits can be attributed to narrow sandy beaches near the study area, the deposition of such a thick sandy deposit is more or less enigmatic, considering the steep Ria-type coastal topography.Using a gouge auger and geoslicer, we found at least two sand layers intercalated within muddy sediments. A volcanic ash layer, which corresponds to the AD 915 Towada-a tephra, was also identified from a horizon between these sand layers. The underlying sand layer was most probably laid down by the 869 Jogan earthquake tsunami, one of the large-scale events known to have affected the region. Previous studies of the Jogan tsunami have proposed several possible source models that involve an interplate thrust earthquake. Given that the local bathymetry and topography of Samenoura Bay may be sensitive to the waveform of a large-scale tsunami, paleotsunami deposits found from this area may be the key to determining the source mechanisms of events on the Sanriku Coast.In this presentation, the possible correlation of the sandy deposits with known paleotsunami events based on detailed radiocarbon dating is discussed. The hydrodynamic character and processes of tsunami sediment erosion and deposition in Samenoura Bay are analyzed using numerical modeling of both interplate and outer-rise earthquake scenarios. © Japan Geoscience Union Meeting, 2014.
- ItemNew insights of tsunami hazard from the 2011 Tohoku-oki event(Elsevier, 2011-12-01) Goto, K; Chagué-Goff, C; Fujino, S; Goff, JR; Jaffe, BE; Nishimura, Y; Richmond, B; Sugawara, D; Szczuciński, W; Tappin, DR; Witter, R; Yulianto, EWe report initial results from our recent field survey documenting the inundation and resultant deposits of the 2011 Tohoku-oki tsunami from Sendai Plain, Japan. The tsunami inundated up to 4.5 km inland but the >0.5 cm-thick sand deposit extended only 2.8 km (62% of the inundation distance). The deposit however continued as a mud layer to the inundation limit. The mud deposit contained high concentrations of water-leachable chloride and we conclude that geochemical markers and microfossil data may prove to be useful in identifying the maximum inundation limit of paleotsunamis that could extend well beyond any preserved sand layer. Our newly acquired data on the 2011 event suggest that previous estimates of paleotsunamis (e.g. 869 AD Jogan earthquake and tsunami) in this area have probably been underestimated. If the 2011 and 869 AD events are indeed comparable, the risk from these natural hazards in Japan is much greater than previously recognized. (c) 2011 Elsevier
- ItemSediment sources and sedimentation processes of 2011 Tohoku-oki tsunami deposits on the Sendai Plain, Japan — insights from diatoms, nannoliths and grain size distribution(Elsevier B.V., 2012-12-30) Szczuciński, W; Kokociński, M; Chagué-Goff, C; Cachão, M; Goto, K; Sugawara, DThe 11th March 2011 Tohoku-oki tsunami inundated the low-lying Sendai Plain (Japan) more than 5 km inland leaving sand and mud deposits over most of the area. In order to establish the sources of the tsunami deposits and interpret processes of their sedimentation, samples were collected from the deposits, underlying soils and the beach along a shore-perpendicular transect and analysed for grain size, diatom assemblages and nannoliths. The fining-inland tsunami deposits consisted of poorly to moderately sorted medium to coarse sand within 2 km of the coastline and very poorly to poorly sorted mud farther inland. More specifically, there was a slight fining of the coarse to medium sand mode within the sandy deposits and an increased contribution of the coarse and very coarse silt fraction in the mud deposits. The tsunami deposits also exhibited vertical changes including fining upward and coupled coarsening-fining upward trends. Few diatoms were present in beach sediments, soils and tsunami deposits within 1 km of the coastline, while diatoms were more abundant farther inland. Diatom assemblages in the soil and tsunami deposits were similar and dominated by species typical of freshwater-brackish habitats, while no typically marine species were encountered. Nannoliths were generally absent in the studied sediments, except for few specimens. Our data indicate that there was probably no or only a very minor component of marine sediments transported onland by the tsunami. The sandy tsunami deposits within ~ 1 km of the coastline were mostly derived from beach and dune erosion. From 1 to 2 km landward the contribution of these sources decreased, while sources comprising local soil erosion and the entrainment of sediments from the Teizan-bori canal increased. Farther inland, local soil erosion was the major sediment source for the mud deposits. The tsunami deposits were most likely deposited during at least two inundations, mostly out from suspension resulting in an upward grain size fining trend. However, bed load deposition was also important in the sandy deposits as suggested by a common grain size upward coarsening, position on C–M diagrams and frequent horizontal lamination. The present study reveals that even very large tsunamis may not transport marine sediments onland and thus many commonly applied indicators of tsunami deposits based on the assumption of their offshore origin (marine diatoms, foraminifera, nannoliths, marine sediments) may be of limited use. © 2020 Elsevier B.V.