Tsunami Deposits

espanolLos reservorios de gas somero en los sedimentos marinos del margen iberico o sus escapes se pueden detectar por metodos directos mediante: (1) la medicion de concentraciones elevadas de metano u otros hidrocarburos en la columna de agua o en testigos de sedimentos, (2) la identificacion en el fondo marino de comunidades quimiosinteticas y/o de carbonatos autigenicos y (3) la identificacion (mediante videos submarinos) de crateres (pockmarks) o monticulos de carbonatos y volcanes de fango asociados al escape de fluidos; o por tecnicas indirectas mediante la caracterizacion de anomalias en registros acusticos tales como: (1) la presencia de plumas acusticas en los registros de ecosonda, (2) la identificacion de apantallamientos y/o turbidez acusticos en los registros sismicos de alta resolucion, (3) la interpretacion de reflectividades y (4) de morfologias de crateres o montes submarinos en los registros de sonar de barrido lateral y ecosondas multihaz. En este articulo se pres...

Arctic regions are warming faster than the global average, leading to significant changes in permafrost, vegetation dynamics, and soil nutrient availability. Understanding these interactions is essential for predicting the rapidly changing behavior of tundra ecosystems. In central Spitsbergen, we examined the growth of Salix polaris across various elevations to assess the impact of local habitat conditions and climate change. The results obtained indicate heterogeneous growth of this species. Dendrochronological analyses revealed that low-elevation valley-bottom sites showed a strong positive correlation between June temperatures and ring growth (r = 0.69), supported by high soil moisture (up to 70 %) and nutrient-rich soils. These areas exhibited higher productivity, referred to as 'greening,' with Normalized Difference Vegetation Index (NDVI) values reaching approximately 0.5. However, increased rain-on-snow (ROS) events and rapid soil drainage caused a late summer drought. In contrast, higher elevations experienced delayed yet sustained growth in mid-to-late summer, supported by permafrost moisture retention despite colder early summers. NDVI values at high elevations ranged from 0.0 to 0.15, with soil moisture peaking around 40 %. The varied growth responses underscore the necessity of integrating multiple factors, such as soil chemistry, geomorphology, moisture variability, high-resolution imagery, and dendroclimatology, into predictive models. Relying solely on summer warmth is insufficient for understanding the complex growth behaviors in high-Arctic regions. Comprehensive approaches are necessary to accurately forecast future vegetation shifts and their ecological impacts in the High Arctic.

The Doñana National Park is a Biosphere Reserve located within the estuary of the Guadalquivir River (SW Spain). It is mainly composed of extensive fluvio-tidal marshes partially protected by an elongated sandy spit. Three phases have been distinguished in the late Holocene evolution of this spit based on textural, geochemical, palaeontological and, chronological data recorded in a long core (31 m). Phase 1 (890 BCE-218 BCE) is characterized by the alternation of lagoonal silty sediments and slightly polluted marsh deposits, the latter with contamination from thousand-year-old mining. Phase 2 (218 BCE-90 CE) is characterized by several historical tsunamis, which caused the erosion of previous dune systems and the deposit of these sandy sediments on the adjacent bottom of the lagoon. Phase 3 (90 CE-Present) includes a regressive sequence (lagoonal bottommarsh-dune system), with the pollution of lagoonal sediments due to Roman mining activities.

DESCRIPTION This paper presents the preliminary results of a multidisciplinary study of the mixed wave-and-tide dominated estuary of the Piedras River in the mesotidal coast of the Gulf of Cadix. Nineteen hand cores and three mechanical drill cores allowed reconstructing the history of infill. Overlying the erosional surface incising the Mio-pliocene pre-estuarine deposits there follows a succession of fluvio-marine deposits (ca. 9000 calBP), an open estuarine facies with central basin muds and sandy tidal delta interbeds, with a maximum ca. 6.500 calBP, and a transition to tidal flat deposits after ca. 2800 calBP. Two episodes of extreme wave energy at ca. 3000 calBP and ca. 195 calBP were identified and interpreted as tsunami surges, the latter ascribed to the catastrophic Lisbon earthquake and the related tsunami.

Tsunami deposits have been widely studied in temperate latitudes, but the intrinsic difficulties associated with tropical coastal environments, and the intensity of bioturbation in these habitats, limit the possibilities of analysing these formations. Here, we investigate the deposits on the Colima coast of Mexico, which overlies the subducting Rivera and Cocos Plates, in order to reconstruct the tsunami inundation history and related hazard. We developed a multi-proxy study aimed to recognize and date historical and palaeotsunami deposits, including historical data on the effects of a known tsunami, geomorphological mapping, stratigraphic, grain size, organic matter content, diatoms, geochemical composition, magnetic susceptibility, and anisotropy of magnetic susceptibility, together with radiometric dating ( 210 Pb and 14 C). We identified two probable tsunami deposits at Palo Verde estuary including a historical event associated with the Mw 6.9 earthquake on 22 June 1932 and a palaeotsunami most likely generated by a similar event in the fourteenth century. This work shows that it is possible to identify both historical and palaeotsunamis in the tropical environment of Mexico's Pacific coast. These data will serve to enhance our understanding of tsunami deposits in tropical environments and of the regional tsunami hazard.

The September 29th 2009 tsunami caused widespread coastal modification within the islands of Samoa and northern Tonga in the South Pacific. Preliminary measurements indicate maximum runup values of around 17 m and shore-normal inundation distances of up to ~620 m . Geological field reconnaissance studies were conducted as part of an UNESCO-IOC International Tsunami Survey Team survey within three weeks of the event in order to document the erosion, transport, and deposition of sediment by the tsunami. Data collected included: a) general morphology and geological characteristics of the coast, b) evidence of tsunami flow (inundation, flow depth and direction, wave height and runup), c) surficial and subsurface sediment samples including deposit thickness and extent, d) topographic mapping, and e) boulder size and location measurements. Four main types of sedimentary deposits were identified: a) gravel fields consisting mostly of isolated cobbles and boulders, b) sand sheets from a few to ~25 cm thick, c) piles of organic (mostly vegetation) and man-made material forming debris ramparts, and d) surface mud deposits that settled from suspension from standing water in the tsunami aftermath. Tsunami deposits within the reef system were not widespread, however, surficial changes to the reefs were observed.

The stratigraphy within coastal river valleys in south-central Chile clarifies and extends the region’s history of large, earthquakes and accompanying tsunamis. Our site at Quidico (38.1°S, 73.3°W) is located in an overlap zone between ruptures of magnitude 8–9 earthquakes in 1960 and 2010, and, therefore, records tsunamis originating from subduction-zone ruptures north and south of the city of Concepción. Hand-dug pits and cores in a 3-m-thick sequence of freshwater peat in an abandoned meander (a little-examined depositional environment for tsunami deposits) and exposures along the Quidico River show five sand beds that extend as much as 1.2 km inland. Evidence for deposition of the beds by tsunamis includes tabular sand beds that are laterally extensive (>100 m), well sorted, fine upward, have sharp lower contacts, and contain diatom assemblages dominated by brackish and marine taxa. Using eyewitness accounts of tsunami inundation,137Cs analyses, and14C dating, we matched the ...

The Doñana National Park is a Biosphere Reserve located within the estuary of the Guadalquivir River (SW Spain). It is mainly composed of extensive fluvio-tidal marshes partially protected by an elongated sandy spit. Three phases have been distinguished in the late Holocene evolution of this spit based on textural, geochemical, palaeontological and, chronological data recorded in a long core (31 m). Phase 1 (890 BCE-218 BCE) is characterized by the alternation of lagoonal silty sediments and slightly polluted marsh deposits, the latter with contamination from thousand-year-old mining. Phase 2 (218 BCE-90 CE) is characterized by several historical tsunamis, which caused the erosion of previous dune systems and the deposit of these sandy sediments on the adjacent bottom of the lagoon. Phase 3 (90 CE-Present) includes a regressive sequence (lagoonal bottommarsh-dune system), with the pollution of lagoonal sediments due to Roman mining activities.

DESCRIPTION This paper presents the preliminary results of a multidisciplinary study of the mixed wave-and-tide dominated estuary of the Piedras River in the mesotidal coast of the Gulf of Cadix. Nineteen hand cores and three mechanical drill cores allowed reconstructing the history of infill. Overlying the erosional surface incising the Mio-pliocene pre-estuarine deposits there follows a succession of fluvio-marine deposits (ca. 9000 calBP), an open estuarine facies with central basin muds and sandy tidal delta interbeds, with a maximum ca. 6.500 calBP, and a transition to tidal flat deposits after ca. 2800 calBP. Two episodes of extreme wave energy at ca. 3000 calBP and ca. 195 calBP were identified and interpreted as tsunami surges, the latter ascribed to the catastrophic Lisbon earthquake and the related tsunami.

The Doñana National Park is a Biosphere Reserve located within the estuary of the Guadalquivir River (SW Spain). It is mainly composed of extensive fluvio-tidal marshes partially protected by an elongated sandy spit. Three phases have been distinguished in the late Holocene evolution of this spit based on textural, geochemical, palaeontological and, chronological data recorded in a long core (31 m). Phase 1 (890 BCE-218 BCE) is characterized by the alternation of lagoonal silty sediments and slightly polluted marsh deposits, the latter with contamination from thousand-year-old mining. Phase 2 (218 BCE-90 CE) is characterized by several historical tsunamis, which caused the erosion of previous dune systems and the deposit of these sandy sediments on the adjacent bottom of the lagoon. Phase 3 (90 CE-Present) includes a regressive sequence (lagoonal bottommarsh-dune system), with the pollution of lagoonal sediments due to Roman mining activities.

West Australian coastlines experienced several tsunamis in mid-Holocene times. To expand our knowledge about Holocene tsunami events in West Australia, the authors extended the previously studied spatial scale to include the central-and southwestern coastlines. Several of the discovered events were mid-and young Holocene (≤1000 yr BP) tsunami impacts on the outer coast of the Cape Range Peninsula. Five hundred kilometres to the south between Cape Cuvier and Point Quobba, additional tsunami evidence exists on top of steep cliffs over a coastal stretch of 30 km. The sedimentary signature of two tsunamis is documented in this area by wide ridges comprised of sand, shell, and clasts (including coral fragments) at heights of 12-30 m asl and 300-500 m inland. Enigmatic boulders (20-100 tons) appear as cliff-top megaclasts up to 100 m inland. Here, radiocarbon dating revealed a minimum of two tsunami events: at 5700 yr BP with waves depositing sandy ridges far inland and at approximately 1000 yr BP with waves depositing boulders originating from the marine environment. As the first dates are congruent with previously published results for the Learmonth region 500 km to the north, we assume that the same mid-Holocene tsunami hits this long coastal section as well. The southwestern coast of West Australia from Cape Naturaliste to Albany also shows signs of impacts by extreme waves. Here, huge granite boulders (80-400 tons) were dislocated and transported to heights up to 10 m above sea level. The most prominent dislocated boulders were positioned at Merchant Rock (Cape Naturaliste National Park), at Islet near Nanarup, and in Cave Bay close to Albany.

I, Megan Gomes, declare that this thesis is my own, unaided work, except where referenced and otherwise acknowledged. This thesis is submitted in fulfilment of the requirements for the degree of Master of Science at the University of the Witwatersrand, Johannesburg. I have not submitted this work for examination at any other university.

The stratigraphy within coastal river valleys in south-central Chile clarifies and extends the region’s history of large, earthquakes and accompanying tsunamis. Our site at Quidico (38.1°S, 73.3°W) is located in an overlap zone between ruptures of magnitude 8–9 earthquakes in 1960 and 2010, and, therefore, records tsunamis originating from subduction-zone ruptures north and south of the city of Concepción. Hand-dug pits and cores in a 3-m-thick sequence of freshwater peat in an abandoned meander (a little-examined depositional environment for tsunami deposits) and exposures along the Quidico River show five sand beds that extend as much as 1.2 km inland. Evidence for deposition of the beds by tsunamis includes tabular sand beds that are laterally extensive (>100 m), well sorted, fine upward, have sharp lower contacts, and contain diatom assemblages dominated by brackish and marine taxa. Using eyewitness accounts of tsunami inundation,137Cs analyses, and14C dating, we matched the ...

The objective of this work was to contribute to the knowledge of microphytobenthos in the Adriatic Sea, by studying for the first time the benthic diatom communities in Neum Bay in Bosnia and Herzegovina. For this purpose, the benthic diatoms naturally growing on stones and macroalgae were identified at one station in the small semi-enclosed oligotrophic Neum Bay during 2010 and 2011. A total of 24 samples were collected at two different depths, 0.5 m and 8 m, and analysed with light and scanning electron microscopy. Altogether, 425 pennate and 58 centric taxa (species and infraspecific taxa) belonging to 60 families and 115 genera were noted. Genera with the greatest number of taxa were: Mastogloia (46 taxa), Navicula (36), Diploneis (35), Nitzschia (34), Amphora (31), Cocconeis (27), Achnanthes (14), Halamphora (12), Lyrella (11), and Surirella and Licmophora (10 each). Amphora bigibba var. interrupta and Cocconeis scutellum were the most frequent taxa, being present in 87.5% of the samples. In total, 142 taxa were found only once (sporadic taxa). Although benthic diatom richness is high in the bay, taxa are apparently not distributed evenly temporally. Consistent quantitative and qualitative data are still needed for a better determination of the seasonal and spatial changes of the epilithic assemblages in the region.

The stratigraphy within coastal river valleys in south-central Chile clarifies and extends the region’s history of large, earthquakes and accompanying tsunamis. Our site at Quidico (38.1°S, 73.3°W) is located in an overlap zone between ruptures of magnitude 8–9 earthquakes in 1960 and 2010, and, therefore, records tsunamis originating from subduction-zone ruptures north and south of the city of Concepción. Hand-dug pits and cores in a 3-m-thick sequence of freshwater peat in an abandoned meander (a little-examined depositional environment for tsunami deposits) and exposures along the Quidico River show five sand beds that extend as much as 1.2 km inland. Evidence for deposition of the beds by tsunamis includes tabular sand beds that are laterally extensive (>100 m), well sorted, fine upward, have sharp lower contacts, and contain diatom assemblages dominated by brackish and marine taxa. Using eyewitness accounts of tsunami inundation,137Cs analyses, and14C dating, we matched the ...

Taphonomic process of diatom valves was investigated with samples from a surface sediment core and a sediment trap above it in Omura Bay, western Japan. Extremely weak diatom valves of a coastal marine diatom, Chaetoceros affinis Lauder was considerably observed in the sediment core, whereas the other Chaetoceros species with weak valves like C. affinis rarely occurred even though they were found in trap samples. Biweekly sediment trap experiments revealed the season when each Chaetoceros species bloomed and deposited on seafloor. The observation suggests that the latest bloomed Chaetoceros valves (younger than 7-8 months) were preserved in the sediments. Vertical mixing of loose sediments by seawater movement and burrowing invertebrates seems to work within the depth of 5 cm of surface deposits according to observation of sedimentary structures and stratigraphical distribution of C, affinis in the core. The diatom valves are well mixed in this layer within 4 weeks.

1.はじめに 中米・エルサルバドル共和国の南部海岸低地には、レンパ川河口付近 から東にのびる沿岸砂州(サン・フアン・デル・ゴソ半島:長さ約 34km) とこれに大部分を閉塞されたラグーン(ヒキリスコ潟)がみられる。現 在、ラグーン内は魚貝に富み、マングローブ林が分布することから、ヒ キリスコ潟北岸地域や潟内の小島に多数見られる先スペイン期の生活趾 も、こうした水産資源や森林資源を背景に成立していた可能性が指摘さ れている。しかしながら、この地域にみられる生活趾は、先古典期(B.C. 2000~A.D.250)~古典期前期(A.D.250~600頃)のものがほとんどで、 古典期後期(A.D.600頃~900)以降のものはほとんどない。また、現在 の沿岸砂州(サン・フアン・デル・ゴソ半島)には、遺跡が見いだされ ていないが、近年、本地域に分布するイロパンゴ火山 3~6世紀巨大噴火 による降下テフラ(TBJテフラ)と地形発達との関係から、現在の沿岸 砂州は噴火後に形成され、噴火以前は潟内の小島列の付近に砂州があっ たことが明らかになってきた(北村,2016)。噴火の前後で、ラグーンの 状況が変化したことにより、ラグーン内のマングローブ林も何らかの影 響を受けて変化した可能性があるが、マングローブ林の変遷については、 これまで明らかにされてこなかった。 そこで、本研究では、ラグーン内に分布するマングローブ林下の有機 質泥質堆積物をハンドオーガーにより採取し、複数の層隼の放射性炭素 年代測定の結果から、マングローブ林の形成や衰退・拡大の変遷につい て考察する。 2.マングローブ林下の有機質泥質堆積物と年代 1)ラグーン北岸地域3地点と南岸地域3地点で、ハンドオーガーによ りマングローブ林下の堆積物を採取した。 2)有機質泥質堆積物は、1.3~2.5m程度の厚さで、その下位には砂層 が見られる。また、北岸では、有機質泥質堆積物に砂泥層が挟在する。 3)北岸のコアからは、深さ 1.1~1.4m付近、砂泥層の下端にTBJテフ ラの火山ガラスに富む層隼が見いだされた。また、2地点において、火 山ガラスに富む層隼の直上に 10~20cmの厚さの砂泥質で偽層などを挟 む再堆積層が見いだされ、さらにその上位に有機質泥質堆積物の堆積が みられた。 4)南岸のコアからは、砂泥層および T...

Identification of past tsunamis is important for risk assessment and management of coastal areas. Obtaining accurate and precise ages of sediments originating from such extreme marine coastal floods is crucial for a reliable estimation of the recurrence interval of these often devastating events. We present here the results of quartz optical dating and 14 C dating of two sites (Boca do Rio and Martinhal) on the Algarve coast (southern Portugal). These sites contain deposits of the great tsunami of November 1, 1755. The sections were described using sedimentological techniques; at both sites tsunami-laid sands and gravels were identified, intercalated between estuarine muds. Quartz luminescence ages from these sedimentary successions were derived using standard SAR-OSL dating using multi-grain sub-samples. A multiple sampling strategy was employed with several samples taken from the AD 1755 tsunami deposit and from the sediments bracketing the tsunami layer. Our SAR-OSL protocol was shown to be appropriate using dose recovery measurements (measured/given dose ratio of 1.004 AE 0.007, n ¼ 165). The several OSL ages from the 1755 tsunamigenic deposits are internally reproducible but yield age overestimates of between 20 and 125% (60-310 years respectively); this is in agreement with values reported in the literature for similar deposits. The age overestimation of the tsunami-laid sands is presumably due to the rapid erosion and deposition of older sediments, with insufficient light exposure for complete bleaching during the tsunami event itself. The absence of significant bleaching during the tsunami is also suggested by the shape of the dose distributions based on sub-samples made up of only about 100 grains. Analysis of the distributions with the minimum-age model seems to yield the expected age for two of the three distributions. It is important to note that age offsets of a few tens of years to a few hundred years rapidly become insignificant when dating older (>1 to few ka) tsunami layers.

A reconnaissance was conducted in Thailand to investigate the effects of the 26 December 2004 tsunami on buildings, bridges, and other physical infrastructure. It was observed that nonengineered reinforced concrete buildings, low-rise timber frames, and unreinforced masonry walls suffered extensive damage from hydrodynamic pressures generated by the tsunami. A large number of nonengineered reinforced concrete frame buildings experienced partial or total collapse, while well-designed engineered structures survived the tsunami with little or no damage. Specific observations made during the reconnaissance indicate the engineering significance of the disaster.

The stratigraphy of the Bahía Inglesa Formation in the Caldera Basin west of Copiapó, (north-central Chile) is revised, based on hitherto unpublished stratigraphic sections and 87 Sr/ 86 Sr dating. The depositional environment varied from a rocky shoreline to the upper continental slope, with sea-level oscillations and tectonic movements causing numerous local unconformities as well as lateral and vertical facies changes. Geohistory and sedimentological analyses show that the area was close to the concurrent sea level at about 15.3 Ma, but at the same time being elevated about 100 m above the present sea level. Although the basin then subsided at least 350 m until around 6 Ma, marine deposition was only recorded after 10.4 Ma. This suggests that the sea level initially dropped faster than the rate of subsidence so that subaerial erosion occurred. The period of subaerial exposure before 10.4 Ma can be attributed to the presence of a NE-trending branch of the Juan Fernández Ridge below the continental crust at this time, whereas the ensuing subsidence was due to subduction erosion and crustal accommodation in its wake as it migrated south along the South American coastline. The subsequent uplift of at least 250 m can be explained by an acceleration in plate expansion and isostatic rebound of the continental crust after being partially submerged in the upper mantle. The uplift-subsidence-uplift pattern mirrors those recorded around the Nazca Ridge in Peru, as well as in similar basins to the south of Caldera. However, a higher southward migration rate of the Juan Fernández Ridge against the edge of the South American Plate and less intense upliftsubsidence-uplift cycles are recorded in the latter basins. This can possibly be attributed to oroclinal bending of the ridge due to friction with the overlying continental plate, which diminished the angle of incidence and the intensity of the stress field, but increased the migration velocity of the ridge relative to the coastline.

Bangka Island has primary and secondary tin deposit. However, along the history of tin mining has been done the primary tin deposit domination is less than secondary tin deposit. Secondary tin deposit is formed from Granitic S-type source rock weathering and then transported by gravity. After that, Cassiterite mineral (SnO 2) accumulates and forms a placer deposit in the study area. The thickness of sediment cover at Toboali Waters is quite diverse, with a range between 5-20 milliseconds, by knowing the quarter sediment thickness using seismic data interpretation results, is expected to give an idea about tin placer deposit potential in Toboali waters. Based on the Isochron map shows patterns of quaternary sediment thickening to the southwest, south and southeast of Bangka Island.

The multidisciplinary study of Gunung Padang has revealed compelling evidence of a complex and sophisticated megalithic site. Correlations between rock stratifications observed through surface exposures, trenching and core logs, combined with GPR facies, ERT layers, and seismic tomograms, demonstrate the presence of multi-layer

The multidisciplinary study of Gunung Padang has revealed compelling evidence of a complex and sophisticated megalithic site. Correlations between rock stratifications observed through surface exposures, trenching and core logs, combined with GPR facies, ERT layers, and seismic tomograms, demonstrate the presence of multi-layer constructions spanning approximately 20-30 m. Notably, a high-resistive anomaly in electric resistivity tomography aligns with a low-velocity anomaly detected in seismic tomography, indicating the existence of hidden cavities or chambers within the site. Additionally, drilling operations revealed significant water loss, further supporting the presence of underground spaces. Radiocarbon dating of organic soils from the structures uncovered multiple construction stages dating back thousands of years BCE, with the initial phase dating to the Palaeolithic era. These findings offer valuable insights into the construction history of Gunung Padang, shedding light on the engineering capabilities of ancient civilizations during the Palaeolithic era.

Two types of handcorers with different internal diameters (MBARI type corer [MC] ; 7cm, KITAZATO type corer [KC] ; 8cm) were evaluated for their sampling efficiency and sampler bias on meiofauna, based on the samples collected with these corers during dives #820 ~ 822 of ROV "Hyper Dolphin" at Myojin Knoll, which is about 150km south-southwest of Hachijo Island. It was suggested that the sampling efficiency became worse when overlying water above sediment is leaked from the core samples, regardless of corer type. Meiofauna in the sediments collected with KC showed the "general" vertical distribution pattern; meiofauna were concentrated in the surface layer of the sediments. On the other hand, in the sediments collected with MC, the vertical profiles of meiofauna were rather "uniform". Furthermore, the community compositions at higher taxonomic level were different from those in the sediments collected with KC. These differences between the corers would be attributed to the differences in core diameter and the degree of disturbance to the edge and surface of the sediment samples. Handcorer-sampling with ROVs or submersibles is essential to the studies on meiofauna around hydrothermal vents. These results of this study, however, suggest that comparing meiofaunal data based on samples collected with different types of handcorers should be done carefully.

We examined time and spatial distributions of sedimentary facies surrounding the spit sediments in the bay-mouth portion of the Paleo-Okutokyo Bay by using sedimentary facies and radiocarbon dates obtained from two sediment cores (MZ and SZ cores) from the eastern margin of the Tokyo Lowland. Latest Pleistocene to Holocene incised-valley fills (the Chuseki-so) which unconformably overlie Middle to Late Pleistocene deposits (Shimosa Group) consist of braided river, meandering river, estuary, spit and delta sediments in MZ core in ascending order. The Chuseki-so consists of delta sediments in SZ core. MZ and SZ cores yields radiocarbon dates ranging from 13150 to 3160 cal BP and from 3930 to 730 cal BP, respectively. Sand shoal sediments constituting part of the spit sediments in MZ core forms a sand body which elongates northeastward from the spit sediments. And this sand body seems to have deposited in a bay-mouth channel which existed behind the spit between 4500 and 3500 cal BP.

Chuseki-so", which is an incised-valley fill deposited since the last glacial maximum, is distributed under the Nakagawa Lowland, Saitama Prefecture, central Japan. In this study, sedimentary facies, radiocarbon dates and sediment properties of the GS-SK-1 cores (GS-SK-1A, GS-SK-1N and GS-SK-1T) drilled at a central part of the Nakagawa Lowland, were analyzed for clarifying stratigraphy and sedimentary environments of incised valley fills in the Nakagawa Lowland. The "Chusekiso" of the GS-SK-1A core is composed of fluvial to shallow marine sediments as follows, in ascending order: (1) fluvial channel fills of pebble to pebbly sand, (2) flood plain to salt marsh deposits of alternation of sand and mud, (3) muddy tidal flat deposits of massive mud containing molluskan fossils, (4) sandy tidal flat to sand shoal deposits of poorly-sorted silty sand containing shell fragments and granules, (5) inner bay (prodelta to delta front) deposits of massive mud intercalated by thin ripple sand and abundant burrows, and (6) fluvial channels fills to flood plain deposits of alternation of sand and mud. Nineteen radiocarbon dates, 48,350 to 1,270 yrBP in radiometric 14 C ages, indicate that the incised valley fills are formed by a set of transgression and regression. Sediment properties, i.e. N-value, mud contents, bulk densities, magnetic susceptibility, water contents, luminosity and color contrasts of these deposits, vary stratigaraphically, corresponding to sedimentary facies or at boundaries of them.

We test the application of dendrochronological methods for dating and assessing the environmental impacts of tsunamis in polar regions, using an example of the 21 Novem− ber 2000 landslide−generated tsunami in Vaigat Strait (Sullorsuaq Strait), West Greenland. The studied tsunami inundated a c. 130 m−wide coastal plain with seawater, caused erosion of beaches and top soil and covered the area with an up to 35 cm−thick layer of tsunami de− posits composed of sand and gravel. Samples of living shrub, Salix glauca (greyleaf wil− low) were collected in 2012 from tsunami−flooded and non−flooded sites. The tree−ring analyses reveal unambiguously that the tsunami−impacted area was immediately colonized during the following summer by rapidly growing shrubs, whilst one of our control site spec− imens records evidence for damage that dates to the time of the tsunami. This demonstrates the potential for dendrochronological methods to act as a precise tool for the dating of Arc− tic paleotsunam...

Our study presents the results of determining labile aluminium form in samples from the 2004 tsunamiaffected coastal zone of Thailand. The samples were collected from tsunami deposits, beach sediments, sediments underlying the tsunami deposits (pre 2004 tsunami soil), as well as from soils from areas, that were not flooded. The extraction of the labile form of aluminium was performed using 3 mol L-1 HCl in twelve grain size fractions. In the surface layer samples the highest concentrations were determined in the tsunami deposits in fractions <0.063 mm (5850 mg kg-1). The highest determined concentration in the whole set of investigated samples occurred in soil sample in fractions 0.09-0.125 mm (19770 mg kg-1). An increase in concentration of labile aluminium form, along with decreasing grain diameter, was observed in samples from all the studied settings. In general, concentrations were higher in soil samples not affected by the tsunami. This is probably due to steady weathering of minerals during soil forming processes and removal of sediment grain surface coatings potentially enriched in labile Al during high energy transport by tsunami.

The Indian Ocean tsunami flooded the coastal zone of the Andaman Sea and left tsunami deposits with a thickness of a few millimetres to tens of centimetres over a roughly one-kilometre-wide tsunami inundation zone. The preservation potential and the post-depositional changes of the onshore tsunami deposits in the coastal plain setting, under conditions of a tropical climate with high seasonal rainfall, were assessed by reinvestigating trenches located along 13 shore-perpendicular transects; the trenches were documented shortly after the tsunami and after 1, 2, 3 and 4 years. The tsunami deposits were found preserved after 4 years at only half of the studied sites. In about 30% of the sites, the tsunami deposits were not preserved due to human activity; in a further 20% of the sites, the thin tsunami deposits were eroded or not recognised due to new soil formation. The most significant changes took place during the first rainy season when the relief of the tsunami deposits was levelled; moderate sediment redeposition took place, and fine surface sediments were washed away, which frequently left a residual layer of coarse sand and gravel. The fast recovery of new plant cover stabilised the tsunami deposits and protected them against further remobilisation during the subsequent years. After five rainy seasons, tsunami deposits with a thickness of at least a few centimetres were relatively well preserved; however, their internal structures were often significantly blurred by roots and animal bioturbation. Moreover, soil formation within the deposits caused alterations, and in the case of thin layers, it was not possible to recognise them anymore. Tsunami boulders were only slightly weathered but not moved. Among the various factors influencing the preservation potential, the thickness of the original tsunami deposits is the most important. A comparison between the first post-tsunami survey and the preserved record suggests that tsunamis with a run-up smaller than three metres are not likely to be preserved; for larger tsunamis, only about 50% of their inundation area is likely to be presented by the preserved extent of the tsunami deposits. Any modelling of paleotsunamis from their deposits must take into account post-depositional changes.

The 2004 tsunami deposits and probable paleotsunami deposits were studied at the southern Kho Khao Island, on Andaman Sea coast of Thailand. The 2004 tsunami laid down about 8 cm of fining upward medium sand and locally about 40 cm of massive coarse sand with common mud clasts. The sediments were characterized by the presence of marine foraminiferal assemblage; however, already after 5 years many of carbonate foraminiferal tests were partly or completely dissolved. The probable paleotsunami deposits form layer about 1 m thick. It consists of massive very coarse sand with common big shells and mud clasts. Its composition suggests a marine origin and the presence of mud clasts, and similarity to the 2004 tsunami deposits suggests that the layer was left by paleotsunami, which took place probably during the late Holocene, even though two shells within the layer gave 14 C ages of 40,000 years or more.

The tsunami deposits left by the 26 December 2004 tsunami in the coastal zone of Thailand were studied within two months of the event and before any significant postdepositional changes could occur. The sediment structure and texture (grain size), as well as its thickness and spatial distribution, were documented for the tsunami deposits in 12 shore-perpendicular transects from areas of various tsunami runup and wave heights. The tsunami deposits were as thick as 0.4 m and were located as far as 1.5 km inland. They were composed mostly of poorly sorted sand and often consisted of one to four normally graded, massive or laminated layers. The deposits generally became finer in the landward direction; however, landward thinning trend of the deposits is not clear, and the maximum accumulation often is not located close to the shoreline but rather is further inland. In comparable coastal environments with similar available sediment sources the tsunami size (represented as the tsunami runup height) is reflected in the resulting deposits. Larger tsunamis are associated with deposits that are thicker, have a maximum accumulation located farther inland, include a finer sediment fraction (likely from deeper offshore areas) and frequently are composed of normally graded layers.

Introduction on the 26 th of December 2004 at 00:58:53 universal time (u.T.) an earthquake of surface wave magnitude (M s) 9.0 occurred off the west coast of northern Sumatra (Fig. 1). The recorded magnitude was second only to the 1960 Chilean earthquake [1]. The earthquake generated large tsunamis that severely damaged coastal communities in countries around the indian ocean, including indonesia, Thailand, Sri Lanka and india. The waves were recorded around the world [2]. The documented death toll exceeded 283,000, with the heaviest loss along the west coast of Sumatra, where more than 1 million people were displaced. Damage to houses, infrastructure and livelihoods

Taphonomic process of diatom valves was investigated with samples from a surface sediment core and a sediment trap above it in Omura Bay, western Japan. Extremely weak diatom valves of a coastal marine diatom, Chaetoceros affinis Lauder was considerably observed in the sediment core, whereas the other Chaetoceros species with weak valves like C. affinis rarely occurred even though they were found in trap samples. Biweekly sediment trap experiments revealed the season when each Chaetoceros species bloomed and deposited on seafloor. The observation suggests that the latest bloomed Chaetoceros valves (younger than 7-8 months) were preserved in the sediments. Vertical mixing of loose sediments by seawater movement and burrowing invertebrates seems to work within the depth of 5 cm of surface deposits according to observation of sedimentary structures and stratigraphical distribution of C, affinis in the core. The diatom valves are well mixed in this layer within 4 weeks.

Sedimentological study was carried out in order to clarify the paleotsunami history in the northern Hokuriku region. Facies analysis for short core samples collected from the lowland behind a beach ridge in Shimao, Himi city, Toyama prefecture determine that the lowland beds consist of sediments from a beach ridge, a marsh, a pond and a swamp, and identify six event deposits in these sediments. Two of these event deposits or wood fragments rich layers were found in the almost same depth below the ground level, setting these two event deposits as an event bed. The observed 14 C age below this event bed is 2,344-2,155 cal BP. The mineralogical and sedimentological characteristics as well as spatial distribution of the observed event bed suggest that it may have been originated from a tsunami. However, the possibility of a river flooding event cannot be excluded, and therefore further study is needed to clarify the origin of it.

An appropriate foreshore management should take into account coastal processes based on physical and biological features of the particular coastal environment. This study aims to determine the coastal landform and its instability and susceptibility through satellite study, thematic map, and groundtruth checking. The coastal landform of Pati is typified by the muddy coast with ~1 km tidal mudflat moving seaward and coastal plain moving landward. Mangrove ecosystem, mainly Avicennia, intermittently occurs along the coast of Pati resting on muddy substrates where tributaries drain off water from the hinterland. The coastal plain is largely occupied by salt and/or fish ponds. Considering the geological condition, coastal characteristic, and oceanographic processes, the coast of Pati has medium to high-risk level of landform changes with shoreline changes greater than 1 m/yr and 5 to 10 yearly coastal inundation driven by the erosion and sedimentation. The study provides insight in recog...

The multidisciplinary study of Gunung Padang has revealed compelling evidence of a complex and sophisticated megalithic site. Correlations between rock stratifications observed through surface exposures, trenching and core logs, combined with GPR facies, ERT layers, and seismic tomograms, demonstrate the presence of multi-layer

Change of structure community of Macrozoobenthos due to sedimentation has apparently contributed to a reduction of the quality of the aquatic environment, particularly in Segara Anakan Lagoon. This study aims to determine the extent to which the effects of sedimentation and nutrients in the Segara Anakan Lagoon on macrozoobenthos community structure. The method used in this study surveys. Primary data collected are nutrients, macrozoobenthos, sedimentation rate and secondary data. The results showed that the rate of sedimentation in the dry and rainy season was 0.067 to 2 m/s and 1.61 to 2.00 m/s respectively.

Indian Ocean Tsunami (IOT) had a major impact on the geomorphology and sedimentology of the east coast of India. Estimation of the magnitude of the tsunami from its deposits is a challenging topic to be developed in studies on tsunami hazard assessment. Two core sediments (C1 and C2) from Nagapattinam, southeast coast of India were subjected to textural, mineral, geochemical and rock-magnetic measurements. In both cores, three zones (zone I, II and III) have been distinguished based on mineralogical, geochemical and magnetic data. Zone II is featured by peculiar rockmagnetic, textural, mineralogical and geochemical signatures in both sediment cores that we interpret to correspond to the 2004 IOT deposit. Textural, mineralogical, geochemical and rock-magnetic investigations showed that the tsunami deposit is featured by relative enrichment in sand, quartz, feldspar, carbonate, SiO 2 , TiO 2 , K 2 O and CaO and by a depletion in clay and iron oxides. These results point to a dilution of reworked ferromagnetic particles into a huge volume of paramagnetic materials, similar to what has been described in other nearshore tsunami deposits (Font et al. 2010). Correlation analysis elucidated the relationships among the textural, mineral, geochemical and magnetic parameters, and suggests that most of the quartz-rich coarse sediments have been transported offshore by the tsunami wave. These results agreed well with the previously published numerical model of tsunami induced sediment transport off southeast coast of India and can be used for future comparative studies on tsunami deposits.

High species diversity renders benthic diatoms that are useful in assessing environmental impact, as well as an adequate reference for measuring biodiversity in protected areas. Preliminary observations suggested that the Guerrero Negro Lagoon (LGN), located in the Baja California Peninsula, Mexico, is an area with a high diversity of benthic diatoms comprising numerous species of certain genera, orders, class, etcetera, which were not equally diverse or common in other areas, and could thus yield new records for the region. Thus, samples of subtidal sediments from LGN were collected in order to analyze the species composition of epipelic diatoms by means of optical microscopy. The taxonomic study yielded a list with 232 taxa, which comprised 42 centric diatoms (>18%) and 190 pennates from 74 genera; 14 new records for the Mexican Pacific are included. This supported the hypothesis that epipelic diatoms from the LGN subtidal constitute assemblages with a high species richness and numerous taxa characteristic of subtropical regions.

Outer shelf sedimentary records are promising for determining the recurrence intervals of tsunamis. However, compared to onshore deposits, offshore deposits are more difficult to access, and so far, studies of outer shelf tsunami deposits are scarce. Here, an example of studying these deposits is presented to infer implications for tsunami-related signatures in similar environments and potentially contribute to pre-historic tsunami event detections. A multidisciplinary approach was performed to detect the sedimentary imprints left by the 1755 CE tsunami in two cores, located in the southern Portuguese continental shelf at water depths of 58 and 91 m. Age models based on 14C and 210Pbxs allowed a probable correspondence with the 1755 CE tsunami event. A multi-proxy approach, including sand composition, grain-size, inorganic geochemistry, magnetic susceptibility, and microtextural features on quartz grain surfaces, yielded evidence for a tsunami depositional signature, although only a...

Storm-and tsunami-deposits are generated by similar depositional mechanisms making their discrimination hard to establish using classic sedimentologic methods. A promising approach is to use rock magnetism techniques to search for new physical benchmarks of tsunami deposits and to integrate them into a multidisciplinary study. To test our method, we investigate the 1755 Lisbon tsunami deposit from the Boca do Rio estuary and other Tsunami-induced deposits from Algarve (Portugal) and Huelva (Spain), as well as storm-like deposits for comparison. Magnetic methods repose on bulk (magnetic susceptibility, SIRM, Hc) and directional (AMS, paleomagnetism) magnetic properties. Results show that in most cases, the tsunami-induced deposit is featured by a low MS signal due to admixture of quartz (i.e. diamagnetic) from the littoral pit. The similarity of magnetic properties of the tsunami deposit and underlying sediments suggest that the source of the iron oxides is very proximate and issued from the erosion of the latter. Directional data are more problematic, since it depends on the techniques used during sampling, but show coherent AMS patterns when collecting samples from trench or using non-rotating vertical core sampler. In comparison, storm-like deposit has a significantly distinct pattern with no abrupt shift of MS. These results provide new benchmarks for tsunami-induced deposit and their discrimination with storm-like deposits. However, directional results need to be improved by testing other sampling techniques.