Tsunami Deposit Research: Fidelity of the Tsunami Record, Ephemeral Nature, Tsunami Deposits Characteristics, Remobilization of Sediment by Later Waves, and Boulder Movements

Late Miocene to Pliocene Tsunami Deposits in Tegal Buleud, South Sukabumi, West Java, Indonesia

Modern Applied Science ◽

10.5539/mas.v13n12p80 ◽

2019 ◽

Vol 13 (12) ◽

pp. 80

Author(s):

Yan Rizal ◽

Aswan Aswan ◽

Jahdi Zaim ◽

Mika R. Puspaningrum ◽

Wahyu D. Santoso ◽

...

Keyword(s):

Late Miocene ◽

Flame Structure ◽

Tectonic Activity ◽

Tsunami Deposit ◽

Size Distributions ◽

Volcanic Island ◽

Tsunami Deposits ◽

West Java ◽

Foraminiferal Assemblage ◽

Grain Size Distributions

Java is a volcanic island arc formed by the northwards subduction of the Eurasian and Australian Plates. Due to this active subduction, Java has been frequently shocked by earthquakes, which might induce tsunami events. However, there are hardly any ancient geological records of tsunami events in the area. This study aims to determine the presence and to identify sedimentary characters of tsunami deposit in Tegal Buleud, South Sukabumi, West Java. In the study area, there were 4 tsunami layers which were found as thin intercalation within the claystone layer of the Bentang Formation. Those paleotsunami deposits characterized by the occurrence of irregular/disturbed structure such as siltstone rip up, clay clasts, and flame structure occur in normal graded bedding sandstone layer. The grain-size distributions show bimodal and multimodal patterns, with mixing of marine microfossils from inner and middle neritic. The planktonic foraminiferal assemblage indicates that the age of the sediment comparable to N19 (equivalent to Late Miocene - Early Pliocene, at about 5.33 – 3.6 Ma), suggested that these paleotsunami layers were deposited due to the Mio-Pliocene tectonic activity. All the paleotsunami deposits found in Study area are the first and oldest tsunami deposit recorded in Java even in Indonesia. With the discovery of the previously unexplored Late Miocene to Pliocene tsunami deposits found in the study area, the result of this study can be used as a reference for the identification of the Tertiary tsunami deposits present in other parts of Indonesia.

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Reconstruction of Tsunami Occurrence on Okushiri Island, Southwestern Hokkaido, Japan

10.21203/rs.3.rs-951436/v1 ◽

2021 ◽

Author(s):

Atsushi Urabe ◽

Yoshihiro Kase ◽

Gentaro Kawakami ◽

Kenji Nishina ◽

Yasuhiro Takashimizu ◽

...

Keyword(s):

Japan Sea ◽

Tsunami Deposit ◽

Fault Activity ◽

Tsunami Deposits ◽

Tectonic Zone ◽

Tectonic Plates ◽

Eastern Margin ◽

The North ◽

The Japan Sea ◽

Okushiri Island

Abstract The eastern margin of the Japan Sea is located along an active convergent boundary between the North American and Eurasian tectonic plates. Okushiri Island, which is situated off the southwest coast of Hokkaido, is located in an active tectonic zone where many active submarine faults are distributed. Studying the records of past tsunamis on Okushiri Island is important for reconstructing the history and frequency of fault activity in this region, as well as the history of tsunamis in the northern part of the eastern margin of the Japan Sea. Five tsunami deposit horizons have been identified previously on Okushiri Island, including that of the 1741 tsunami, which are interbedded in the coastal lowlands and Holocene terraces. However, these known tsunami deposits date back only ~3,000 years. A much longer record of tsunami occurrence is required to consider the frequency of submarine fault activity. In this study, we cored from 7 to 25 m depth in the Wasabiyachi lowland on the southern part of Okushiri Island, where previous studies have confirmed the presence of multiple tsunami deposits on peat layer surfaces. The results indicate that the Wasabiyachi lowland comprises an area that was obstructed by coastal barriers between the lowland and the coast at ~8.5 ka and consists of muddy sediment and peat layers formed in lagoons and floodplains, respectively. In addition, event deposits and 15 tsunami horizons were observed among the turbidites and peat layers, dating back as far as 3,000 years. Combined with previous findings, Okushiri Island has sustained 20 tsunami events between ~7.5 ka and the present. These findings are critical for investigating the activities of submarine faults off the southwestern coast of Hokkaido, as well as for determining tsunami risks along the coast of the Japan Sea between North Tohoku and Hokkaido.

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Numerical Simulations of the 2004 Indian Ocean Tsunami Deposits Thicknesses and Emplacements

10.5194/nhess-2018-348 ◽

2018 ◽

Author(s):

◽

Musa Al'ala ◽

Hermann M. Fritz ◽

Mirza Fahmi ◽

Teuku Mudi Hafli

Keyword(s):

Sediment Transport ◽

Indian Ocean ◽

Numerical Simulations ◽

Field Data ◽

Numerical Models ◽

Indian Ocean Tsunami ◽

Tsunami Deposit ◽

Field Observations ◽

Tsunami Deposits ◽

2004 Indian Ocean Tsunami

Abstract. After more than a decade of recurring tsunamis, identification of tsunami deposits, a part of hazard characterization, still remains a challenging task not fully understood. The lack of sufficient monitoring equipment and rare tsunami frequency are among the primary obstacles that limit our fundamental understanding of sediment transport mechanisms during a tsunami. The use of numerical simulations to study tsunami-induced sediment transport was rare in Indonesia until the 2004 Indian Ocean tsunami. This study aims to couple two hydrodynamic numerical models in order to reproduce tsunami-induced sediment deposits, i.e., their locations and thicknesses. Numerical simulations were performed using the Cornell Multi-Grid Coupled Tsunami Model (COMCOT) and Delft3D. This study reconstructed tsunami wave propagation from its source using COMCOT, which was later combined with Delft3D to map the location of the tsunami deposits and calculate their thicknesses. Two Dimensional-Horizontal (2DH) models were used as part of both simulation packages. Lhoong, in the Aceh Besar District, located approximately 60 km southwest of Banda Aceh, was selected as the study area. Field data collected in 2015 and 2016 validated the forward modeling techniques adopted in this study. However, agreements between numerical simulations and field observations were more robust using data collected in 2005, i.e., just months after the tsunami (Jaffe et al., 2006). We conducted pit (trench) tests at select locations to obtain tsunami deposit thickness and grain size distributions. The resulting numerical simulations are useful when estimating the locations and the thicknesses of the tsunami deposits. The agreement between the field data and the numerical simulations is reasonable despite a trend that overestimates the field observations.

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Identification of suspected paleotsunami deposits study from Karapyak Beach, Pangandaran area, West Jawa, Indonesia

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.36.2.2021.727 ◽

2021 ◽

Vol 36 (2) ◽

Author(s):

Aswan Aswan ◽

Yan Rizal

Keyword(s):

Thin Layer ◽

Energy Flow ◽

Fine Sand ◽

High Energy ◽

Grain Size Analysis ◽

Size Analysis ◽

Tsunami Deposit ◽

Tsunami Deposits ◽

Rock Fragments ◽

Coarse Grains

Identifying and constraining palaeotsunami deposits can be a vital tool for establishing the periodicity of earthquakes and their associated tsunami events beyond the historical records. However, the deposits can be difficult to establish and date. In this study we used the characteristics of the 2006 Pangandaran tsunami deposit as a reference for identification of paleotsunami deposits in Karapyak Beach, Pangandaran area, West Java, Indonesia. Similar to the 2006 Pangandaran tsunami deposit, the Karapyak Beach paleotsunami deposit is characterized by light brown loose sand materials overlying a dark brown paleosoil layer with erosional contact. A thin layer that varies in thickness is locally found right above the erosional contact, with non-laminated coarser grain in the lower part that gradually change into medium to fine sand-sized in upper part. The base of the lower part is rich with broken mollusc shells and corals, and the mid-top of the lower part may contain several intact molusc shells and corals, rock fragments and anthropogenic products (rooftile). Those types of fragments are absent in the upper part of the thin layer. Grain size analysis shows a mixture of fine and coarse grains in the lower part of 2006 tsunami deposits as well as in the suspected paleotsunami deposits, suggesting uprush high energy flow during sedimentation. Fining upward sequence above mixed grain layers reflects waning flow or pre-backwash deposition. Foraminifera analysis also shows a mixture of shallow and deep marine foraminifera in the two deposits. Based on the characteristics of the 2006 tsunami deposits, there are at least four identified paleotsunami deposits at Karapyak Beach, Pangandaran area.

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Organic geochemical analysis of multiple tsunami deposits of the last century at the Aomori coast (Northern Japan)

10.5194/egusphere-egu2020-7824 ◽

2020 ◽

Author(s):

Mike Frenken ◽

Piero Bellanova ◽

Yuichi Nishimura ◽

Jan Schwarzbauer ◽

Klaus Reicherter

Keyword(s):

Soil Layer ◽

Strong Increase ◽

Coastal Protection ◽

Tsunami Deposit ◽

Field Site ◽

Tsunami Deposits ◽

Anthropogenic Markers ◽

Eyewitness Reports ◽

Polycyclic Aromatic ◽

Northern Japan

Japan, more precisely, the eastern coastal areas of Honshu, are one of the most affected areas of tsunamis in the world. Major events within the last century were three Sanriki-oki tsunamis (1896, 1933, 1968), and the most recent 2011 Tohoku-oki tsunami, triggered by the 9.1&#160;MW Tohoku-oki earthquake, which caused massive damage along the coastlines.The 2011 Tohoku-oki tsunami overtopped the coastal defense walls with waves of 6-10&#160;m height along the shores of the Aomori Prefecture in Northern Japan. The inundation reached up to 550 m inland, however, sandy tsunami deposits are limited to 250 &#8211; 350 m of the total inundation distance. At the field site of Misawa Harbor the well-preserved identifiable tsunami remains show up to 18 cm thick sand layers with sedimentary features, such as fining upward sequences, mud caps and rip-up clasts. The sandy deposits were enclosed in the soil of the coastal protection forest. Along with the sedimentary record of the tsunami, the use of organic geochemical indicators can provide a better understanding of the extend and processes, such as the deposition of tsunami layers and the backwash, of the inundation by the 2011 Tohoku-oki tsunami. The devastating damages caused by the interaction of tsunami and earthquake released pollutants associated as biological and anthropogenic markers. These released pollutants give the tsunami deposit an unique geochemical signature, that is distinguishable from the background sedimentation. Organic-geochemical results reveal a strong increase of anthropogenic (polycyclic aromatic hydrocarbons, pesticides and chlorinated compounds) and a variation of biological markers (i.e. n-alkanes, fatty acids) in the 2011 tsunami deposit close to the fishery port. During the analysis of the samples, another variation of biomarker and anthropogenic marker were identified right below the soil layer of the current forest. This layer is as well distinguishable from the paleo-dune that marks the lowest sedimentological unit at the field site. This differentiation shows the likely impact of a historical Sanriki-oki tsunami (1896, 1933 or 1968). These organic geochemical results in combination with local eyewitness reports of the tsunamis and lead to the assumption that the sedimentary archive of the Aomori coastline contains and preserved at two or more tsunami events of the last century.The inclusion of organic geochemical markers to expand the characterizing and identifying proxies used in tsunami research are important to get a better understanding of the processes and deposition during tsunamis. Furthermore, this method can detect tsunami deposits beyond the visible recognizability of sedimentological identification of tsunami deposits and therefore can serve as a blue-print for historical and paleo-tsunami studies, as most of them only rely on visible sand deposits as marker for inundation distances from the beach. The high-resolution geochemical application can gain more information than standard techniques, like the identification of the &#8220;invisible&#8221; tsunami layer exceeding the limits of sandy deposits or the deposition in similar sedimentary textures, capturing a broader picture of the event.

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A record of local storms and trans-Pacific tsunamis, eastern Banks Peninsula, New Zealand

The Holocene ◽

10.1177/0959683616670222 ◽

2016 ◽

Vol 27 (4) ◽

pp. 496-508 ◽

Cited By ~ 10

Author(s):

Jai Donnelly ◽

James Goff ◽

Catherine Chagué-Goff

Keyword(s):

New Zealand ◽

Tsunami Deposit ◽

Sediment Characteristics ◽

Tsunami Deposits ◽

The World ◽

Lateral Extent ◽

Storm Deposits ◽

First Time ◽

Grain Size Parameters ◽

Tsunami Sediments

This study of five sand units at Lavericks Bay, New Zealand, reports on the sedimentary evidence for three trans-Pacific tsunamis and two local storms. The 1868 Arica, 1877 Iquique and 1960 Valdivia tsunamis from Chile were the largest distantly generated events in New Zealand’s history but have never before been identified at the same location. It is also the first time that the 1877 Iquique tsunami deposit has been found in New Zealand. Two further sand units were identified as local storm deposits laid down in 1869/1870 and 1929. The identification and chronology of these events were established through the use of geochemistry, palynology, diatoms, charcoal abundance and historical documents. Their relative magnitudes were estimated through the use of grain size parameters and lateral extent of the recognisable sand layers. The recognisable sandy tsunami deposits extend about 60% of the inundation distance, while the storm sediments are finer and less extensive. There were two notable geochemical differences between the storm and tsunami deposits. Both storm deposits had lower concentrations of marine proxy elements associated with lower Ca–Ti and Sr–Ba ratios. Other differences were noted between some of the tsunami and storm deposits such as rip-up clasts and sediment characteristics, but these were by no means unequivocal. It is possible that geochemistry may prove to be the only proxy capable of not only differentiating effectively between storm and tsunami sediments but also identifying the maximum inland extent of a deposit and of inundation. It is the ability to better understand the nature and extent of such catastrophic events through these subtle differences in event characteristics that will help improve risk management for coastlines around the world.

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Application of Binary Diagnostic Ratios of Polycyclic Aromatic Hydrocarbons for Identification of Tsunami 2004 Backwash Sediments in Khao Lak, Thailand

The Scientific World JOURNAL ◽

10.1155/2014/485068 ◽

2014 ◽

Vol 2014 ◽

pp. 1-14 ◽

Cited By ~ 9

Author(s):

Siwatt Pongpiachan

Keyword(s):

Polycyclic Aromatic Hydrocarbons ◽

Marine Sediments ◽

Aromatic Hydrocarbons ◽

Organic Molecules ◽

Three Dimensional ◽

Diagnostic Ratios ◽

Tsunami Deposit ◽

Tsunami Deposits ◽

Sedimentary Characteristics ◽

Polycyclic Aromatic

Identification of Tsunami deposits has long been a controversial issue among geologists. Although there are many identification criteria based on the sedimentary characteristics of unequivocal Tsunami deposits, the concept still remains ambiguous. Apart from relying on some conventional geological, sedimentological, and geoscientific records, geologists need some alternative “proxies” to identify the existence of Tsunami backwash in core sediments. Polycyclic aromatic hydrocarbons (PAHs) are a class of very stable organic molecules, which can usually be presented as complex mixtures of several hundred congeners; one can assume that the “Tsunami backwash deposits” possess different fingerprints of PAHs apart from those of “typical marine sediments.” In this study, three-dimensional plots of PAH binary ratios successfully identify the Tsunami backwash deposits in comparison with those of global marine sediments. The applications of binary ratios of PAHs coupled with HCA are the basis for developing site-specific Tsunami deposit identification criteria that can be applied in paleotsunami deposits investigations.

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SEDIMENTOLOGICAL PROPERTIES OF THE 2010 MENTAWAI TSUNAMI DEPOSIT

BULLETIN OF THE MARINE GEOLOGY ◽

10.32693/bomg.27.2.2012.45 ◽

2016 ◽

Vol 27 (2) ◽

pp. 55

Author(s):

Yudhicara Yudhicara ◽

Andrian Ibrahim

Keyword(s):

Grain Size ◽

Fine Sand ◽

Coarse Sand ◽

Transport Processes ◽

Grain Size Analysis ◽

Size Analysis ◽

Tsunami Deposit ◽

Tsunami Deposits ◽

Sponge Spicule ◽

Run Up

Post tsunami survey of the October 25, 2010, Mentawai tsunami, has been carried out by a collaboration team of Indonesian-German scientists from 20 to 28 November 2010. One activity of the researches were investigation on tsunami deposits along the coast following the event that devastated the islands of Sipora, North Pagai and South Pagai. Sedimentological properties of Mentawai tsunami deposit were explained by this study, from both megascopic and laboratory result. In general, beaches along the study area are underlying by a stretch of reef limestone, sediments mostly composed of white sand while grey sand was found only at Malakopa. Tsunami sediments were taken from 20 locations, start from Betumonga at Sipora Island until Sibaru-baru Island at the southern tip of the study area. The thickness of tsunami deposits are ranged between 1.5 and 22 cm, which are generally composed of fine to coarse sand in irregular boundaries with the underlying soil. Based on grain size analysis, variation of sedimentological properties of tsunami deposits range between phi=-0,5793 and phi=3,3180 or very coarse to very fine sand. Tsunami deposits mostly have multiple layers which described their transport processes, run up at the bottom and back wash at the top. Structural sediments such as graded bedding of fining upward, parallel lamination and soil clast were found. The grain size distribution curves show two types of mode peak, unimodal and multimodal which are indication of different sorting condition representing the source materials. While segment grain size accumulative plot generally shows domination of dilatation and traction transport mechanism rather than suspension. In general, very rare fossils were found from Mentawai tsunami deposit, but those findings gave information on how depth tsunami start to scour the seafloor and transport it landward, such as an abundance of Sponge spicule was found which indicate shallow water environments (20-100 m seafloor depth). Keywords: 2010 Mentawai tsunami, tsunami deposit, grain size analysis, fossils identification. Survei pasca-tsunami Mentawai 25 Oktober 2010, telah dilakukan oleh Tim gabungan Indonesia-Jerman pada tanggal 20 - 28 November 2010. Salah satunya adalah melakukan identifikasi endapan tsunami yang ditemukan di sepanjang pantai yang terlanda tsunami di Pulau Sipora, Pagai Utara dan Pagai Selatan. Berdasarkan hasil penelitian baik megaskopik maupun analisis laboratorium, dalam tulisan ini dapat dijelaskan mengenai sifat-sifat sedimentologi dari endapan tsunami Mentawai. Secara umum litologi penyusun pantai di daerah penelitian disusun oleh hamparan batugamping terumbu, sebagian disusun oleh pasir berwarna putih, sedangkan di Malakopa tersusun oleh endapan pasir pantai berwarna abu-abu. Berdasarkan hasil analisis laboratorium, diperoleh variasi sifat sedimentologi, seperti kisaran ukuran butir endapan tsunami antara -0,5793 phi dan 3,3180 phi, yaitu pasir sangat kasar hingga sangat halus. Endapan tsunami umumnya memiliki beberapa lapis yang menunjukkan adanya proses transportasi, seperti saat air naik (run up) di lapisan bagian bawah dan surut di bagian atas, yang ditunjukkan dengan adanya perbedaan ukuran butir. Struktur sedimen ditemukan seperti adanya perubahan besar butir secara berangsur menghalus ke bagian atas, perlapisan sejajar dan fragmen tanah yang terperangkap dalam sedimen. Kurva distribusi ukuran butir memperlihatkan dua jenis model puncak, yaitu unimodal dan multimodal yang memperlihatkan kondisi pemilahan yang berbeda yang menunjukkan kondisi sumber material endapan tsunami, sedangkan grafik akumulasi ukuran butir umumnya memperlihatkan dominasi mekanisme transportasi dilatasi dan traksi daripada suspensi. Secara umum fosil yang terkandung dalam endapan tsunami Mentawai sangat jarang, namun sedikit banyak telah memberikan informasi seberapa dalam gelombang tsunami mulai menggerus lantai samudera dan memindahkannya ke darat, misalnya dengan ditemukannya fosil bentonik Sponge spicule yang melimpah, menunjukkan asal lingkungan laut dangkal dengan kedalaman laut 20-100 m. Kata kunci: Tsunami Mentawai 2010, endapan tsunami, analisis besar butir, identifikasi fosil.

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Millennial paleotsunami history at Minna Island, southern Ryukyu Islands, Japan

Progress in Earth and Planetary Science ◽

10.1186/s40645-020-00365-9 ◽

2020 ◽

Vol 7 (1) ◽

Cited By ~ 1

Author(s):

Ryosuke Fujita ◽

Kazuhisa Goto ◽

Yasufumi Iryu ◽

Tomoya Abe

Keyword(s):

High Elevation ◽

Stratigraphic Correlation ◽

Ryukyu Islands ◽

Tsunami Deposit ◽

Tsunami Deposits ◽

Tsunami Waves ◽

The Ryukyu Islands ◽

History Of ◽

Age Range ◽

Large Tsunami

Abstract Huge tsunami waves have repeatedly bombarded the southern end of the Ryukyu Islands (Miyako and Yaeyama Islands, southwestern Japan) at several-hundred-year intervals. Therefore, clarifying the islands’ paleotsunami history is important for risk assessment. Nevertheless, discrepancies of paleotsunami histories exist among regional studies of tsunami boulders and sandy tsunami deposits. Radiocarbon ages of tsunami boulders indicate that tsunami events of the last 2400 years have occurred every 150–400 years, most recently the historical 1771 Meiwa tsunami. Sandy tsunami deposits at Yaeyama Islands show that four tsunami events of the last 2000 years struck the islands at approximately 600-year intervals. Sandy tsunami deposits of the Miyako Islands have been studied only rarely. Therefore, studying sandy tsunami deposits in the Miyako Islands is crucially important for clarifying the paleotsunami history of this region. We conducted a trench survey on Minna Island, located among the westernmost Miyako Islands, which revealed two sandy tsunami deposits under a coral tsunami boulder transported by the 1771 tsunami. The upper tsunami deposit was likely deposited by the 1771 tsunami, as inferred from stratigraphic correlation to the tsunami boulder. However, the lower tsunami deposit was probably deposited 700–1000 years ago, which is consistent with the age range of the paleotsunami reported for Yaeyama Islands. Because sandy tsunami deposits found in this and earlier studies are thick and deposited at high elevation and far inland, these are useful markers of large tsunami events similar to the 1771 event. However, the reported tsunami boulders of various sizes are deposited along the coast and reefs: they can be formed not only by large tsunami events but also by small ones. It is noteworthy that each tsunami deposit is coarse and thick (40–48 cm) relative to the island elevation (about 12 m maximum, 7 m above the mean sea level at the study site). By assuming that tsunamis have affected this region repeatedly during the past few thousand years at around 600-year intervals, tsunamis might have been important geomorphic agents for building up small reef-surrounded islands such as Minna Island.

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Heavy minerals analysis on tsunami deposits from Misawa (Japan)

10.5194/egusphere-egu2020-18726 ◽

2020 ◽

Author(s):

João Cascalho ◽

Ana Abrantes ◽

Pedro Costa ◽

Piero Bellanova ◽

Mike Frenken ◽

...

Keyword(s):

Heavy Mineral ◽

Heavy Minerals ◽

Tsunami Deposit ◽

Mineral Analysis ◽

Sediment Sources ◽

Tsunami Deposits ◽

Sediment Fraction ◽

Mineral Assemblages ◽

Storm Deposits ◽

Heavy Mineral Analysis

Heavy minerals in tsunami and storm deposits have been used to establish sediment sources and to infer the inundation and backwash phases (Morton et al., 2007). The abundance of these minerals is dependent on the hydrodynamic conditions that existed during transport and depositional stages. Overall, heavy mineral analysis allowed interpretations on sediment dynamics. Heavy mineral studies on tsunami deposits allowed the establishment of source-to-sink relationships thus, contributed to establish transport paths and inundation routes (Jagodzinski et al., 2012; Putra et al., 2013; Costa et al., 2015; Cascalho et al., 2016).After the Tohoku-oki tsunami event, GeoSlicer were excavated and tsunami imprints were retrieved from the slices in Misawa coastal area (Japan). Heavy minerals from thirty-six samples were analyzed. Heavy minerals in the sediment fraction of 0.125-0.500 mm were separated by centrifugation in sodium polytungstate (2.90 kg/m3) and recovered by partial freezing with liquid nitrogen. An average of about 220 transparent heavy-mineral grains per sample were identified and counted under a petrographic microscope. Heavy minerals not mounted on glass slides were subjected to the ferromagnetic separation using a Frantz Isodynamic Magnetic apparatus to estimate the weight of magnetite in each sample.Heavy-mineral weight in total sediment fraction presented a mean value of 31%, ranging between 18 and 59%. The magnetite weight percentage present in the heavy-mineral fraction has a mean of 26% ranging between 14 and 43%.Considering the mean frequency of the transparent heavy minerals it was identified the presence of orthopyroxenes (67%), followed by clinopyroxenes (30%).These results indicate that the main original source of heavy minerals are basic volcanic rocks. The wide ranges of variation of the total heavy mineral fraction and the magnetite present in that fraction provides useful information about the flow competence of the tsunami waves. The samples that reveal higher concentration in total heavy minerals tend to be richer in magnetite. These results could be used to pinpoint water flow conditions (velocity thresholds) promoting grain sorting leading to the formation of layers enriched in heavy minerals. Confirming previous cases, heavy mineral analysis in Misawa tsunami deposit seems to provide useful insights into tsunami-derived sediment dynamic.&#160;&#160;&#160;&#160; &#160;&#160;Cascalho, J., Costa, P., Dawson, S., Milne, F. and Rocha, A. 2016. Heavy mineral assemblages of the Storegga tsunami deposit. Sedimentary geology, 334, 21-33.&#160;&#160;&#160;&#160;&#160;Costa, P.J., Andrade, C., Cascalho, J., Dawson, A.G., Freitas, M.C., Paris, R. and Dawson, S., 2015. Onshore tsunami sediment transport mechanisms inferred from heavy mineral assemblages. The Holocene, 25(5), pp.795-809.Jagodzi&#324;ski, R., Sternal, B., Szczuci&#324;ski, W., Chagu&#233;-Goff, C. and Sugawara, D., 2012. Heavy minerals in the 2011 Tohoku-oki tsunami deposits&#8212;insights into sediment sources and hydrodynamics. Sedimentary Geology, 282, pp.57-64.Morton, R.A., Gelfenbaum, G. and Jaffe, B.E., 2007. Physical criteria for distinguishing sandy tsunami and storm deposits using modern examples. Sedimentary Geology, 200(3-4), pp.184-207.Putra, P.S., Nishimura, Y., Nakamura, Y. and Yulianto, E., 2013. Sources and transportation modes of the 2011 Tohoku-Oki tsunami deposits on the central east Japan coast. Sedimentary Geology, 294, pp.282-293.The author would like to acknowledge the financial support FCT through project UIDB/50019/2020 &#8211; IDL and by FCT OnOff project PTDC/CTAGEO/28941/2017.&#160;

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