The Influence of Sediment Source, Vegetation and Microtopography on Tsunami Deposit Characteristics

Nishimura, Yuichi; Nakamura, Yugo; Putra, Purna Sulastya

doi:10.1142/9789814689977_0181

Cited by 1 publication

(3 citation statements)

References 6 publications

(7 reference statements)

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“…Along the coastal plain, the event layer generally thins and fines landward, with varying thicknesses from several cm in the proximal shore area to 1 cm in the more distal part. Although the coastal plain is relatively flat, with ~ 1 m elevation change along the 100 m long sediment core transect, paleo-microtopography have an important effect on deposit thickness and sedimentary structures of tsunami deposits (Nishimura et al 2015). Therefore, the variable observed thickness and sedimentological structures are likely a direct consequence of the paleo-microtopography.…”

Section: Sedimentologymentioning

confidence: 99%

“…The 1755 Lisbon tsunami deposit at Boca do Rio is characterized as a continuous fining-upward sequence that ranges from coarse sand to clayey sandy silt (Dawson et al 1995). Although the abovementioned similarities are convincing, tsunami deposits are characterized by a wide range of sedimentological characteristics depending on sediment availability and microtopography (Nishimura et al 2015). For example, discontinuous sheets of sands are described at Koh Phra Thong, in southern Thailand (Engel and Brückner 2011).…”

Section: Sedimentologymentioning

confidence: 99%

“…During tsunami inundation and backwash, a vast amount of shoreface and beach sediment is eroded, transported, and redeposited in the coastal environment, and subsequently moved offshore (e.g., Einsele et al 1996;Fujiwara and Kamataki 2007;Goto et al 2011;Paris et al 2010;Sakuna et al 2012;Sugawara et al 2008). The associated tsunami deposits are commonly site specific and characterized by a wide range of sedimentological features depending on coastal geomorphology and microtopography (e.g., Hori et al 2007;Matsumoto et al 2016;Nishimura et al 2015), sediment availability (e.g., Dawson and Shi 2000;Goff et al 2009;Meilianda et al 2010), as well as tsunami magnitude (e.g., Yamaguchi and Sekiguchi 2015;Ishimura and Yamada 2019;Putra et al 2019), and preservation potential (e.g., Brill et al 2020;Goto et al 2012;Spiske et al 2020;Szczuciński 2012). Hence, research on tsunami deposits requires multiproxy sedimentary analyses, including sedimentological, geochemical, and biological approaches (e.g., Goff et al 2010;Judd et al 2017;Ramirez-Herrera et al 2012).…”

Section: Introductionmentioning

confidence: 99%

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A tsunamigenic delta collapse and its associated tsunami deposits in and around Lake Sils, Switzerland

et al. 2021

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Large lacustrine mass movements and delta collapses are increasingly being considered as potential tsunamigenic sources and therefore hazardous for the population and infrastructure along lakeshores. Although historical reports document tsunami events in several lakes in Switzerland, and although the propagation of lake tsunamis has been studied by numerical wave modeling, only little is known about on- and offshore lacustrine tsunami deposits. In Lake Sils, Switzerland, a large prehistoric mass-movement deposit originating from the Isola Delta with a minimum estimated volume of 6.5 × 106 m3 and a basinal thickness of > 6 m in the seismic record has been identified by previous studies and radiocarbon dated to around 700 Common Era. Here, we combine (i) comprehensive sedimentological investigation of sediment cores recovered from the on- and offshore settings, (ii) mineralogical fingerprinting of the inflows from key catchments to characterize sediment provenance, and (iii) numerical tsunami modeling, to test the hypothesis of a tsunamigenic delta collapse in Lake Sils. We observe a clastic event deposit consisting of coarse-grained, fining-upward sand overlying an organic-rich peat deposit in the shallow water. This layer thins and fines landward on the coastal plain. Toward the deeper water (20–40 m), the deposit transforms into a thicker and more heterogeneous sediment package with multiple sequences of fining-upward sand and a well-pronounced clay cap at the top. Radiocarbon dating of the peat underlying the event deposit yields a maximum age of 225–419 calibrated Common Era. The tsunami models, which indicate wave heights reaching up to 5 m, simulate areas of inundation that coincide with the location of event deposits. Based on our results, we propose that the historically undocumented Isola Delta collapse generated a basin-wide tsunami that inundated the lakeshore, transporting large amounts of unconsolidated sediment along the lakeshore toward the coastal plain and into the deeper lake basin.

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Section: Sedimentologymentioning

confidence: 99%

Section: Sedimentologymentioning

confidence: 99%