The relationship between subsurface tsunami features and surface landforms

Buck, Lucy; Bristow, Charlie S.

doi:10.1190/gpr2020-071.1

Cited by 2 publications

(5 citation statements)

References 18 publications

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“…2006). It can also be traced in ground‐penetrating radar measurements (Buck & Bristow 2020). The sand layer is bracketed by two overlapping 14 C dates: 0–1 cm below the sand layer, 1546–1345 cal.…”

Section: Discussionmentioning

confidence: 99%

“…2015; Cascalho et al . 2016; Buck & Bristow 2020), with summaries of the findings presented in Smith et al . (2004, 2019), Long (2015), Costa et al .…”

mentioning

confidence: 94%

“…Despite an apparent scarcity of tsunamis in the shallow North Sea basin, the Shetland Islands have become an important field laboratory in which to study tsunami deposits since the early 1990s (Smith 1993;Bondevik et al 2003Bondevik et al , 2005Dawson et al 2006Dawson et al , 2020bCosta et al 2015;Cascalho et al 2016;Buck & Bristow 2020), with summaries of the findings presented in Smith et al (2004Smith et al ( , 2019, Long (2015), Costa et al (2021) and Bondevik (2022). The original studies on Shetland have played a substantial role in the advancement of tsunami sedimentology and wider tsunami geoscience.…”

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confidence: 99%

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Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

Engel,

Hess,

Dawson

et al. 2023

Boreas

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Tsunami deposits around the North Sea basin are needed to assess the long‐term hazard of tsunamis. Here, we present sedimentary evidence of the youngest tsunami on the Shetland Islands from Loch Flugarth, a coastal lake on northern Mainland. Three gravity cores show organic‐rich background sedimentation with many sub‐centimetre‐scale sand layers, reflecting recurring storm overwash and a sediment source limited to the active beach and uppermost subtidal zone. A basal 13‐cm‐thick sand layer, dated to 426–787 cal. a CE based on 14C, 137Cs and Bayesian age–depth modelling, was found in all cores. High‐resolution grain‐size analysis identified four normally graded or massive sublayers with inversely graded traction carpets at the base of two sublayers. A thin organic‐rich ‘mud’ drape and a ‘mud’ cap cover the two uppermost sublayers, which also contain small rip‐up clasts. Grain‐size distributions show a difference between the basal sand layer and the coarser and better sorted storm layers above. Multivariate statistical analysis of X‐ray fluorescence core scanning data also distinguishes both sand units: Zr, Fe and Ti dominate the thick basal sand, while the thin storm layers are high in K and Si. Enriched Zr and Ti in the basal sand layer, in combination with increased magnetic susceptibility, may be related to higher heavy mineral content reflecting an additional marine sediment source below the storm‐wave base that is activated by a tsunami. Based on reinterpretation of chronological data from two different published sites and the chronostratigraphy of the present study, the tsunami seems to date to c. 1400 cal. a BP. Although the source of the tsunami remains unclear, the lack of evidence for this event outside of the Shetland Islands suggests that it had a local source and was smaller than the older Storegga tsunami (8.15 cal. ka BP), which affected most of the North Sea basin.

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Section: Discussionmentioning

confidence: 99%

“…2015; Cascalho et al . 2016; Buck & Bristow 2020), with summaries of the findings presented in Smith et al . (2004, 2019), Long (2015), Costa et al .…”

mentioning

confidence: 94%

mentioning

confidence: 99%

See 1 more Smart Citation

Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

Engel,

Hess,

Dawson

et al. 2023

Boreas

View full text Add to dashboard Cite

show abstract

“…2 km(Dawson et al, 2006; Tappin et al, 2015) and can also be traced in ground-penetrating radar measurements(Buck and Bristow, 2020). The sand layer is bracketed by two strongly overlapping14 C dates: 0-1 cm below the sand layer, 1546-1345 cal.…”

mentioning

confidence: 93%

“…Despite an apparent scarcity of tsunamis in the shallow North Sea basin, the Shetland Islands have become an important eld laboratory in which to study tsunami deposits since the early 1990s (Smith, 1993;Bondevik et al, 2003Bondevik et al, , 2005Dawson et al, 2006Dawson et al, , 2020aCosta et al, 2015;Cascalho et al, 2016;Buck and Bristow, 2020), with summaries of the ndings presented in Smith et al (2004Smith et al ( , 2019, Long (2015), Costa et al (2021) and Bondevik (2022). The original studies on Shetland have played a substantial role in the advancement of tsunami sedimentology and wider tsunami geoscience.…”

Section: Introductionmentioning

confidence: 99%

The late Holocene tsunami in the Shetland Islands (UK) identified in Loch Flugarth, north Mainland

Engel

Hess

Dawson

et al. 2023

Preprint

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To assess the long-term hazard of tsunamis, particularly in regions with a short and fragmented historical record, sedimentary deposits of tsunamis are an essential tool. In the North Sea region, evidence of tsunamis is scarce. The Shetland Islands are an exception, as they contain abundant deposits of the Storegga tsunami (c. 8150 cal. a BP), and additionally more fragmented evidence of younger tsunami events c. 5500 and c. 1500 cal. a BP. Sediments of the youngest tsunami (the “Dury Voe” event) have only been found at two sites so far, marked by thin landward fining and landward thinning sand sheets which are vertically confined by peat. Here, we present sedimentary evidence for the youngest Shetland tsunami from the small coastal lake of Loch Flugarth, northern Mainland. Three gravity cores of up to 91.7 cm length were taken behind the barrier separating the lake from a shallow marine embayment. The cores show organic-rich background deposition with many sub-cm-scale sand layers, reflecting recurring storm overwash and a sediment source limited to the active beach and uppermost subtidal zone. A basal 13 cm-thick sand layer, dated to 426–787 cal. a CE based on 14C, 137Cs and Bayesian age-depth modelling, was found in all three cores. High-resolution grain-size analysis identified four normally graded sublayers with inversely graded traction carpets in the lower part of two sublayers. An organic-rich ‘mud’ drape and ‘mud’ cap cover the upper two sublayers, which also contain small rip-up clasts. Grain-size distributions show a difference between the basal sand layer and the coarser and better sorted thin storm layers. Principal component analysis of X-ray fluorescence core scanning data also distinguishes both sand units: Zr, Fe and Ti dominate the basal sand, while the thin storm layers are high in K and Si. The enrichment of the basal sand layer in Zr and Ti, in combination with increased magnetic susceptibility, may be related to higher heavy mineral content in the basal sand reflecting the additional marine sediment source of a tsunami deposit below the storm-wave base. Based on reinterpretation of chronological data from the two published sites and the chronostratigraphy of the present study, the Dury Voe tsunami seems to be slightly younger, i.e., closer to 1400 cal. a BP. Although the source of the tsunami remains unclear, the lack of evidence for this event outside of the Shetlands suggests that it was smaller than the older Storegga tsunami, which affected most of the North Sea basin.

show abstract

The relationship between subsurface tsunami features and surface landforms

Cited by 2 publications

References 18 publications

Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

Sedimentary evidence of the Late Holocene tsunami in the Shetland Islands (UK) at Loch Flugarth, northern Mainland

The late Holocene tsunami in the Shetland Islands (UK) identified in Loch Flugarth, north Mainland

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