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

• DOI: 10.1111/bor.12635
• Publication Date: 2023-10-08T14:32:56Z
• Authors: Max Engel; Katharina Hess; Sue Dawson; Tasnim Patel; Andreas Koutsoden...; Polina Vakhrameeva; Eckehard Klemt; Philipp Kempf; Isa Schön; Vanessa M. A. Hey...
• Keywords: Overwash; Shetland; Lithology

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