Sedimentological storm and tsunami record of Loch Flugarth, Shetland Islands (UK)

• Other Authors: Hess, Katharina, Engel, Max, Koutsodendris, Andreas
• Format: Other/Unknown Material
• Language: English
• Published: heiDATA 2024
• Subjects: Natural hazards; Little Ice Age; North Atlantic Oscillation (NAO); North Sea; Sand overwash; Storm frequency; Tsunami deposit; Hess; North Atlantic; North Atlantic oscillation; North East Atlantic
• Online Access: http://hdl.handle.net/1942/41996; https://doi.org/10.11588/data/QJEZHT

This dataset comprises the geochemical and sedimentological results of both publications Hess et al., 2023 and Engel et al., 2023. Hess et al., 2023: Severe storm flooding poses a major hazard to the coasts of north-western Europe. However, the long-term recurrence patterns of extreme coastal flooding and their governing factors are poorly understood. Therefore, high-resolution sedimentary records of past North Atlantic storm flooding are required. This multi-proxy study reconstructs storm-induced overwash processes from coastal lake sediments on the Shetland Islands using grain-size and geochemical data, and the re-analysis of historical data. The chronostratigraphy is based on Bayesian age–depth modelling using accelerator mass spectrometry 14C and 137Cs data. A high XRF-based Si/Ti ratio and the unimodal grain-size distribution link the sand layers to the beach and thus storm-induced overwash events. Periods with more frequent storm flooding occurred 980–1050, 1150–1300, 1450–1550, 1820–1900 and 1950–2000 ce, which is largely consistent with a positive North Atlantic Oscillation mode. The Little Ice Age (1400–1850 ce) shows a gap of major sand layers suggesting a southward shift of storm tracks and a seasonal variance with more storm floods in spring and autumn. Warmer phases shifted winter storm tracks towards the north-east Atlantic, indicating a possible trend for future storm-track changes and increased storm flooding in the northern North Sea region. Engel et al., 2023: 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 ...