The Holocene Storegga Slide tsunami in the United Kingdom

All currently known sites in the United Kingdom with evidence for the Holocene Storegga Slide tsunami are described. Information on the altitude, distribution, stratigraphical context, age, particle size profile and microfossil characteristics of the deposits is presented. The tsunami involved a greater area than previously described, reaching a coastline over 600km long. The ubiquitous sand layer which forms the main deposit associated with the event is shown to exhibit a consistent morphology and a particle size profile marked by fining-upwards sequences. An analysis of new and previously published radiocarbon dates indicates that from evidence in the United Kingdom, the event took place sometime around 7100radiocarbon years BP (7900 calibrated years BP). A new isobase model for mainland Scotland and adjacent areas, providing a preliminary estimate of land uplift since the tsunami, is presented. The model estimates contemporary sea surface level offshore at 14m below the present day mean high water spring tides. Tsunami sediment run-up is greatest in inlets, where it reaches at least 25m on Shetland and at least 5m along the mainland coastline to the south, and run-up of the tsunami would have exceeded these values. The tsunami sediments identified here are considered particularly valuable as a synchronous marker horizon. © 2004 Elsevier Ltd. All rights reserved.