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Sedimentary successions in small coastal lakes situated from 0 to 11 m above the 7000 year BP shoreline along the western coast of Norway, contain a distinctive deposit, very different from the sediments above and below. The deposit is interpreted to be the result of a tsunami inundating the coastal lakes. An erosional unconformity underlies the tsunami facies and is traced throughout the basins, with most erosion found at the seaward portion of the lakes. The lowermost tsunami facies is a graded or massive sand that locally contains marine fossils. The sand thins and decreases in grain size in a landward direction. Above follows coarse organic detritus with rip‐up clasts, here termed ‘organic conglomerate’, and finer organic detritus. The tsunami unit generally fines and thins upwards. The higher basins (6–11 m above the 7000 year shoreline) show one sand bed, whereas basins closer to the sea level 7000 years ago, may show several sand beds separated by organic detritus. These alternations in the lower basins may reflect repeated waves of sea water entering the lakes. In basins that were some few metres below sea level at 7000 years BP, the tsunami deposit is more minerogenic and commonly present as graded sand beds, but also in some of these shallow marine basins organic‐rich facies occur between the sand beds. The total thickness of the tsunami deposit is 20–100 cm in most studied sites. An erosional and depositional model of the tsunami facies is developed.

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Estimates of the radiocarbon age of seawater are required in correlations between marine and terrestrial records of the late Quaternary climate. We radiocarbon-dated marine shells and terrestrial plant remains deposited in two bays on Norway's west coast between 11,000 and 14,000 years ago, a time of large and abrupt climatic changes that included the Younger Dryas (YD) cold episode. The radiocarbon age difference between the shells and the plants showed that sea surface reservoir ages increased from 400 to 600 years in the early YD, stabilized for 900 years, and dropped by 300 years within a century across the YD-Holocene transition.

Coastal fen-and lake deposits enclose sand layers that record at least three Holocene tsunamis at the Shetland Islands. The oldest is the well-known Storegga tsunami (ca 8100 cal yr BP), which at the Shetlands invaded coastal lakes and ran up peaty hillsides where it deposited sand layers up to 9.2 m above present high tide level. Because sea level at ca 8100 cal yr BP was at least 10-15 m below present day sea level, the runup exceeded 20 m. In two lakes, we also found deposits from a younger tsunami dated to ca 5500 cal yr BP. The sediment facies are similar to those of the Storegga tsunami-rip-up clasts, sand layers, re-deposited material and marine diatoms. Runup was probably more than 10 m. Yet another sand layer in peat outcrops dates to ca 1500 cal yr BP. This sand layer thins and fines inland and was found at two sites 40 km apart and traced to ca 5-6 m above present high tide. The oldest tsunami was generated by the Storegga slide on the Norwegian continental slope. We do not know what triggered the two younger events.

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1997 (March): The Storegga tsunami along the Norwegian coast, its age and runup. Boreas, VoI. 26, pp. 29-53. OSIO. ISSN 0300-9483.The statigraphy in 25 coastal lakes shows that most of the Norwegian coastline was impacted by a large tsunami about 7200 I4C BP. The methodology has been to core a staircase of lake basins above the contemporary sea level in several areas and to map the tsunami deposit to its maximum elevation. The tsunami was identified in the sedimentary record as an erosional unconformity overlain by graded or massive sand with shell fragments, followed by redeposited organic detritus. The greatest recorded runup along the coast (10-11 m above high tide) is found in areas most proximal to the Storegga slide scar on the Norwegian continental slope (Sunnmerre). To the north and south, runup is less, about 6-7 m at Bjugn (250 km north of Sunnmerre) and about 3-5 m in Austrheim (200 km to the south of Sunnmerre). This runup pattern supports the suggestion that the tsunami was generated by the Second Storegga Slide. The recorded runup heights are consistent within and between the investigated areas, and imply that the tsunami wave was not significantly influenced by the local topography, suggesting a very long wave length. The mapped runup estimates are in good agreement with a numerical model of the tsunami generated by the Second Storegga slide, and indicate that the slide was a single major event rather than a set of smaller slides.