The Storegga tsunami along the Norwegian coast, its age and run up

Abstract

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.

The catastrophic final flooding of Doggerland by the Storegga Slide tsunami

“…This weighted average (7308 ± 28 14 C-BP: 8110 ± 50 calBP) corresponds closely to the date of 7300 14 C-BP (8150 calBP) proposed by Bondevik et al (1997) and Bondevik et al (2003), but disagrees significantly with the result of 8350 calBP obtained by Boomer et al (2007). If the Boomer et al (2007) estimate is correct, then the dating discrepancy poses the question of whether both studies are addressing the same event, and notably whether the event observed at Howick indeed represents the Storegga Slide tsunami.…”

“…In one case, a radiocarbon age was obtained on a stick immediately above the sand layer. Following critical sample selection, Bondevik et al (1997) propose that the tsunami most likely dates to c. 7300 14 C-BP. This age is supported by Bondevik et al (2003), who give a calibrated age value of c. 8150 calBP.…”

“…As a result of detailed fieldwork (e.g. Bondevik et al 1997;2003;Smith et al 2004), followed by comprehensive modelling studies (Harbitz 1992;Bondevik et al 2005), a comparatively large number of deposits on the coasts of Norway and eastern Scotland can now be safely attributed to the Second Storegga Slide tsunami. The generation of the tsunami apparently involved some 2400-3200km 3 of material that spread across the North Atlantic sea floor, altogether covering an area of around 95 000km 2 (Haflidason et al 2005) -that is about the size of Scotland.…”

“…Bondevik 2003;Bondevik et al 1997;2003;Dawson et al 1988;1993;Grauert et al 2001;Haflidason et al 2005;Long et al 1989;Smith et al 1985;. As a result of detailed fieldwork (e.g.…”

Sand Sheets on a Beach-Ridge Plain in Thailand: Identification and Dating of Tsunami Deposits in a Far-Field Tropical Setting

“…Paleotsunami deposits are often identified in lowenergy coastal environments, such as tidal marsh, back-barrier marshes and coastal lakes. Most publications on paleotsunami studies during the past two decades are from temperate zones such as the north Atlantic (Bondevik et al, 1997;Bondevik et al, 2003;Dawson et al, 1988), the circum-Pacific shores of the Americas and Asia (Atwater & Moore, 1992;Atwater et al, 2005;Bourgeois et al, 2006;Cisternas et al, 2005;Fiedorowicz & Peterson, 2002;Kelsey et al, 2005;Minoura & Nakata, 1994;Nanayama et al, 2003;Tuttle et al, 2004) Goff et al, 2001;Goff et al, 1998;Grauert et al, 2001). In many cases tsunami studies occur in conjunction with other evidence for large earthquakes such as the study of coastal geological evidence of past tsunamis and associated post seismic uplift in Japan by Sawai et al (2009b).…”