First indication of Storegga tsunami deposits from East Greenland BERND WAGNER, 1 * OLE BENNIKE, 2 MARTIN KLUG 3 and HOLGER CREMER 4 1 Baltic Sea Research Institute Warnemu ¨ nde, Warnemu ¨ nde, Germany 2 Geological Survey of Denmark and Greenland, Copenhagen, Denmark 3 Institute for Geophysics and Geology, University Leipzig, Leipzig, Germany 4 Netherlands Organization of Applied Scientific Research TNO, Geological Survey of The Netherlands, Utrecht, The Netherlands Wagner, B., Bennike, O., Klug, M. and Cremer, H. 2006. First indication of Storegga tsunami deposits from East Greenland. J. Quaternary Sci., Vol. 22 pp. 321–325. ISSN 0267–8179. Received 18 April 2006; Revised 29 June 2006; Accepted 13 July 2006 ABSTRACT: A 2.73 m long sediment sequence from Loon Lake, located at 18 m a.s.l. on outer Geographical Society Ø, East Greenland, was investigated for its chronology and changes in physical and biogeochemical properties, macrofossils, and grain-size distribution. The predominance of marine fossils throughout the sequence, dated by 14 C AMS to between 8630 and 7535 cal. yr BP, shows that the Loon Lake at that time was a marine basin, which according to existing sea-level curves was about 15–35 m deep. The sequence mainly consists of fine grained homogeneous sediments, which are interrupted by a 0.72 m thick sandy horizon with erosive basis and distinct fluctuations in the grain-size distribution and in the physical and biogeochemical properties. According to the radiocarbon dates, this sandy horizon was deposited after 8500–8300 cal. yr BP and is interpreted as originating from the Storegga tsunami. The record from Loon Lake provides the first indication of Storegga tsunami deposits from East Greenland. Copyright # 2006 John Wiley & Sons, Ltd. KEYWORDS: Storegga tsunami deposits; relative sea level; Holocene; East Greenland; coastal basin. Introduction The most prominent and largest submarine landslide during the Holocene in the North Atlantic, the so-called second Storegga Slide, occurred ca. 8100 cal. yr BP off the shore of western Norway and displaced between 2400 and 3200 km 3 sediment (Haflidason et al., 2005; Fig. 1). The slide generated a series of major tsunami waves, which reached the adjacent coastal regions within minutes to hours (Dawson et al., 1988; Bondevik et al., 1997a, 2005a). When the tsunami waves reached shallow waters near the coast, wave heights increased dramatically, and large volumes of sediments in the shallower water of the near-coastal regions became eroded and re- deposited. In addition, onshore low-elevation areas were inundated, and in some funnel-shaped fjords the runup exceeded 10 m (Bondevik et al., 2003, 2005a). Deposits related to the Storegga tsunami have been recorded from coastal lakes, raised marine sediments, and peat sequences from eastern Scotland (Dawson et al., 1988; Long et al., 1989; Dawson and Smith, 2000), western Norway (Bondevik et al., 1997b, 2005a; Bondevik, 2003), the Faroe Islands (Grauert et al., 2001), and the Shetland Islands (Bondevik et al., 2005b). In Iceland and Greenland, however, such deposits have not been detected hitherto (cf. Noa Sø, Fig. 1; Wagner and Melles, 2002, Antony Long pers. comm.), although modelling has shown that a 3 m high wave reached the coast of eastern Greenland only 2.5–3 h after the release of the slide (Bondevik et al., 2005a). An unnamed lake, here referred to as Loon Lake (728 53.2 0 N, 0228 08.3 0 W), on outer Geographical Society Ø, East Greenland, was visited during an expedition in the summer 2003 (Bennike et al., 2004; Fig. 1). Loon Lake is today located at 18 m a.s.l. in a lowland area that drains into Kejser Franz Joseph Fjord and the Greenland Sea to the north. According to relative sea-level curves (Funder, 1989; Wagner and Melles, 2002) and unpublished biostratigraphical work in the region, the basin was inundated by the sea after the last deglaciation in the early Holocene (Bennike and Bjo ¨ rck, 2002; Fig. 1). The maximum water depth of Loon Lake today is 11.7 m in its centre, where a 10.25 m long sediment sequence was recovered using gravity and piston corers (both from UWITEC Co., Austria). A compact diamicton at the base of the sequence prevented further penetration into the sediments. Relatively homogeneous, fine- grained sediments form the major part of the sediments above the diamicton. However, one of the piston core segments, covering the sediment depth between 2.51 and 5.24 m, contains a 0.72 m thick horizon that differs markedly in facies from those above and below. A range of geophysical, granulometric, biogeochemical, biological and chronological analyses were carried out in order to evaluate the genesis of this unique horizon. JOURNAL OF QUATERNARY SCIENCE (2007) 22(4) 321–325 Copyright ß 2006 John Wiley & Sons, Ltd. Published online 20 December 2006 in Wiley InterScience (www.interscience.wiley.com) DOI: 10.1002/jqs.1064 * Correspondence to: B. Wagner, Baltic Sea Research Institute Warnemu ¨ nde, Seestr. 15, D-18119 Warnemu ¨ nde, Germany. E-mail: bernd.wagner@io-warnemuende.de