Modern and historical tropical cyclone and tsunami deposits at the coast of Myanmar: Implications for their identification and preservation in the geological record

• DOI: 10.1111/sed.12586
• Publication Date: 2019-02-03T10:58:23Z
• Authors: Dominik Brill; Katharina Seeger; Anna Pint; Felix Reize; Kay Thwe Hlaing; Martin Seeliger; Stephan Opitz; Khin Mi Mi Win; Win Thuzar Nyunt; Nilar Aye; Aung Aung; Kyaw Kyaw; Frauke Kraas; Helmut Brückner
• Keywords: Coastal erosion; Geologic record; Storm Surge; Deposition

Abstract The catastrophic storm surge of tropical cyclone Nargis in May 2008 demonstrated Myanmar's exposure to coastal flooding. investigation sediments left by and its predecessors is an important contribution prepare for the impact future cyclones tsunamis region, because they may extend database long‐term hazard assessment beyond relatively short instrumental historical record. This study, first time, presents deposits modern from coast Myanmar. aim establish regional sedimentary characteristics that help identify discriminate geological record, document post‐depositional changes due weathering years after deposition. These findings if used interpret older will existing record flooding events Evaluating can be related specific events, such as 2006 Mala 2004 Indian Ocean tsunami, indicates similar both types sediments. Landward thinning fining trends, littoral sediment sources sharp lower contacts allow differentiation underlying deposits, while discrimination between tsunami origin challenging based on applied methods. analogues also demonstrate a rather low preservation potential sand sheets carbonate dissolution, formation organic top soils, erosion. However, depressions sufficient thickness (>10 cm) preserved where shoreline prograding or stable. In most seaward swale beach‐ridge plain at Rakhine coast, two have been identified addition Mala. Based combination optically stimulated luminescence, radiocarbon 137 Cs dating, younger layer 1982 Gwa, probably result event took place prior 1950. Comparison with records archive only sensitive category 4 (or higher) landfall directly few tens kilometres north study area. While presented are restricted last 100 years, luminescence ages beach ridges indicate swales landward one investigated this might provide information least past 700 years.