Coastal hazards

Although the majority of the reported tsunamis are from littoral countries of the Pacific Ocean, there are a few cases of tsunamis in the Indian Ocean. Research is currently on, to study the historical records of individual tsunami flood events, which have important implications for disaster frequency, preplanning and coastal vulnerability reduction. Primary data that distinguishes episodes of coastal tsunami flooding within the long-term geological

record on the basis of the microfossil (Foraminifera) assemblage are being assessed. Such analysis assists in the reconstruction of the number of paleotsunami events with specific coastal areas providing a valuable predictive tool for future tsunami recurrence. The hydrodynamics of this type of event contributes to complex deposition. To clearly distinguish storm and tsunami deposits from the under and overlying deposits, a multi proxy analysis is required. A set of palaeecological proxies have been studied in order to establish the full extent of the catastrophic event, but other non-catastrophic changes are also determined. The techniques that are being used include x-ray imaging, sediment visual description, laser granulometry, geochemistry (Atomic Absorption Spectrometry, X-ray Fluorescence), 210Pb, Optical Semi Luminescence and 14C dating, 16O/18O determination, and a range of sedimentological and palaeoecological proxies with the focus of obtaining well-dated tsunami/storm indicators such as salinity changes, grain size changes, erosive and compaction microstructures. Historical data are also used to collect complementary information about the effects of the tsunami and to reinforce the age-depth model of the sedimentary sequences.