Abstract
-
Characterizing sediment provenance from the geologic and geomorphic records left by natural disasters may shed light on the sedimentary and
hydrodynamic processes happening during such events. In this study, we collected modern sediment samples from onshore, offshore, the 2004
Indian Ocean Tsunami and three palaeotsunamis and a 2007 storm deposit from Phra Thong Island, Thailand. To explore the relationship between
the sedimentary deposits, we examined grainsize parameters, mineralogy (from X-Ray Diffraction) and trace element geochemistry (from X-Ray
Fluorescence) from each deposit and applied a series of statistical analyses including cluster analysis, principal component analysis and discriminant
function analysis.
Our results show that the mineral content and grainsize parameters are statistically inadequate to distinguish the provenance of tsunami deposits, but
that trace element geochemistry is potentially a good discriminator. In most of our statistical analyses, the trace elements show that the onshore
samples are distinguished from the offshore and tsunami sediment samples. Also, the near-shore samples and tsunami deposits are very similar. This
reveals that the near-shore marine sediments significantly contributed to the 2004 tsunami deposits. In addition, our analyses show that all four
tsunami units statistically differ from each other, and that the storm deposits are similar to the second palaeo-tsunami group. This indicates that
sediment sources are diverse and that the tsunami deposits did not come from the same source. Such complexity raises questions about the origin of
various sedimentary environments and it also reflects the importance of local context and paleogeography that cannot be ignored in tsunami
provenance studies.