THE SEDIMENTS DEPOSITED BY THE INDIAN OCEAN TSUNAMI ALAONG THE MALAY-THAI PENINSULA

We analyzed stratigraphy, grain-size distribution and foraminiferal assemblages of pre-tsunami and tsunami-lain sediment from the Indian Ocean Tsunami at five sites along the Malay-Thai peninsula to gain information on tsunami sediment source and deposition style. Between three and five stratigrahic units were identified at each site and contained between one and three fining upward sequences reflecting waning flow or pre-backwash deposition. Coarser sand layers reflecting forewash high-energy flow separated the fining upward sequences, with the exception of Sungai Burong, which contained a coarsening upward sequence. All contacts between the pre-tsunami and tsunami-lain sediment were sharp or erosional. Medium and coarse sand dominated all of the tsunami-lain sediment deposits and often contained shell fragments. Foraminiferal assemblages were able to differentiate pre-tsunami sediment from tsunami-lain sediment where no lithological or grain-size distribution change was evident. Between two and four foraminiferal zones were identified at each of the five sites and provided estimates of sediment source and wave characteristics.