Sediments deposited by the 2004 Indian Ocean Tsunami along the Malaysia-Thailand Peninsula

Stratigraphy, grain size distribution and foraminiferal assemblages of pre-tsunami and tsunami sediment from the Indian Ocean Tsunami at five sites along the Malaysia-Thailand Peninsula were analyzed to gain information on tsunami sediment source and deposition style. Between three and five stratigraphic 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 uprush high-energy flow separated the fining upward sequences, with the exception of one site (Sungai Burong), which contained a coarsening upward sequence. All contacts between the pre-tsunami and tsunami sediment were sharp or erosional. Medium and coarse sand dominated all of the tsunami sediment deposits and often contained shell fragments. Foraminiferal assemblages were able to differentiate pre-tsunami sediment from tsunami 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.