MICROFOSSIL & GRAIN SIZE ANALYSES OF SEDIMENT DEPOSITED BY THE INDIAN OCEAN TSUNAMI ALONG THE WEST COAST OF THE MALAY-THAI PENINSULA

Early on December 26th 2004, 255 km SSE of Banda Aceh, Sumatra, Indonesia, a magnitude 9.3 earthquake occurred. The tsunamis generated from this event caused damage and destruction to countries with coastal communities in the Bay of Bengal and Indian Ocean, including; Indonesia, Thailand, Malaysia, Sri Lanka, and India, and as far afield as the east coast of South Africa.

We recorded the tsunami flow depth, the number and direction of waves, maximum wave run-up, and tsunami deposited sediment characteristics and thickness from a suite of sites running south to north on the Islands of Penang and Langkawi, Malaysia, and Ko Lanta, Ko Phi Phi Islands, and Khao Lak, coastal western Thailand. We analyzed the grain size and foraminiferal content of sediment samples retrieved from short cores or trenches that ran along transects perpendicular to the coast at each site. The short cores contained the tsunami deposited material and underlying pre-tsunami sediments. Analyses provide information on wave dynamics at each site including; sediment load, transport, provenance, and post-tsunami depositional change and how this varies along a south to north trend of increasingly impacted areas. Furthermore, these modern tsunamis deposit characteristics will enable us to garner a better understanding of their paleo-counterparts, which hold information regarding their timing and frequency.