HR: 16:35h
AN: T24A-02    [Abstracts]
TI: A Pre-2004 Tsunami Deposit in Thailand
AU: * Jankaew, K
EM: kjankaew@yahoo.co.uk
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Choowong, M
EM: monkeng@hotmail.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Charoentitirat, T
EM: thaicat@hotmail.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Machado, T
EM: terry.machado@gmail.com
AF: Centre for Earth Science Studies, Akkulam, Trivandrum, 695031, India
AU: Martin, M E
EM: memartin@u.washington.edu
AF: Department of Earth and Space Sciences, University of Washington, Box 351310, Seattle, WA 98195, United States
AU: Pailoplee, S
EM: thai_tectonics@yahoo.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Phantuwongraj, S
EM: pu_sumet@hotmail.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Napradit, T
EM: gibb_gibbja@hotmail.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Weerahong, A
EM: ann_wee79@yahoo.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AU: Surakiatchai, P
EM: p-prince@hotmail.com
AF: Department of Geology, Chulalongkorn University, Phayathai Road, Phatumwan, Bangkok, 10330, Thailand
AB: A sand layer from a predecessor to the 2004 Indian Ocean tsunami underlies a freshwater marsh on Phra Thong Island, Phang Nga Province, Thailand. At this marsh, about 300 meters from the sea, the 2004 tsunami left a sand layer about 13 cm thick on top of a peaty soil. The previous tsunami deposit, of similar thickness, rests on another peaty soil about 40 cm below present ground surface. It probably correlates with a pre-2004 tsunami deposit previously reported from Phra Thong Island in a web posting by Shigehiro Fujino. Observed in trenches and cores, the pre-2004 deposit begins with a razor-sharp contact with the underlying soil. The sand itself contains no fewer than 6 layers, all horizontal, defined by differences in particle size (fine sand and very fine sand) and by detrital plant fragments. We also noticed pebble-size clasts of peaty soil. These observations come from the vicinity of UTM coordinates 418975E, 1009496N, zone 47. Many of us participated in previous, unsuccessful attempts to find pre-2004 tsunami deposits in Thailand. We hunted for sand sheets between Phuket to the south and Kho Khao Island to the north, on beach-ridge plains disturbed by tin mining and in mangrove swamps. We also checked pristine, grassy beach-ridge plains of Phra Thong Island, the next island north of Kho Khao. None of these environments offer both a host deposit that contrasts with tsunami-laid sand and a lack of disturbance by tin miners, mud lobsters, and real-estate developers.
DE: 1861 Sedimentation (4863)
DE: 1890 Wetlands (0497)
DE: 4564 Tsunamis and storm surges
DE: 4950 Paleoecology
DE: 7221 Paleoseismology (8036)
SC: Tectonophysics [T]
MN: 2007 Joint Assembly