Detailed measurements of thickness and grain size of a widespread onshore tsunami deposit in Phang‐nga Province,southwestern Thailand |
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| Authors: | Shigehiro Fujino Hajime Naruse Dan Matsumoto Norihiko Sakakura Apichart Suphawajruksakul Thanawat Jarupongsakul |
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| Institution: | 1. Division of Earth and Planetary Sciences, Graduate School of Science, Kyoto University, Sakyo‐ku, Kyoto 606‐8502, Japan (email: shige‐fujino@aist.go.jp);2. Present addresses: Active Fault and Earthquake Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1‐1‐1 Higashi, Tsukuba, Ibaraki 305‐8567, Japan,;3. Department of Earth Sciences, Graduate School of Science, Chiba University, 1‐33 Yayoicho, Inage‐ku, Chiba 263‐8522, Japan,;4. Institute of Geology and Geoinformation, National Institute of Advanced Industrial Science and Technology (AIST), Central 7, 1‐1‐1 Higashi, Tsukuba, Ibaraki 305‐8567, Japan,;5. Dia Consultants Co., Ltd, 1‐7‐4 Iwamoto‐cho, Chiyoda‐ku, Tokyo 101‐0032, Japan,;6. Department of Geology, Faculty of Science, Chulalongkorn University, Pathumwan, Bangkok 10330, Thailand;7. PTT Exploration and Production Public Company Limited, Bangkok, Thailand. |
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| Abstract: | Measurements of thickness and grain size along flow‐parallel transects across onshore deposits of the 2004 Indian Ocean tsunami revealed macroscopic horizontal variations and provided new insights into tsunami sedimentation. The tsunami caused severe erosion of beaches, river mouths, and the shallow seafloor along the coast of southwestern Thailand and supplied sufficient sediment to deposit a kilometer‐wide blanket of sand on the land surface. The tsunami deposits generally fine landward with some fluctuations caused by local entrainment and settlement of sediments. Sediments of medium and fine sand are restricted to a few hundreds of meters inland from their source, whereas finer grained sediments were suspended longer and deposited 1 km or more inland. Although the thickness of the tsunami deposits is strongly influenced by local topography, they generally thin landward. In areas of low‐relief topography, the rate of landward thinning is exponential and reflects the dominance of sediment supply to nearshore areas over that to areas farther inland. |
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| Keywords: | grain size Indian Ocean tsunami Phang‐nga sediment thickness Thailand tsunami deposit |
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