Multi-proxy approach to identify the origin of high energy coastal deposits from Laem Son National Park, Andaman Sea of Thailand

Understanding the frequency of high energy storm and tsunami events is crucial for apprehending the vulnerability of coastal communities. Identifying and dating sedimentary evidence deposited by such high energy events can assist in the planning and installation of suitable protection measurements. The Andaman Sea coast of Thailand is particularly vulnerable to such events as illustrated by the 2004 Indian Ocean Tsunami. Here, three shore-perpendicular transects and ten sediment cores along a beach ridge in the northern part of Lam Son National Park, Ranong Province, Andaman Sea coast are investigated with respect to high energy deposits. A multiproxy analysis was conducted including stratigraphical correlations between cores, detailed description of physical characteristics, sedimentary structure, grain size, organic matter and carbonate content as well as identification of the remains of marine organisms. Optically stimulated luminescence (OSL) dating was applied for determining the age of the sediments on this beach ridge plain. The stratigraphy and sediment characteristics, in particular composition, of the sands in the study area clearly allow us to distinguish between high energy deposits and normal beach sediments. Two high energy deposits were identified and attributed to result from the 2004 Indian Ocean Tsunami as well as a past storm, which, based on OSL dating occurred more than 340 +/- 20 years ago.

Automated summary

Understanding the occurrence frequency of high energy storms and tsunamis is crucial for assessing the vulnerability of coastal communities. This study investigates sedimentary evidence along the Andaman Sea coast of Thailand to identify and date high energy deposits, which can assist in planning suitable protective measures. A multiproxy analysis, including stratigraphic correlations, physical characteristics, sedimentary structure, grain size, organic matter, carbonate content, and marine organism remains, was conducted. Optically stimulated luminescence (OSL) dating was used to determine the ages of the sediments. The results distinguish high energy deposits from normal beach sediments, with two deposits attributed to the 2004 Indian Ocean Tsunami and a past storm that occurred over 340 years ago according to OSL dating.