Identification of candidate paleotsunami deposit from sediment layers drilled in Seubadeh located in South Aceh of Indonesia

Abstract

This study is conducted to identify prehistoric tsunami deposit (paleotsunami) in Seubadeh village, located in South Aceh Regency, Aceh province, Indonesia. Regional morphologic and seismic characteristics suggest that Seubadeh village is an area that stores tsunami deposits, both new tsunami deposits and prehistoric tsunami deposits. Therefore, in this study, the search for paleotsunami deposits was carried out in Seubadeh village. The tsunami deposit samples were taken at several points in Seubadeh village using a hand drill with a depth of more than 2 m. Sediment classification of the collected samples using Troels-Smith method shows a candidate layer of paleotsunami tsunami deposit was found between two clay deposits. The layer is dominated by plant roots and shell material. In addition, the sediment samples were sieved using a mesh to evaluate the grain size distribution of clay, silt and sand. The results of the grain size distribution and color evaluation of the respective layer are presented. The results of the analysis of the particle size distribution in the sample and the color of the sample indicate that there are 2 layers that show characteristics as a paleotsunami deposit, namely at a depth of about 170-200 cm and 280-292 cm. The paleotsunami deposit found will be further characterized by an emission spectroscopic technique.