STUDY OF TALUTI BAY TSUNAMI DEPOSIT 16TH JUNE 2021, ON COAST MAHU POINT 2, TEHORU DISTRICT,CENTRAL MALUKU REGENCY, MALUKU PROVINCE

• Main Author: Rahma Dini, Putri
• Format: Final Project
• Language: Indonesia
• Subjects: Geologi, hidrologi & meteorologi
• Online Access: https://digilib.itb.ac.id/gdl/view/80464
• Institution: Institut Teknologi Bandung

A tsunami hit the coastal area of Taluti Bay following an earthquake with a magnitude of 6.1 on June 16, 2021. The tsunami waves deposited sediments on the coast of Mahu Hamlet, Tehoru Village, Tehoru District, Central Maluku Regency, Maluku Province. This study aims to determine the physical appearance of tsunami deposits on the coast of Mahu Hamlet (point 2) based on outcrop analysis, megascopic analysis of sediment samples, granulometry analysis, and microfauna analysis to ascertain the origin environment of the deposits. The research involved examining 8 tsunami sediment samples and 4 pre-tsunami beach sand samples from one location. The physical appearance of the tsunami deposits, observed through outcrop analysis and megascopic examination, shows massive characteristics with erosional contact with the pre-tsunami beach sand deposit layer below. These deposits exhibit rip-up clasts, a dark gray color, coarse silt-sand grain size with gravel-sized fragments – crustal in nature, displaying an angular–rounded grain shape and moderate–poor sorting. The composition includes quartz, calcite, phyllite, and schist, with terrestrial materials like plant remains, plastic waste, and glass fragments. In contrast, no terrestrial material was found in the pre-tsunami beach sand deposits. The results of granulometric analysis of tsunami deposits show a bimodal grain size distribution curve, indicating a mixing of fine and coarser sand grain sizes during deposition. In the tsunami deposits on the coast of Mahu Hamlet, at point 2, a mixture of pebble-sized metamorphic rock fragments was also found floating on a finer-sized sand base. Based on the physical aspects of the observed deposits, the tsunami deposits in the study area are considered to have been deposited under the influence of turbulent currents. Microfauna analysis suggests that the environment of origin of the tsunami deposits is the marine environment of the middle neritic-outer neritic zone. The results of the tsunami deposit analysis were compared with those of previous research. The tsunami deposits on the coast of Mahu Hamlet (point 2) exhibit physical characteristics similar to the 2004 Aceh, 2018 Palu, and 2006 Pangandaran tsunami deposits. However, there are also differences, notably in grain size, which is finer with moderate-poor sorting. This discrepancy is indicative of the comparatively lesser size and strength of the tsunami waves that reached the coast of Mahu Hamlet compared to the 2004 Aceh, 2018 Palu, and 2006 Pangandaran tsunami waves.