IDENTIFICATION OF TSUNAMI DEPOSIT AT MEULABOH, ACEH (INDONESIA) USING GROUND PENETRATING RADAR (GPR)
Keywords:GPR, Distinguishing, Tsunami Deposit, Post-Tsunami, Pre-Tsunami
Tsunami is a catastrophic event that affects coastlines on a large scale with heavy casualties. Recent tsunami deposits and processes are studied for a better understanding of the disastrous event to enhance hazard assessment of tsunami-prone coastal areas. This research paper explores the 2004 tsunami deposits at Meulaboh (Aceh) to identify the thickness of post- and pre-tsunami deposits to improve risk assessment. The study consists of 4 Ground Penetrating Radar (GPR) survey lines near the Meulaboh shore. Two pit holes were dug along the survey lines and the deposition sequences were recorded. Records of the pit holes show good correlations with the intensity changes of EM waves from the GPR profiles and provide a clear insight into the subsurface tsunami deposit sequences at Meulaboh coastal area. The GPR results show that the 2004 pre-tsunami sediment deposits can be identified with a thickness of 0.3-1.5 m, while post-tsunami 2004 sediment deposits were also identified with a thickness of 0.1-1.2 m. Both sediment deposits known as alluvium were caused by natural coastal processes and erosion with an estimated depositional rate of 0.007-0.09 m/year. The thickness of the 2004 tsunami sediment deposits was identified as 0.2-3 m. This study revealed that the thickness of all the sediment deposits is thicker when approaching the shore, and GPR is a very efficient technique in investigating shallow subsurface with high data resolution to distinguish different deposits with high accuracy.