A RE-EVALUATION OF SUBMARINE LANDSLIDE DEPOSITS BENEATH THE MAKASSAR STRAIT AND ITS TSUNAMI POTENCY

• Main Author: Valentra, Rizqi
• Format: Theses
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/70702
• Institution: Institut Teknologi Bandung

In 2020, several Mass Transport Deposits (MTD) were identified beneath the Makassar Strait. These deposits considered as the product of submarine landslide that was not caused by a seismic activity but by rapid sedimentation from Mahakam Delta and slope erosion and deposition by Indonesian Throughflow. Although these deposits had been mapped, the volume of each deposit and the formation process are still questionable so that it is important to re-evaluate the deposits using different point of view and more data. Besides the unknown process, it is also unknown whether these deposits were tsunamigenic or not. This research used re-evaluation result to simulate a landslide induced tsunami using numerical model known as Non-Hydrostatic WAVE Model (NHWAVE) and Fully Nonlinear Boussinesq WAVE Model (FUNWAVE) to observe the impact of these deposits movement on recent conditions. The re-evaluation successfully mapped 17 MTDs with volume ranges from 6.38 km3 to 351.69 km3. These dimensions are much smaller compared to previous research. Based on the re-evaluation, these deposits were formed in such a long process where the movement of the materials were extremely slow with ITF as a preconditioning mechanism that allow these deposits to be very large in dimensions. Although the size of the deposits was extremely large, these deposits were interpreted to be not tsunamigenic. However, along the re-evaluation process, several much smaller depositswith unknown process were found. Also, looking present day ITF interaction with the slope, this area has the potency to have failure in the future. Eight tsunami scenarioswere run to accommodate this possibility and a tsunami class VII-VIII was generated with the maximum height of almost 4 m with arrival around 21 – 40 minutes on Sulawesi and 20 – 111 minutes on Kalimantan. Although tsunami source located closer to Kalimantan, the impact of the tsunami was worst in the Sulawesi shoreline.