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[P-05] Tsunami Simulation in the 28 September 2018 Palu Bay, Indonesia, Using Submarine Landslide Source and Two-layer Depth-integrated Modeling

*kwanchai pakoksung¹, Anawat Suppasri¹, Fumihiko Imamura¹, Cipta Athanasius², Amalfi Omang², Abdul Muhari³ (1. International Research Institute of Disaster Science (IRIDeS), Tohoku University, 2. Center for Volcanology and Geological Hazard Mitigation, Geological Agency of Indonesia, Bundung, Indonesia, 3. Coastal Disaster Mitigation Division, Ministry of Marine Affairs and Fisheries, Jakarta, Indonesia)

Keywords:Tsunami, Submarine landslide tsunami, Palu tsunami, Two-layer modeling, Numerical simulation

The earthquake at 28 September 2018 (Mw 7.5) of Palu-Koro fault in Sulawesi Island has raised concerns about potential impact of generated tsunami by submarine landslide in Palu Bay, Indonesia. Based on the aforementioned unusual information of this tsunami, this study aims to investigate its possible sources using preliminary available data at early stage. Iterative inversion of global seismic observations guided by forward modeling of regional geodetic and tsunami records produces a self-consistent fault slip to create landslide location. This earthquake is similar to other large event in the area but different in generated tsunami from landslide earthquake. The epicenter is located in the land at depth about 10.4 km and its displacement is about 1 – 8 m in horizontal direction. The horizontal displacement of the Palu-Koro fault generated a landslide tsunami that covers around Palu Bay, showing hazard along the coast area from the wave. Two-layer modeling (soil and water) based on shallow water equation was used to simulate the tsunami propagation in the Bay with severe, moderate, and minor impact. The tsunami height from submarine landslide sources with combination of small and large volumes could reach up to 3.0-7.0 m along the Palu shores. The impact along the coast line of Palu Bay from peak wave can be implication for tsunami hazards for the area in future.